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screen printing => Newbie => Topic started by: Appstro on January 17, 2014, 03:37:59 PM
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Thanks in advance for your opinions. I will try to put every detail I can here so you can tell me if I did something wrong.
Washed screens
Envirowash
Dehaze
cleaned again with laundry detergent liquid
let dry two days
Coated screens
1/1
put fan on them
let dry overnight
Did a wedge step test on my exposure unit.
1 minute exposures up to 8 minutes
washed out wedge test
1 minute-no good
2 minute-no good
3 minute-iffy
4 minute- looked better
5 minute-missing elements
6 minute-looked acceptable
7 minute-looked great
8 minute looked great
printed film straight from illustrator using 100/100/100/100 black
exposed for 6.5 minutes as that seemed like the best time
Used hose sprayer to coat moth sides of screen with water well.
waited a minute for water to soak in a bit.
Used pressure washer holding tip about 18-24 inches away from surface of screen.
Washed in sweeping motion.
Looked good after 10 seconds or so,…..then began to blow out immediately.
I figured screen was underexposed..
New screen. Exposed for 10 minutes….
Same wash procedure…
Looked great at first
Set out in sun to dry and post expose
Then I looked at the screen and here is what I had. i went ahead and used it and used block out to fix what I could. I did 20 shirts and when I cleaned up the screens with plastisolve the emulsion started coming off the screen. 1st screen was 110 second was 150. What do you think happened?
I am also wondering why my used exposure unit could be taking so long to expose. Its the Ryonet 20x24 unit. How can I tell if my bulbs are worn out?
(http://i259.photobucket.com/albums/hh309/appstro/DSC03458.jpg)
(http://i259.photobucket.com/albums/hh309/appstro/DSC03459.jpg)
(http://i259.photobucket.com/albums/hh309/appstro/DSC03460.jpg)
(http://i259.photobucket.com/albums/hh309/appstro/DSC03461.jpg)
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that doesn't look like 110 mesh ? far too course more like 80?
Was it brand new a brand new screen? new mesh? because I have had something similar happen with new or newer low mesh count screens, Also you may need to coat 2x on the shirt side and 1 hard one on print side, Also was it humid or not fully dried? and exposure time may also not be long enough.
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laundry soap? :o ...what emulsion? 2/2 or glisten method is best -for my shop anyway- looks way underexposed.
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looks way underexposed.
x 2
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x13
I remember fluorescents taking like 30 minutes with Speedball diazo emulsion.
Which emulsion you using?
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cleaned again with laundry detergent liquid
Why would you do this?
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I probably shouldnt have used the liquid laundry detergent... At the time I thought it would be a good degreaser. I have since been told that Simple Green would be better.
The photo's are super close up. That whole area is only 4 inches wide. Its the pocket logo.
The emulsion is pro chem DXP pink.
What is the "glisten method"??
I am starting to think its the bulbs.... Ryonet says that it should take 5.5 minutes to get full exposure with new bulbs...
The screens were 150 and 110 mesh that I had to clean. I bought the whole unit used from a guy that decided to quit.
Not humid here is San Diego. I coated the screens following the directions in a few videos online. I remember thinking that the emulsion seemed thin to me once it was cured on the screen, but I am not 100% sure what it should look like so...
If I do 2/2 method or 2/1 method, do I let the 1/1 dry first then recoat or do all at the same time?
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It's underexposed.
And there is really no reason to degrease.
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glisten method is basically coating a few times on the shirt/substrate site first, until you see the squeegee side 'glistening' or shining. and then coat the squeegee side. Takes a bit of practice, but ultimately you want to get