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screen printing => Screen Making => Topic started by: Gilligan on May 11, 2012, 04:55:17 PM
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Taken from the Orange Emulsion thread:
We coat outside in the shop, store the coated screens horizontally in the dark room till they dry, then they are put along the wall based on mesh count.
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Interesting. So, (he coats outside) ??? like in a safe light room out in the shop....right? :o
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When emulsion is still "liquid" it isn't really that sensitive.
I don't think his shop has windows but it has large roll up doors... I'm betting it doesn't bother him or the emulsion if those doors are open.
I wouldn't coat in direct sun light (but I wonder if it really would hurt much).
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I coat in the shop with the rollup door open. I don't even have a dark room, I just have screen racks covered in black fabric.
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There are two large windows in the front of our building 5'x 5', one about 3' off the floor which is frosted the second 12' off the floor facing West. My screen closet and coating area is right in front of them. I try to coat in the morning before we start the day so its not to bright.
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I've coated in a dark room for years, and the last few months we have been coating out in the shop under the lights. I've spoken to several guys who know a lot more about this subject than I do and all have said that it is perfectly safe to coat where we do it. Even the Kiwo rep I spoke to said it was fine, especially with the dual cure and diazo emulsions. The way I understand it is when emulsion is in it's most liquid state, it is not light sensitive enough to cause any issues while coating, but once it starts actually drying, it needs to be in a safe light environment. If there was a noticeable difference in being able to hold dots I would have noticed, and I've been very observant with our screens since we've started doing this to make sure that it is ok to do. Even when some gurus told me it was fine to do that, I still tested it before I completely committed to doing it this way.
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When emulsion is still "liquid" it isn't really that sensitive.
I don't think his shop has windows but it has large roll up doors... I'm betting it doesn't bother him or the emulsion if those doors are open.
I wouldn't coat in direct sun light (but I wonder if it really would hurt much).
Sheesh. Ha! You creepy crawlers are just trying to entertain me on a Fri afternoon right? You're joking right? It's "light sensitive". any time in the light takes away from it's strength...and for every second in the light, you are depleting your strength. You do'nt see it in your (one screen) but I bet if you take an emulsion bucket just opened and one that you've had out coating in the light for a week, you would see a major difference in the ability to hold small dots. You'd have to do a new exposure test allover again on the new bucket (because you are currently exposing to what your shop is accustom to) and that is pre exposed- light sensitive emulsion.
Where is that guy that kicks people in the "boy's". I need a job done. Ha!
Ok. I know what you might say. I do great halftones and great screens
. Yes, you probably are very satisfied with your results, since you had to compensate way back when you had "some problem" trying to get everything to jive right. So you adjusted your exposure times or did this or did that, cuz you couldn't figure out what "the" problem was at the time. So you ended up with a band aid and yes, it works great for you now.
Well, here's your problem, or at least one that I can see. Ok. Don't believe me. Oh yeah, you say what? you want me to prove it? ok. I'm gonna prove it. Let me get back to you. ;) Don't believe those flippn' crazy guru's. They aren't authentic guru's.
I was editing whilst Alan was posting. LOL. Alan, I respect ya buddy. I even love your guts and revel in your glory of a great shop that you have. I do believe that you are getting great results. I will say that you are getting those with a band aid effect. Not that it really matters a heck of alot. Pierre was getting great results as it was was too. He use to walk from one side of the shop to the other with a fresh screen to expose it. He swore it didn't affect it much. After some small changes, it showed the difference to the good. I just don't have that specific info as to what that was.
If some "guru" is telling you that it doesn't hurt that much, they either don't really know or are insulting you for assuming that you will not be doing high end work and don't need your exposure times to be as accurate as they can be. Once you adjust, they do burn well. (what does that adjusting cost you tho? Is it $, exposure time? I haven't even checked yet and am confident I'll find the answer. If not, then I'll eat some crow and Alan and G can kick me in the boy's. Figuratively. ;)
Am I being like an arse? I probably am, but really, I'm just loving a challenge that I brought upon myself, initiated by myself. I figure you all are saying, Who gives a patootie, my screens are fine. Well, I wasn't trying to be a smart arse. Just wanting to make double sure. You all "could be right" but it's highly unlikely. ;)
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Thanks Dan. (I love ya)
Same thing happens to emulsion when exposed to light when wet as when you expose a humid screen--the diazo crosslinks with water--making a useless bond--at least with a diazo/dual cure.
Edit: I have very little experience with SBQ emulsion, if there's some reason they are totally different, I'd love to learn the how and why.
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I believe one of the guys that said it was ok to coat in a flourescent lit room was Richard Greaves, but I'll have to try to find that to make certain. One of the other gurus is the technical sales rep for Kiwo so I think he knows a little bit about it and hopefully he isn't insulting me. I think there is a possibility that you are right Dan, and coating where we are might be keeping us from holding 100% of our halftones versus the 98-99% that we are holding now, but just as adamant as you are about this not being a good idea, I'm equally as solid in my opinion that I can't hold one single percent more halftone dots if I coated in a light safe room. Trust me Dan, I'm certainly not thinking you're being an ass, I like this kind of debate and we're all adults here and I think we can debate this without anyone's feelings getting hurt. Something good will come out of this argument as long as we all act like adults like we have thus far.
Not that I don't trust your thoughts Dan, not at all the issue, some of the guys that have said that coating in an average UV light setting is ok are really some of the best and most knowledgeable guys in the industry. I don't know if they'd appreciate me throwing their names out in this debate but I'll contact them to see if they don't mind or perhaps would like to join the discussion.
If by chance not coating in safe light is really not a good idea, I'll probably move things back to the way they were, but honestly, I can't see the work that we are trying to do with 55 lpi halftones is going to be negatively affected by doing things the way we are. Like I said earlier, I have not noticed any issues, but maybe we aren't doing the quality of work here that we would notice. I'd like to think that we are, but it's all subjective. If I have 1000 halftones on a certain stencil, and I'm losing 10 of those during prep, and I can keep those ten by coating in a safe light room, I'm the kind of guy that will move to the safe light room. It might be a lot more significant than that, I'm just throwing out some numbers for shats and gaggles.
It's all good Dan-O, I enjoy this, we will all be better off after this thread is all said and done.
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Ok. I feel ya. I know where you are coming from. I think when I really dissect where I feel it makes a difference worth debating over is in accurate or ( optimum exposure efficiency) resulting in a faster (exposure times). being able to go from 4% dot to a 3% dot may also be possible with a more accurate exposure, but that is just where the results really should have been. I think you would have an additional improved result.
If your Wet emulsion that you opened on Tues. is already exposed by ( lets say 1%), after 2 days of being exposed to light for a few minutes, a couple times a day, then another 2 days its been exposed by ( lets say 3%) and by Monday, you open it up and coat using the last of it and its been exposed at 5%, then that has to play a role on exposure time. Your exposure results will be slightly harder to get an accurate exposure than let's say it could have been with protected emulsion.
This is common sense and I don't think anyone is going to argue that this part would be true. So, the real question is, how much of a difference does it really make? This question is going to have a different answer for each shop. This is not a life threatening choice like smoking, but it's like saying, smoking affects everyone differently. The fact is, its not the best way to handle treating your body. You really shouldn't do it but you can choose to. Exposing your emulsion to light is sort of similar. Here is why.
A shop that opens a lid 1 time a week in daylight for a gallon and takes 4 weeks to use it up will not experience much of a difference. A shop that goes though a 5 gallons a week opening and closing a lid multiple times a day ( in daylight) should be measurably adversely affecting your exposure time. As an example, Your quality results are going to change from the coated screens freshly out of the can to the end of the bucket.
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My biggest problem with not having a dark room is dust. I really can't keep my screens dust free. When I move shops that is the first issue I will address for sure.
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If your Wet emulsion that you opened on Tues. is already exposed by ( lets say 1%), after 2 days of being exposed to light for a few minutes, a couple times a day, then another 2 days its been exposed by ( lets say 3%) and by Monday, you open it up and coat using the last of it and its been exposed at 5%, then that has to play a role on exposure time. Your exposure results will be slightly harder to get an accurate exposure than let's say it could have been with protected emulsion....
Don't take this the wrong way but Dan, you are basing your entire premise based on completely made up numbers.
You don't know there is a 1% exposure when you open the lid. What if the actual exposure is .0000001%? If you base your calculations on that made up number it is completely insignificant for ANY textile work and probably most other uber delicate work.
We need someone with true chemical engineering knowledge of how emulsions work and are effected in different states (liquid in this case) to have real data to work with.
For academic purposes (though it would serve no real practical purpose) I wonder how long it would take for emulsion that is constantly being churned/stirred to crosslink or anything similar to that if in a bucket exposed to the sun.
If you kept it moving then it wouldn't be able to have a surface skin that could "dry up" and crosslink and then you would have a small clue at how much daylight would effect it.
If you wanted to make this a semi-practical test, you could take said bucket and pull some of the emulsion out after an hour of this "churn and burn" and coat a screen and then run an exposure test. Then wait another hour and do the same... blah blah blah rinse and repeat for as long as you like or until it starts to make a measurable difference.
Then maybe with that data you can extrapolate some real numbers at how it effects it. Still WAY too many variables in this test for concrete numbers, but it would be interesting data none the less. If you want a bit more scientific numbers then you could use an exposure unit for your light source and then maybe you could log light units as a reference for "time" exposed.
Simply saying someone will have to increase their exposure time because of moving their coating outside of a light safe area isn't all that accurate. Alan, did you guys have to change anything? They just moved from light safe to non-light safe and if anyone would catch something like that I am certain Alan would. Is he doing lab accurate testing? No, but it's closer than guessing based on gut feelings.
Please take all of this in the same pursuit for the truth as anyone else already in this discussion.
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This turned into a great discussion. We coat under yellow sleeved fluorescents, dry in a commercial drying cabinet, and store in dark cabinets. Set up under the aforementioned yellow, and the washout area has some ambient outdoor light, but mostly yellow. For years we worked in really dark, dim light, but it was overall bad for the eyes, and using the bright yellow lights didn't change our quality. It did the lose the dungeon feel though. My thought on the sensitivity is that if the sensitizer comes in a brown opaque container in a box, it must be sensitive, I don't see why wet or dry would make a difference. If you coated the screens in normal daylight, which is rich in the wavelengths that affect the emulsion, then some pre-exposure has to be happening, which I would liken to laying a neutral density filter on your screen, so that when it's exposed, the very finest detail would be the most affected, as it's already slightly undercut. So, in an example like Pierre's Blue Moon shirt, where the grain size of part of the image is from 280 ppi resolution, then those ultra-tiny bits may or may not come out; some 3" letters in Impact font probably won't exhibit any issues. I vote for safelights.
Steve
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Simply saying someone will have to increase their exposure time because of moving their coating outside of a light safe area isn't all that accurate. Alan, did you guys have to change anything? They just moved from light safe to non-light safe and if anyone would catch something like that I am certain Alan would. Is he doing lab accurate testing? No, but it's closer than guessing based on gut feelings.
At the beginning of opening the bucket of emulsion, his exposure time is still the same as at the end of his opened bucket of emulsion a few days or weeks later. I'm saying that at the end of (any company's 2 weeks of having an open container of emulsion) will have adverse affects on the image stencil. It might not be "noticeable to Alan or Joe or Tom, but it's noticeable to some company over time.
If Alan does the type of work that most average shops do (basic spot color prints), for the biggest part of his business, nobody would think of changing exposure times once switching from a dark room to out in the light. The affect is not dramatic or instant, it's over time. It's like saying, I looked straight into the sun and nothing happened so those people who say "Don't look into the light because the UV rays are bad for your eyes".
Lets face it. We are all human. Even a Super seasoned coater might miss this. The thing is, he's happy with his exposure times right? So "the way he's doing it now, (the results he gets) he's ok with. Even tho, the results may be inconsistent from beginning to end of open emulsion. One doing this might even say, "coating screens in daylight does not affect my exposure times".
When I say "inconsistent", it may never be really noticed because of the randomness of screens and art on those screens coming in every day. One day of coating (with the bottom of a 5 gallon bucket of an old emulsion that has been opened out in the light, he might coat 7-110's, 2-86's, 10-230's & 4-305's In that mix of 305's, he might only have 1 (one) 305 mesh that had 6% dots in the art. Once exposed, it might not come out all the way. It might be a little saw toothed. Why? Does your screen room guy even notice? If he does notice, does he mention anything? Would you normally tell him to toss that one out and burn another screen because the 6% dots did not come out or would you just use it? Many shops would use it on a normal basis so it goes unnoticed.
You might have at one time called on Kiwo tech support and you say, I am out of room in my dark room, can I coat my screens out in the shop in day light, will this affect my emulsions? Your "guru" might say, "Ahe, it's not a problem for you." because maybe he knows your 1% of your screens in a day that require holding 4% in a 55 line screen. Does it affect your exposure over a long perod of time? Yes, Is it significant enough for you to make a change? That is up to you and the amount of work and level you want to maintain as your standard.
So, with all the stencils burned that day (with that old pre-exposed emulsion), you got 1 (one) mesh that missed holding a few lower dots. Nobody lost a limb or life over it and more than likely nobody said "Well, shoulda not used that bottom of the pre-exposed emulsion". Nobody in the every day process would notice or care that this was the source. All the while you are thinking pre-exposed emulsion it does not matter).
For this type of detail, maybe it doesn't matter for your shop. Maybe that is the norm and nobody is the wiser. Maybe this is why one can say "I never changed a thing and just started coating outside in the light. NO difference.
Where does this affect us?
1st, maybe in how we provide separations. Maybe you tell your sep artist that you know you can only hold down to 6% dots so change everything to show 7%. (so that had changed).
2ndly, Your exposure times are consistent....but are not at optimum for all screens (for your varying strengths of emulsions).
Taking this to even more extreme example, imagine a shop that only did low mesh, big and bold type like athletic printing. This would not matter to them at all. They could hold all it and never flinch as you can often get away with over exposed BIG BOLD TYPE.
Imagine a shop that did nothing but process and sim process and are known for this. They specialize in this area. 230's, 305's and 350 mesh. Would the pre-exposed differences between a fresh can and an old can make a difference? I think it would.
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For debates sake, the delineation between fluorescent lit room and sunlit room needs to be made--the sunlight will expose any emulsion unusually quickly--overhead fluorescent lights will not.
If Alan is talking about coating in a shop lit with fluorescent lights, I can't see much of a change happening between that and a 'light safe' environment.
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@ Gilligan
G, all I said was " lest say". As in (we don't have any real numbers, so let's just make one up for the discussion).
Let's use your numbers and "let's say" 0.00001
Again, I could be wrong, but I doubt it. The point is, light affects the emulsion. Could be by .0000001 or could be by 1% over a couple days and 3% over...xxx fill in your favorite number for now. You are correct tho. I probably will never actually get accurate numbers from a scientist. I just know it will affect the print at some point.
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We coat all of our screens in open light, no dark room here.
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Dan, the only thing I will say is until we have actual numbers in front of us this whole discussion is rather futile and barely academic, certainly not practical. We certainly shouldn't even hint at "absolutes".
Does it affect your exposure over a long perod of time? Yes, Is it significant enough for you to make a change? That is up to you and the amount of work and level you want to maintain as your standard.
Is it enough to make a change? We don't know. It may not mean a SINGLE dot difference and all this concern might be for nothing. Then again it might make a more significant difference then even you are speculating it might.
The thing is we have no clue at this moment and until there is data the discussion should keep a VERY hypothetical nature.
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You are saying I don't have hard fact proven #'s so don't discuss it? Pfft.
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Not at all Dan, I just said to make sure that we stick to purely HYPOTHETICAL language.
A lot of the way you are saying things are speaking like there ARE hard fast numbers. Sure you preface it with "if" at the beginning... but the post goes on for like 6 paragraphs and any "ifs" you tossed out there kind a little lost in the discussion.
Maybe I'm just a stickler for facts and proper representation of them.
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Maybe im just passionate about it. Lol. But don't bust my balloon man.
Everyone will each take away what they will interpret from my post. Im om with how you feel about it. Call it hocus pocus or a pipe dream I don't mind. I can't help what one person see's as offensive or accurate or inaccurate. It's inaccurate to say light does not affect the outcome at at all. Nobody really said that. It's been said that it doesn't affect it "much". So pretty much, we all have an understanding that ( it does) to some degree. I'm saying that depending on how long it's exposed, it can affect your stencil and in some cases, to a measurable degree. The actual numbers or % of pre- exposure do not matter to me in this discussion. We aren't that far yet to give precise amounts. If you want to spend 3-500.00 on tracing a 5 gallon bucket, please let us know how it turns out cuz I ain't gonna test it. I'll take whatever word Kiwo has to say and only take 90% of that as all truth also. Sometimes a supplier doesn't know everything for sure so they just spit out stuff. I would consider Richard Greaves a real honest to goodness authentic guru and don't believe he will say that light does not affect the outcome of emulsion.
Call it .000001 or call it a nano second. Either way, over time you are decreasing your quality. Again, is it noticeable in all cases? Now, is it noticeable at all in any case? I say yes, we will have situations in our normal process were this will be measurable. Some of those shops like a Mirror Image or a Andy Anderson should be able to see these differences. My real stance, is that if it can cause a problem at any point, why do it?
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I guess it is like a 5 point restraint harness in your car... it would definitely be better to have one but you aren't going out and spending the money to put one in your car nor do you really want to strap into such a thing every time you jot off to the grocery store for milk. But if/when you get in a wreck (this is more likely to happen and more important than a "not so perfect" t-shirt) a 5 part harness will be a HUGE thing if you had it. Also do you buy your vehicles based on how many air bags or if they are at the TOP of the safety rating?
Do you always handle fragile items with the care that you should? Probably not because "chances are, nothing will happen".
So does all this increase the chance of something happening? Of course it does, so why chance it? Convenience, time, money... a multitude of things cause us to not operate at 100% the level we should or take EVERY precaution we should. Almost every minute of every day we make these sorts of compromises with ourselves.
This is just the world we live in... it's far from perfect.
I would like to know what is more of a factor in these "differences"... the ambient light in which you coat in or your imperfections in coating technique (we are human), or inconsistencies from one buck of emulsion to another, or drying time/humidity of the emulsion when exposing, temperature of the water when washing out... There are just SO many variables that are almost impossible to control I would say it would be EXTREMELY hard to test this in the real world.
BUT, that being said... I absolutely WANT to know the answer to this and I would possibly make adjustments to how/where I coat.
Also, for the record I coat under fluorescents and don't have much outside light coming in (just around the cracks of the doors). I even block out as much of that light with black bags when I'm moving screens around and registering them for exposure. I do this even though I watch my buddy and his employees not take hardly ANY precautions... hell, they coat 1:1, dry on their sides and only use a curtain (not even black) to cover their screens (from coating till exposing). Not ideal at all... BUT they are one of the bigger shops around this area.
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All good points. Nobody can take anything you say lightly.
One thing I'd say is do not ever bank on a large shop being efficient or profitable. They are some of the worst. They have the money and resources for all the gadget yet fail at using then when sitting next to them.
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All good points. Nobody can take anything you say lightly....
I thought we were supposed to be all acting like adults so this discussion could stay educational.
So much for that... I'll step out now since I really don't have any real world experience to bring to the table anyway.
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Don't know what your upset over. ??? Unless I am miss understanding something, my statement you quoted is a compliment. I guess I have to go research what " nobody can take what you say lightly" means in other states.
It was meant to say, you say some serious hard core stuff and have many valid points behind what you say. "nobody can take what you say lightly". I think that was pretty clear.
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I highly doubt coating under shop lights or in a darkroom hardly matters, it works both ways for many people. Big deal lol... can't we all just get along without getting into a nerdy debate?
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I'm all about Nerdy. It's what I do, who I am. Don't fight who you are. :) I'm not Tech Nerdy, just annoyingly nerdy I guess.
We all really are getting along well. It's just that G apparently miss understood my intentions and it sort torqued him the wrong way. Crap happens. We will live.
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I do believe Dan is correct, the light in the shop will affect the emulision. How do you grt rid of the last little bit of emulsion. You take the lid off set it in the sun and peal the cured stuff out.
Coating in the ambiant light works for us. Not every shop is the same. Most of our jobs are 1-4 color maybe some half tones or fine detail. We do 4 color and simulated on occasion and they all have turned out fine. Dan did some seps for us about a month ago. We didnt get the job but hope to try it over the summer. It is some cool artwork.
I think the question is what percentage of shops do such detailed work that the ambiant light effects the quality of the finished product.
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My apologies Dan... we have had some heated discussions in the past and I took you the wrong way.
Sorry about that.
Yes, I too enjoy nerdy... this is one reason why I'm glad Alan is as close as he is... he seems to dig all the ins and outs and behind the scenes that I like to know about.
I'm also passionate about facts and truth and making sure things are clear and not misleading... basically I hate spin and I fight it when sometimes it doesn't need to be fought, sorry if that is what happened here.
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I do believe Dan is correct, the light in the shop will affect the emulision. How do you grt rid of the last little bit of emulsion. You take the lid off set it in the sun and peal the cured stuff out.
Truly a question out of ignorance here (I'm still on my first gallon of emulsion... hence why I'm probably not qualified to really take part in this discussion). I just dig the science.
Anyway, wouldn't that last bit of emulsion work the same way if you just left it open in a dark room where it could dry out? Isn't the leaving it open in the sun also a way to dry it out quickly as well?
I could be completely wrong as I said, it is truly a question of ignorance.
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Why would anyone leave the lid off the bucket while coating anyhow? Once the coater is filled I put the lid back on. Also who coats in the sun?
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I think for the most part we are talking about people that coat with spill in sun light from a window or an open bay door.
The argument Dan is making (if I have this right) is that even cracking it open and filling up your scoop coater in said ambient light is bad for the emulsion.
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G, no blood loss, no foul. :). I don't wen remember us ever having any heated discussions in the past. I'm like that. I literally don't hold on to that stuff to long. Heck, Frog was made at me for a few years I guess. Never knew it. He had to tell me three or four times before I'd stop asking him. " what's was it you were made over" then that'd piss him off to just have to tell me again. It was something hatless to me but apparently stuck a cord with him. He loves me now. ;)
Anyhow, I replied to say something intelligent yet forgot what it was.
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Yes,
The argument Dan is making (if I have this right) is that even cracking it open and filling up your scoop coater in said ambient light is bad for the emulsion.
As the emulsion gets older, it gets gummier and is not the best to use for high def work. Thicker and harder to get a nice smooth coat. If I were coating for sim process, I'd switch to a fresh bucket. You can use the other older mud on your 110's
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Take this as you see fit but back when I worked for a major supplier to out industry and the graphic industry I worked with vast amounts of emulsion in,flourescent lit work rooms. We split larger quantities down to smaller quantities daily, we dealt directly with all major emulsion manus and not one of them had a bad thing to say about it at all and from what I understood they even manufactured quite a bit of their product in,direct light. I am sure the manus know exactly what is considered safe and not safe even right down to the slightest in,easy table amount of accidental exposing. We can,all talk about small dots and the possible loss of them if coating in an open light room but what if that is not the case? How do we know with out the manus them selves coming here and telling us? I know for a fact we handled liquid emulsions in direct light with never an issue, we here print textiles but we sold emulsion to companies that used mesh as high as 700tpi that printed extreme detail way above any thing we do. As for cap film that is always handled with care in a safe light room.
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Wouldn't opening and closing the darkroom door have an even more detrimental effect on dry screens than it would on wet screens? Seems logical.
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I do believe Dan is correct, the light in the shop will affect the emulision. How do you grt rid of the last little bit of emulsion. You take the lid off set it in the sun and peal the cured stuff out.
Truly a question out of ignorance here (I'm still on my first gallon of emulsion... hence why I'm probably not qualified to really take part in this discussion). I just dig the science.
Anyway, wouldn't that last bit of emulsion work the same way if you just left it open in a dark room where it could dry out? Isn't the leaving it open in the sun also a way to dry it out quickly as well?
I could be completely wrong as I said, it is truly a question of ignorance.
Some emulsions have a shelf life after mixed so we dry the last bit out before tossing if we hadn't used the whole bucket. You could also say I'm cheap and want the bucket.
I keep the last bit out of the bucket to coat the screens instead of tapeing sometimes, mostly on screens we keep for repeat jobs or our number system.
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I doubt that anyone on this list has the capability to test this. There are too many variable to absolutely control to get superior test results. Probably even emulsion companies might have a tough time testing this. When was the emulsion manufactured exactly? Do you have a finely tuned machine coating that can control the emulsion thickness? Are you going to test it on all mesh counts? Test it on all thicknesses of how you might coat a screen? Is five minutes of light negligible? How about an hour? Two?
We all use an extremely crude process call screenprinting, which means we have to push it to its limits to get outstanding results. Screenprinting has so many variables, some of which are very hard to control or you can't control them. So it becomes even more important that you control the parts of the process that you can. You can do screenprinting effectively with a variety of people coating screens, in hot and humid conditions, with a variety of manufacturers emulsions, with different types of exposure units, with a variety of ways of making your films, .... However, go ahead and use the worst of any of these situations and you will have trouble even printing Whatsamatta U on the front of the shirt. Good screenprinting is all about controlling or eliminating variables.
For best results you want to control all these aspects and buy from manufacturers that sell good consistent products (consistency actually more important than good), have the same person at least coat if not using a machine coater, climate control as best you can... etc. Can you quote your screens in low light? Sure. You probably could do it sometimes in direct sunlight. Would I recommend it? Of course not. Light exposes emulsion. So does heat for that matter. These are two variable that are not that difficult to control, so why would you not control them? Shops that have superior results have safelights in the screen room and try not to keep coasted screens around for to long because heat will also pre-expose them.
I have been in shops that coat in lit areas and they are doing screenprinting in those shops, so I'm sure you can do it. And if suppliers say it is ok, then maybe it is but in my years of doing this I have grown wary of suppliers advice. When pressed you find out that they often don't know why they advise as they do. All shops are not the same and so you can't always know the effect that something will have on one shop over another.
I would recommend safelights. They aren't that expensive and therefore would be one of the first things I would do in a new shop.
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Well said Rick.
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Rick you are correct we should control the variables that we can actually control but to what extent? At the end of the day we all here are t shirt printers should we strive to print dots smaller than the weaves of the t shirt it self? Should we st,rive to control variables to the point it's more expensive than to be practical? I am certainly not saying we should throw all our controllable situations to the curb and all become gutter printers I just feel in a process talked about here for textile printers coating in an open flours room it is acceptable.
I think this could be tested crudely but enough for textile printing purposes. A person can with a high tpi mesh screen coat one in a safe light room and then in a open light room then expose extremely low percentage tints and then examine with a loup. It would not be perfect but surely enought for textile printers. If there is a noticeably difference in the exposure I will gladly accept the theory that it is not safe to coat in open room if striving to print super high end sim process work.
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You would have to coat a handful of screens in both conditions to at least achieve an "average" to make sure it wasn't one of the other hundred variables that could cause a difference.
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Testing a new bucket coated/used in a dark room, tested against a new bucket out in the shop will not be an accurate test. You would need to compare old buckets. (last coatet) of a bucket in each location. I'll also add that a 1 gallon is not going to show (as much) results as having a 5 gallon. Each case (shop) and your amount of times leaving it exposed to regular light is going to make that difference.
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I would suggest its likely it could affect it, just not so likely at the amount of time/light that are in some of these shops. My shop is not super bright. We coat right out in the open, lights on. Never noticed a issue vs when we use to shut all lights off and coat that way.
What I did notice, is that we could see what we were doing better. LOL
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I would suggest its likely it could affect it, just not so likely at the amount of time/light that are in some of these shops. My shop is not super bright. We coat right out in the open, lights on. Never noticed a issue vs when we use to shut all lights off and coat that way.
What I did notice, is that we could see what we were doing better. LOL
Where do you store your screens?
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I'm still of the persuasion that open windows could affect this much more than fluorescents, as well as the real damage being done to the coated screens--not the bucket of emulsion. IMHO, Inkman makes a great point--cap film you're extremely careful with, because it's already a thin sheet with loads of surface area, whereas a coater full of emulsion, or a bucket, only has a very small amount of surface area vs. mass.
RIck makes a great point as well, considering how easy it is to make sure you don't have to worry, why take the chance?
And again, although I have no hard and fast evidence on exactly what would happen--From what I know, a weaker stencil is guaranteed with more exposure to light. How much weaker is the real question.
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I am going to do a test for myself next week. We are currently coating one gallon of emulsion a week, tomorrow I have to crack a new bucket. Currently I have four 260 screens coated in our safe room, starting tomorrow I am going to coat in the open shop when I get near the end of the bucket I am going to coat some more 260's. We have several jobs coming up that require the 260's I will both burn one from the dark room and one from the open light using both the macdermid calculator and my own calibration bar right down to 99% dots. I can then examine the dots under a loup and relay my results here.
This will be done with a bucket that has been opened several times in the open shop light through out the week. I will also make sure to burn both screens when the map is cool. I will also be sure to develope them together at the same time to control the variables as best as possible. This should work.
Another thing never ever mentioned for some reason when it concerns holding dots is how the screen is developed. I have seen people either go to aggressive with the water or not enough this is an area that is extremely important to the finished screen. Let's all remember by eye it is nearly impossible to see those tiny dots during developing so it's very easy to think your are done yet another 30 seconds might open up the final dots.
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I would suggest its likely it could affect it, just not so likely at the amount of time/light that are in some of these shops. My shop is not super bright. We coat right out in the open, lights on. Never noticed a issue vs when we use to shut all lights off and coat that way.
What I did notice, is that we could see what we were doing better. LOL
Where do you store your screens?
We have a 10 and 24 screen drying/storage cabinets from Vastex. Spendy but really helps when we need to go through a bunch of screens at once.
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Wait, heat exposes screens?
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Wait, heat exposes screens?
Yep, that's why one has to monitor a a DIY cabinet that employs a heater or dehumidifier. (It's also an added problem, for inefficient, heat-producing quartz halogen exposure units that are not well ventilated.
100 is about tops for a lot of emulsions, at least the photopolymers that I use. Mirakami says 105, and the new Orange from Ulano that seems to be the buzz in another thread says 104, which is an even 40 in centigrade.
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Wait, heat exposes screens?
Over a certain degree and by whom the emulsion was made, the temperature will activate the cross linking of the emulsion's chemicals.
Do a search about heat vs dehumidifier for drying screens for more about this.
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I think we all agree that eliminating as many variables as we can is the way to go, but my reasoning behind us doing it in the first place was to help train a new employee. She couldn't see what she was doing and I couldn't see what she was doing wrong. Now that I don't need us to coat outside anymore, I need to weigh the pros and cons of doing it and whether or not it can or will affect us negatively. I'm not 100% certain of either way but I'm more sure that coating under regular lighting is harmless. I think either way of coating is going to give the same results so we will be doing it based on personal preference until someone convinces me that it's bad to coat under non uv safe conditions. Now that are dark room is no longer dark, it won't be such a pain in the arse to coat in there any longer. I will keep a close eye on our exposures although I completely agree that we (our shop) don't have the tools, ability or knowledge to properly test this the way it needs to be.
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Yes, The argument Dan is making (if I have this right) is that even cracking it open and filling up your scoop coater in said ambient light is bad for the emulsion.
As the emulsion gets older, it gets gummier and is not the best to use for high def work. Thicker and harder to get a nice smooth coat. If I were coating for sim process, I'd switch to a fresh bucket. You can use the other older mud on your 110's
I never experienced emulsion getting really gummier unless it has not been stored at the right temperature or do you mean by older a time span of over 6 month?
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Exactly eliminate as many variables as you can but it's possible to be spinning your wheels putting too much energy into something with minimal ROI.
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We have been coating in indirect daylight for over 12 years and never had an issue. Mind you we are using Sericol Dirasol 916/917 which is as slow as a snail. Once we had some Ulano QTX and that does not really work with coating in daylight. Saying that I think the really issues arise with the QTX once the emulsion is dry and you handle that screen outside a safe light environment. Same for the cabinet the screens are kept in. Repeatedly opening the cabinet in indirect daylight will pre expose the emulsion on the screens kept inside that drying cabinet.
But if you are worried about indirect daylight from the windows in your workspace why not use clear window vinyl that is especially designed to cut out 99% of the UV light. That way you can have the benefits of daylight in your space without having to worry about the UV light doing damage to your screens.
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we move QTX around all the time with no issues. Open light from dry box to storage, in & out of storage many times, transport to washout room walking directly by a south facing window just don't seem to have a problem?
Most like it is the NY sunshine ::)
mooseman
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Great printing results is like great art. Each persons opinion on what is great is different. None are wrong.
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As much as we all would not agree what is great art, we all know bad printing when we see it. We each might draw the line somewhere differently, but bad printing exists.
Bad printing never seems to be the result of one problem, but a myriad of problems that add up to crap.
In regard to this current thread - safelight covers cost a little over $10. Even if you had 10 bulbs in your screen room to cover that's $120. How much does one job with halftones that you wrestle with for three hours cost you and do you want to take the chance that you are not getting the best halftone dots you could have? It isn't even that you get the best halftone dots you can, more important in the long run is that you get the same halftone dots every time.
Someone earlier mentioned that all the manufacturers said that coating in a lit room was ok. You can't trust information like that necessarily. We had an exposure unit that was inexplicably to me white inside. The manufacturer assured us that if it was black instead of white inside it would not make a difference. All the units I saw in anyone else's shops were also white. We painted ours black inside and it made a huge difference in resolution because of less light scatter I presume.
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I coat in a safe light environment since we have skylights. Don't really want to mess with that variable. Some days it's not bad, but others you get a lot of light through those.
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We coat our screens in a light safe environment as well. We do everything possible to get that last elusive dot consistently. The other major reason we coat inside the screen room is dust. Why coat your screens in a dusty lint filled environment? Every single shop is a dust haven and even though you dont see it, its still there floating around just waiting to stick to your wet screen.
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Not everyone can afford the dark room. Some people just don't have the room.
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I think the bottom line of this discussion/debate is establishing a benchmark of the ideal conditions to coat, expose, and store screens. Those printers, who probably make up the majority of the industry in sheer numbers, can probably cut a lot of corners and never notice a difference on their non-demanding work.
Hell, there is even a segment that starts with hand-held screens, and curing with a heat gun, and exposing screens in the sun. Perhaps a big step for them is a home built press, and a flash panel.
To them, a $3000 investment in a used commercial quality press and belt dryer seems like a crazy pipe dream. With luck, that changes.
It's a matter of how close to the "state of the art" they wish to advance, and frankly, whether the investment will pay off in both better, more consistent results, as well as financial gain. Not everyone's market requires the sophistication of our top shops, so other factors may have more wiggle room as well.
In the end, hopefully, we all do what we can do with what we have, but keep growing.
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Not everyone can afford the dark room. Some people just don't have the room.
I totally understand that. I started in the garage and used our second bathroom as my screen room at night while everyone is sleeping. I know tight space. There is always a way to get the job done. I coated screens after dark and woke up early to put them in garbage bags. The point is that if you have the room use it. if you dont have the room then accommodate the best you can. No matter how small a shop you have you can make the right environment some how.
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Not everyone can afford the dark room. Some people just don't have the room.
I think you make of it what you will. I'm sure some places are maxed out on room in a shop.
For me, I am currently gathering the remaining necessities (screen cleaning/reclaim, etc. ) for the shop in my garage. My dark room (where I will coat screens) will be 4' wide by 9'. Like a long closet.
I want to thank everyone for the great communication and informative posting on this subject. I don't think most thought it would be a controversial topic worth so much effort to discuss. Some still don't think so, but it was a good thread none the less. I am anxious to see Inkmans results but at the same time, his results would only be a contribution to what needs to be a group of results.
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Dan there is a reason I hesitate to even bother with a test like I spelled out and that is no matter the results there will still be nay sayers no matter the results. Yet i feel what I am going to do is more than sufficient to prove or disprove this whole discussion. It is exactly as you laid out Dan going through a whole bucket of emulsion in an open light area through the course of a week. At the end i will expose and develope all range of dots and the calculator, if I see no difference between the 260 coated in our dark room versus the one coated in the open light room I will consider the myth debunked.
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Hell, technically the "UV safe" bulbs in your dark room aren't 100%. Do the ol' coin on a screen trick and see for yourself.
So now, you need to coat and preregister in complete blackness to keep your emulsion 100% effective. ;)
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Dan there is a reason I hesitate to even bother with a test like I spelled out and that is no matter the results there will still be nay sayers no matter the results.
I think we all feel/see this coming. Simply because it's still left open for variables and only one shops results.
I feel if proven to have a 1 or 3% dot loss, some will still not change a thing. Some because of the effort and some for the lack of feeling a need to add another 3% dot. Many do not achieve holding a 5% dot let alone 3 so it won't matter to them. Some do'nt burn halftones higher 50lpi and less than 5% dots so it won't matter to them.
I think tho, we will have many, many more happier people if it's proven that regular shop lighting does not affect the results at all or "enough to gain or lose a few dots. If this is true, then I will also be coating out in my regular light just for the room. ;)
None the less, your results will be a great contribution for you especially. Your one result should not be considered hard factual evidence but considered one sample specimen. It might be conclusive evidence (for your parameters) but not for everyone (in general or as an average).
We should ask for a group of at least 3 or more players. That should not be hard (since we have far more people in here that do coat out in the light).
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Hell, technically the "UV safe" bulbs in your dark room aren't 100%. Do the ol' coin on a screen trick and see for yourself.
So now, you need to coat and preregister in complete blackness to keep your emulsion 100% effective. ;)
I can tell you that my bulb is 99.99999& uv blocked. The light in our screen room stays on for 12-14 hours a day. I just used a 305 last week for a job that has been sitting in there fo 6+ months and it exposed just fine.
You might want to get a different light source if you are having that problem.
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Honest question, was the screen out in the light that whole time?
The test that I've seen conducted is to leave a coated screen out on a table (completely exposed) with a coin(s) taped on the screen. Then after X days wash it out and see if the coin spot washes out differently than the rest.
You can take this further and put multiple coins and remove one a day blah blah blah to see the time frame that it took.
If you screens are/were in a cabinet or stacked or anything that would "shade" them, that could be a difference. Plus, you didn't have the coin on there and getting it to expose fine is relative as Dan has been pointing out. ;)
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Amberlyth and rubylyth loses its filter properties over a period of time, we used to own a UV meter that told us the exact UV being emitted in to the room. Even with brand spanking new amberlyth UV is present none the less it is so freaking neglible for our process it is safe, if working with camera film and developing UV even a negligible amount is an issue.
Dan I am trying to show or prove no loss of dots versus you keep talking about gaining x amount of dots thats not what i am doing, my point is to show in a working day to day shop the out side shop lights will or will not effect enough whether you are in a dark room or not. Simple as that.
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Dan I am trying to show or prove no loss of dots versus you keep talking about gaining x amount of dots thats not what i am doing, my point is to show in a working day to day shop the out side shop lights will or will not effect enough whether you are in a dark room or not. Simple as that.
I think we are talking about the same thing in a different way apparently. As I see your desired results as being the same.
Lets say (since I don't have any hard numbers of what you achieve on a normal every day basis). Lets say you can normally achieve a 60lpi halftone and go down as far as 6% with no issues. 5% usually causes saw toothing er something (in the screen coating room with protected lighting). Now, with this test, your normal procedure (should not change).
If you then coat out in the shop under regular flo or whatever lights above (window or no windows). Over a weeks time of coating screens under regular lights, (the halftone screens coated from the emulsion at the last day of the week) should show an adverse affect (to some degree) and I am saying that degree might be losing 1-2% dots (using the same exposure times) as you normally do in both cases. Will this be an accurate test? Should be, to some degree.
I think that 1 gallon is not going to show as much as it would, had you used a 5 gallon bucket and did the test over 5 weeks. For example, on a 1 gallon, you might only see a 1% change (and that is not really worth celebrating a win or loss over). On a 5 gallon over 5 weeks, you might see a strong measurable difference such as a 4% difference (lets say).
An easy way that someone might compensate for this (for anyone) is to say, gee, my 5% dots are not coming out great. Maybe my exposure times are off? So, maybe you do an exposure test (using the pre-exposed screens) and the results show that you are over exposing your screens a tad. So you cut back on exposure times just enough to hold more dots. Now, as a result of that, your stencil might be slightly under exposed and may not hold up (as well) as it truly could have with an accurate exposure. So when you get that long run of 3-5000 shirts and the screen starts to break down at 1500, you might ask yourself, why? This might be why.
For this reason above, I am thinking that not only might you add 1 or 3 more dots, but you might also strengthen your stencils more for longer production runs, resulting in less interruptions of production flo due to screen breakdown. Just a guess, but makes sense.
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I'll do the testing as well, I have a piece of film that has all kinds of levels of halftones, 1-100%, 20lpi-85lpi, etc. I'll just use that film to test this on some high mesh counts, maybe 280, or perhaps a 330 S thread would be better for this test. I have 2 of those that we rarely use so that's probably the way I'll go.
If I'm getting 98.3% of my halftones to stay, and coating in safe light will move that figure up to 99.7%, then I'll change. If it increases it by a few tenths, probably not worth it, even though it's not that much harder to do. I won't be counting these halftones and the results will be looked at through an 80X lighted loupe so the results will be by the good old human eye (with a little help).
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I have a piece of film that has all kinds of levels of halftones, 1-100%, 20lpi-85lpi, etc.
Great! I have what amounts to the same test sheet that I send to people to determine what the are really holding. I have them burn it on a 230 or a 305 and look around the 50-60 lpi section. Some are very surprised. Many aren't holding the 8-10% range. One was losing under 14%.
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I am actually pleasently surprised at the percentage I can now hold since we got the MSP. I know i am hitting 5% easily probably lower if i take the time to examine. But the macdermid calculator has 10% 50% and 90% at 65 DPI and i nailed them perfectly on a 260 that to me is a good sign
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I have a piece of film that has all kinds of levels of halftones, 1-100%, 20lpi-85lpi, etc.
Great! I have what amounts to the same test sheet that I send to people to determine what the are really holding. I have them burn it on a 230 or a 305 and look around the 50-60 lpi section. Some are very surprised. Many aren't holding the 8-10% range. One was losing under 14%.
Hey Dan, I would be interested in that test sheet. I wonder what I could accomplish with 240 watts of UV tubes.
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... the results will be looked at through an 80X lighted loupe so the results will be by the good old human eye (with a little help).
Geeze, I can't imagine what that would look like. I have a 10x and 15x loupe here that I picked up for dirt cheap mostly as a toy after seeing you guys talk about them so much. I was blown away by the difference and how amazingly close the 15x gets... so if a 50% increase did that I can't even imagine what a 500% increase on that would be! I mean I was looking at 4 color process "dots" on the Anvil swatch book and was amazed that it got that close, with 80x what are you seeing the fibers of the paper?! LOL
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Hell, technically the "UV safe" bulbs in your dark room aren't 100%. Do the ol' coin on a screen trick and see for yourself.
So now, you need to coat and preregister in complete blackness to keep your emulsion 100% effective. ;)
Basically LOL
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Hell, technically the "UV safe" bulbs in your dark room aren't 100%. Do the ol' coin on a screen trick and see for yourself.
So now, you need to coat and preregister in complete blackness to keep your emulsion 100% effective. ;)
I can tell you that my bulb is 99.99999& uv blocked. The light in our screen room stays on for 12-14 hours a day. I just used a 305 last week for a job that has been sitting in there fo 6+ months and it exposed just fine.
You might want to get a different light source if you are having that problem.
Sarcasm detector my be broken. LOL.
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I'm not understanding something. No dark room? Do you mean no screen room? We don't have that many lights in our screen room and we can see fine, I'm not understanding the person that says they can't train someone properly in their screen room. We are not talking about a traditional dark room, I mean a screen room that has fluorescent bulbs with yellow safelight covers.
While I'm at it, let me mention that you need air flow to get rid of moisture in your dark room. I can't tell you how many screen rooms I have been in that have exhaust fans and no way for air to get in the room. Air cannot go out of the room unless air comes in. If you are worried about dust, then put cheap (under $2 usually) furnace filters where air comes in the room or else put the filter on either side of the fans you have for air flow that dries your coated screens.
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No screen room or dark room and the dust is killing me at times. I can't wait to have enough room for a screen room.
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Very good call--I'd say the furnace filter trick is a good idea by the presses too--although very important around pre-press.
No screen room or dark room and the dust is killing me at times. I can't wait to have enough room for a screen room.
Gerry--you can buy four box fans and a four pack of 20x20 cheapo filters for less than fifty bucks. You'll get and ROI in no time on kleenex, and shop cleaning. Not to mention what that ilnt will do to stuff besides your screens. Put one by each presses load station--you'll be amazed at how much crap ends up on the filters--instead of in and on you and your equipment.
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That's probably something I will implement until I can get out of here. Should help with boogers on my screens right where I don't need them.
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No screen room or dark room and the dust is killing me at times. I can't wait to have enough room for a screen room.
Gerry look at the setup Brandt has. One of those cabinets would be perfect for you. You would recoup the cost in no time if your screens are causing you that much trouble.
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Sup guys... just breaking all the rules.... lol
(http://www.graphicdisorder.com/bstuff/IMG_3509.JPG)
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Honest question, was the screen out in the light that whole time?
The test that I've seen conducted is to leave a coated screen out on a table (completely exposed) with a coin(s) taped on the screen. Then after X days wash it out and see if the coin spot washes out differently than the rest.
You can take this further and put multiple coins and remove one a day blah blah blah to see the time frame that it took.
If you screens are/were in a cabinet or stacked or anything that would "shade" them, that could be a difference. Plus, you didn't have the coin on there and getting it to expose fine is relative as Dan has been pointing out. ;)
ME ME ME ME ME I can answer this one!!!
Before I had a covered rack, I used to coat around 10-12 screens stacked on a table separated by small sticks (for air flow) and a small fan.
One night I forgot and left the lights on all night, so the once-wet screens dried and then were under the florescent lights.
Next morning, before putting in a box (for static darkness) and thinking no problemo, I needed to expose a screen.
Taking the one from the top, following normal exposure times.....nothing......all solid.
Thinking - "that's odd" - grabbed another and same thing.
Now thinking emulsion problem and with some frustration and more than a little pissataion, I went to screen 3. Hey, I got a little image, but still unusable.
Finally using screen 4 from the top I got a working image.
Hypothesis - Yes, I can coat and expose in normal lights. But, No, I cannot leave the dried screens sitting out under normal lights (for a yet undermined number of HOURS - not days).
I think, for me, I have no problem with wet emulsion (while coating) under normal lights and brief periods (while taping for exposure) under normal lights.
That's my story and I'm sticking to it.
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Hmm... thanks BUT, I was wondering about Mr. 99.999999999% UV proof guy's lights. ;)
We know that all lights have SOME UV, hence why they sell UV blocking sleeves for these. I've just heard that the clear ones are OK, but don't block all of it (can go a few days like you had) and the amber ones can go a couple weeks as they block more. I'm sure there are red ones that do even better but I can't say really as I haven't heard anything about them.
I wonder if anyone makes UV blocking sheets (clear) that I can lay in my fluorescent panels vs buying a bazillion little tubes.
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Hmm... thanks BUT, I was wondering about Mr. 99.999999999% UV proof guy's lights. ;)
We know that all lights have SOME UV, hence why they sell UV blocking sleeves for these. I've just heard that the clear ones are OK, but don't block all of it (can go a few days like you had) and the amber ones can go a couple weeks as they block more. I'm sure there are red ones that do even better but I can't say really as I haven't heard anything about them.
I wonder if anyone makes UV blocking sheets (clear) that I can lay in my fluorescent panels vs buying a bazillion little tubes.
What about them? I just told you that I had a screen sitting on top of a rack for 6 months, not a few weeks. I removed the film from the other job and it burned fine no other portion of the image from the other film showed up. So do the math. light on in the screen room for 12+ hours a day within a few feet of said screen for at least 6 months and it burned just fine.
We tested these lights well before using them in the screen room. That 6 mo old screen verifies that there is minimal if any UV light affecting the screens. I had a photographer buddy come over and measure it. Virtually no UV light present. Not bad for a 10 dollar bulb pre-coated with a UV block.
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Hmm... thanks BUT, I was wondering about Mr. 99.999999999% UV proof guy's lights. ;)
We know that all lights have SOME UV, hence why they sell UV blocking sleeves for these. I've just heard that the clear ones are OK, but don't block all of it (can go a few days like you had) and the amber ones can go a couple weeks as they block more. I'm sure there are red ones that do even better but I can't say really as I haven't heard anything about them.
I wonder if anyone makes UV blocking sheets (clear) that I can lay in my fluorescent panels vs buying a bazillion little tubes.
Just get a couple of sq. ft of this stuff. Cut it down to size and you are sorted. We have used a similar product which worked just fine.
http://www.snaptint.com/product.php?productid=16192 (http://www.snaptint.com/product.php?productid=16192)
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Hmm... thanks BUT, I was wondering about Mr. 99.999999999% UV proof guy's lights. ;)
We know that all lights have SOME UV, hence why they sell UV blocking sleeves for these. I've just heard that the clear ones are OK, but don't block all of it (can go a few days like you had) and the amber ones can go a couple weeks as they block more. I'm sure there are red ones that do even better but I can't say really as I haven't heard anything about them.
I wonder if anyone makes UV blocking sheets (clear) that I can lay in my fluorescent panels vs buying a bazillion little tubes.
What about them? I just told you that I had a screen sitting on top of a rack for 6 months, not a few weeks. I removed the film from the other job and it burned fine no other portion of the image from the other film showed up. So do the math. light on in the screen room for 12+ hours a day within a few feet of said screen for at least 6 months and it burned just fine.
We tested these lights well before using them in the screen room. That 6 mo old screen verifies that there is minimal if any UV light affecting the screens. I had a photographer buddy come over and measure it. Virtually no UV light present. Not bad for a 10 dollar bulb pre-coated with a UV block.
For the record... that isn't what you said.
I just used a 305 last week for a job that has been sitting in there fo 6+ months and it exposed just fine.
That could have meant it was at the bottom of a rack of 20 screens for all I know. I'm not saying I don't believe you, quite contrare. This whole thread is juxtaposed against all of the variables that make it so hard to test. I just wanted some clarity on the variables in your case.
I'd like to get a source on those bulbs actually.
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Hmm... thanks BUT, I was wondering about Mr. 99.999999999% UV proof guy's lights. ;)
We know that all lights have SOME UV, hence why they sell UV blocking sleeves for these. I've just heard that the clear ones are OK, but don't block all of it (can go a few days like you had) and the amber ones can go a couple weeks as they block more. I'm sure there are red ones that do even better but I can't say really as I haven't heard anything about them.
I wonder if anyone makes UV blocking sheets (clear) that I can lay in my fluorescent panels vs buying a bazillion little tubes.
Just get a couple of sq. ft of this stuff. Cut it down to size and you are sorted. We have used a similar product which worked just fine.
[url]http://www.snaptint.com/product.php?productid=16192[/url] ([url]http://www.snaptint.com/product.php?productid=16192[/url])
Thanks!
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We took note today of the color of emulsion of the old bucket vs the brand new bucket. Couldn't' notice any real color difference there either. Food for thought. The old bucket has been opened several times in direct light to coat new screens. BTW in both floresnt light and our metal hialide lights in the print section of our shop, I do have high ceilings but still.
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we get a lot of sunlight in the shop, i personally wouldn't take a chance, but that is me and our situation. If we didn't have skylights, then maybe, but hte dust is also worse out there.
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we get a lot of sunlight in the shop, i personally wouldn't take a chance, but that is me and our situation. If we didn't have skylights, then maybe, but hte dust is also worse out there.
Just often coats with 2 garage doors open. One of them is massive and letting a lot, and i mean enough light not to have lights on if you want.
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that's the way it is here, under one of the skylights it's dang near as bright as it is outside. It will cure a screen in no time.
is the dust bad in your shop?
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that's the way it is here, under one of the skylights it's dang near as bright as it is outside. It will cure a screen in no time.
is the dust bad in your shop?
Dust isn't too bad but we also dry our degreased/emulsioned screens in air-filtered, Vastex DRI-VAULTS (35 slots) w/ built in dryers, so that part is never an issue really.
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OK, I gotta ask, those of you with actual screen/dark rooms- why are you coating on the linty shop floor in daylight and carting the screens back to the screen room?
Irregardless of whether or not the diffuse, ambient light of your shop screws up the liquid emulsion you are still 'exposing' that screen to all sorts of possible contaminants and then 'exposing' yourself to carting them back to the screen room for no good reason.
You are of course also literally exposing those screens, it's photosensitive emulsion and yes, it's light sensitive even when wet, just to a lesser degree. Perhaps much less, so much less that it's not even relevant how much light hits it wet, but I still don't see why you would not just coat in the room where the screens are going. And those of you who don't have the space for a screen house. our previous shop had no screen room but I made the whole damn shop a light safe room when I coated and handled screens.
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My shop has UV sleeves on all the lights and depending on the time of day I will roll the door down when handling screens
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I think it's convenience and simply that it doesn't make a visible dent in the everyday quality.
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Anyone ever obtain any results as a test from using a fresh bucket (inside the safe light room for a week or two versus coating out in regular light?
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Anyone ever obtain any results as a test from using a fresh bucket (inside the safe light room for a week or two versus coating out in regular light?
As soon as things get back to normal around here I am going to do some "spearmintin" and will report my findings.
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Dan I am about half done doing my test alas we are busier than a bees nest under attack right now.
I have developed the screen with the emulsion coated in the flouro lights already, it is a 260 and I nailed all the details in the macdermid exposure calculator, also I noticed not one issue with any of the screens that were used with emulsion coated in the flouro lights.
I have a safe light room for coating and developing screens but for this test I purposely went out in the open.
Maybe today or tuesday I will burn the 260 screen that was coated solely in the safe light room.
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DotToneDan wrote me last night asking my opinion.
Hello Richard,
I wanted to send you a link from our forum (Theshirtboard) where we are debating the affects of open light in a shop on wet emulsion while coating.
My theory is that as you get to the end of the gallon or 5 gallon bucket, you could be affecting the fine detail of say a 53-5% in a 60l line screen due to pre-exposure over a long time.
A few have said that they read where you mention that it's ok and harmless. Can you elaborate on this?
Is it totally safe in all cases of lets say extreme detail or is it figuratively speaking, about 95% of the time safe on most jobs?
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I assume Dan meant 3-5% 60 line dots.
I couldn't deal with this question until 4:30p and 3 1/2 hours later, I've read all 90+ posts. I spent some time trying to figure out who Inkman996 is and was surprised there was a Rick Roth in MIchigan - until I looked read his signature at the bottom of his post. I'm proud to see old contacts Zoo City, Alan802 although Alan didn't bring me the Round Rock Donuts I told him I needed bad, last year when I spoke in Austin at the Printwear Show.
I have more than 60 notes on details in those 90+ posts as discussion was very broad with answers targeted at tenderfoot printers with no money, to state of the art printers that use DotToneDan separations.
A stroke retired me overnight in 2009, so I don't have a screen room to experiment in, but I don't think this is too hard to test.
Every shop has unique ambient work light, so that's a variable stat isn't standardized - but who really cares what works in other shops?
How long do you expose open buckets?
I would pour 2 inches of fresh emulsion in a shallow container and let it sit for the test time - 1 hour? 3 hours? You have to stir, or the surface will skin and spoil your test.
Coat and dry test screens as equally as you can.
Expose one of each with identical positives as the glass & lamp heats up.
Develop at the same time.
You can now judge your areas.
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Can we coat out in the open shop or should use a screen room?
Can we? This is the first mistake. Can I jump out of this window? Can you?
Or..., should I make an effort to protect the tool we reproduce image with from threats that will make it fail?
Alas, this is America and you must do as you wish. Everybody's emulsion instructions explain: "XXXXX should be handled only under yellow safe light conditions" but some of you are asking how can I skate on this thin ice without failing?
As with all dangerous practices that our mothers & teachers have warned us about - like , not taking your blood pressure medicine, safe sex, pregnancy or driving home from the tavern - sometimes you can get away with shortcuts and doing it your way instead. Strokes, babies and car wrecks are more life altering than a spoiled screen.
No Room?
You have room if you're coating screens now. Build a tent of clear plastic or more expensive welding curtains over a light wooden or PVC pipe frame.
(http://www.richardgreaves.com/images/sp/ScreenRoomweldingcurtains.600w.jpg)
Monitor your exposure
After an exposure mistake I ordered EVERY positive with halftones or fine lines less than 0.020" must have a control guide the screen maker can see to judge if the stencil is correctly exposed. All tonal positives MUST have a halftone dot gray scale which is easy to add these days in Illustrator or CorelDRAW.
(http://www.richardgreaves.com/images/LineGage.143h.jpg)
As I was raised in a house with a dark room, I don't believe I've ever exposed a stencil without a U$10 21 Step Gray Scale.
(http://www.ulano.com/images/exposure/Stouffer21StepTransGrayScale.407w.jpg)
It's a 5.5" film positive that is opaque on one end and clear at the other, with 21 measured steps in between.
The 21 steps, simulate 21 different exposures. You get visual feedback so you can make clear judgments about exposure without guessing. Aim for a Solid Step 7.
(http://www.ulano.com/images/exposure/Step7grayscale.150h.jpg)
These test are basically free.
Dinner calls. I will post more tomorrow.
Richard Greaves 646-807-8580
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I am certainly satisfied with Richard's opinion of the matter. I was hoping he would chime in here. There are only a handful of guys in this industry that when they tell me something, I don't question it, I just do it and never look back, Richard is one of those guys.
I'll get you some of those donuts some how, some way, some day, it's a promise.
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I'll get you some of those donuts some how, some way, some day, it's a promise.
I'm sure those donuts would be stale by now!
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I performed the test following dans conditions exactly. I opened and used a brand new gallon of emulsion thought the week I coated solely in the open lights of our rear shop. Near the end I coated a 260 tpi screen.
At the beginning of this past week I was able to use that screen for a job and I not only exposed the art film but the macdermid calc as well. Thursday I repeated the process with a 260 that was coated in our safe room like always.
Using a loupe I cannot tell the difference between the two screens, both optimal targets on the scale held all the half tones perfectly.
I did take photos using an iPhone resting on the loupe but alas after checking them on the pc one picture was quite fuzzy, I am planning on bringing in my much better digital camera Tuesday to get proper shots to post here and show what my results are.
I truly feel what I did is exactly what is being discussed here, a typical shop that has no safe light and coats out in the open. I know this is still a lesson in futility because there will still be nay Sayers and some how find fault with my testing. Be that as it may I feel good with my test.
Disclaimer. I do have a safe room with fully protected fluorescents, not only is this room used for coating but also exposing and storing of screens.
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Water interferes with photochemical crosslinking
When a stencil is exposed, the sensitizer molecules absorb invisible UV energy and causes the atomic bonds to lengthen and split apart and bond to the atomic groups in the stencil polymer called hydroxyl groups.
All water molecules contain the equivalent of one hydroxyl group. During exposure the sensitizer molecule will bond to the nearest hydroxyl group and if that group is part of a water molecule the polymer cross-linking is wasted because cross-linking to water won't make the stencil water insoluble.
The sensitizer reacted, but wasn't used, like blanks - not bullets. If this happens too much (like when you add too much plasticizer to plastisol ink), the stencil will breakdown with water and fail - too many molecules not doing their job.
This the reason diazo emulsion ages when wet. Manufacturers warn that diazo sensitized emulsion will not react like a fresh sample 4-6 weeks after you sensitize it.
Photopolymer sensitizers work different and aren't effected by water as diazo is. At the factory, the photopolymer sensitizer is actually grafted to the Poly Vinyl Alcohol (PVOH) molecules in a sophisticated reaction. PVOH is the component that reacts with a sensitizer to "harden" the emulsion, giving it the ability to resist dissolving with water.
When exposed to UV energy, the photopolymer chains begin to seek each other out. They are very fast-acting, but short-lived. If they do not find each other and form a bond very quickly, they to can become completely ineffective, but their nature makes them very easy to react and join up. Longer exposure doesn't encourage more crosslinking of stubborn photopolymer sensitizer like with diazo.
Plastisol vs. Solvent or Water-base Inks
Plastisol ink is like salad dressing and harmless to stencils. This means that the most poorly exposed stencil (if it survives development), will survive a print run.
Using dragon breath solvents to clean up meek little plastisol, is playing with fire that will damage your stencil, especially if it's under exposed.
Water will break down under exposed stencils. It is the major component of the emulsion itself and if you don't expose it with invisible UV energy, it won't resist the natural desire of water to dissolve your stencil and rinse it down the drain.
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I decided to post up the two photos taken, if any one wants to see a non blurry one I can accommodate but I think even tho it is blurry it is still good enough to see how well it developed.
First is the 260 screen coated in a normal flourescent lit shop with some day light leaking in.
(http://i76.photobucket.com/albums/j35/inkman996/4363559b.jpg)
This one is a 260 coated one week before the first in a safe light room and stored beneath a shelf out of any direct.
(http://i76.photobucket.com/albums/j35/inkman996/2b331158.jpg)
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Inkman996.
(http://www.richardgreaves.com/images/sp/AutotypeAEC.350w.jpg)
Do you mean the classic Autotype Exposure Calculator when you write "macdermid calc"?
I worked on the re-design in the early 1990's.
Have they changed it in the last 3 years?
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That is it. I have used that one since about 95 when working for a screen company. Just bought a new one a few months back.
http://www.sourceoneonline.com/item.asp?categoryID=0§ionID=0&subSectionID=0&subSection2ID=0&subSection3ID=0&attrCatID=0&attrIDs=0&searchtext=Macdermid&catID=45&catTab=&productID=572 (http://www.sourceoneonline.com/item.asp?categoryID=0§ionID=0&subSectionID=0&subSection2ID=0&subSection3ID=0&attrCatID=0&attrIDs=0&searchtext=Macdermid&catID=45&catTab=&productID=572)
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Yellow Lamps
I've been in 6 emulsion factories. They all process, pour and package under gold fluorescent lamps.
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I'll get you some of those donuts some how, some way, some day, it's a promise.
I'm sure those donuts would be stale by now!
If you are ever passing down I-10 through Lafayette, LA look me up... I will ruin every other donut you will ever have by giving you the pleasure of a Meche's donut. Practically melts in your mouth, oh I need me some Meche's now!
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If you are ever passing down I-10 through Lafayette, LA look me up... I will ruin every other donut you will ever have by giving you the pleasure of a Meche's donut. Practically melts in your mouth, oh I need me some Meche's now!
I have been to Kaplan, LA (via Lafayette) many times, and once participated in the Mardi Gras parade. As I don't drink alcohol, I do remember the fantastic donuts the motel owner recommended. Everyone seemed to smirk at my odd Northern ways, but I'm afraid I must insist you bring some to Las Vegas for the SGIA Show.
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I've thought about trying to go to that show... still not sure it makes sense logistically.
Besides, the donuts wouldn't be fresh and there is a HUGE difference between a FRESH HOT Meche's donut and well... anything else including a Meche's donut that isn't hot and fresh. When the heat leaves, the magic leaves.
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Hmm... thanks BUT, I was wondering about Mr. 99.999999999% UV proof guy's lights. ;)
We know that all lights have SOME UV, hence why they sell UV blocking sleeves for these. I've just heard that the clear ones are OK, but don't block all of it (can go a few days like you had) and the amber ones can go a couple weeks as they block more. I'm sure there are red ones that do even better but I can't say really as I haven't heard anything about them.
I wonder if anyone makes UV blocking sheets (clear) that I can lay in my fluorescent panels vs buying a bazillion little tubes.
Just get a couple of sq. ft of this stuff. Cut it down to size and you are sorted. We have used a similar product which worked just fine.
[url]http://www.snaptint.com/product.php?productid=16192[/url] ([url]http://www.snaptint.com/product.php?productid=16192[/url])
Just wanted to dig this up and follow up on it.
I got some samples of the snaptint stuff and laid it under a corner of my exposure unit staggered the 4 sheets that the sent me. When I washed out I put the garden hose on jet (how I develop my exposed screens) and I hammered on that corner (about 16 square inches) where I had laid those sheets AFTER I developed the rest of the screen and didn't get a single bit of emulsion breaking down.
So I'd have to say that whatever UV these sheets are blocking have NOTHING to do with our emulsion. :(
35 light units on an older MSP 3140.
Still looking for sheets because I have SIX 2x4 panels in my production area that hold four T8 bulbs each. :(
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Gilligan, if your panels have diffusers on them, I've got a roll of 24" wide Rubylith I'll sell you for real cheap, to cover them. It'll give off a nice safelight red glow. :D
As Mr. Greaves stated about the yellow light that's probably the best bet.
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LOL... if it was only a small room, I'd take you up on that... but this is the entire production area.
My guy would come out all messed up if I left him in red lights that long. :)
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fluorescent lights aren't that bad for screens. I wouldn't worry about it unless you get a lot of sunlight. You could always do a type of curtain.
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My screen dept is overkill perhaps but is divided up into seven different rooms (and four different sinks); each with its own environmental properties. I think Richard might have said it best when he said we have some areas where the atmosphere is similar to the Amazon and others where it needs to be more like the Sahara.
Which is why each has it's own light, temperature, humidity, and air filtration requirements and are isolated from each other. This, to me, will yield optimum results and remove questionable variables from the equation.
That said when I was visiting a shop on St Thomas where they exposed with sunlight I asked
"What do you do when it rains?"
The response was............wait for it........"Something else"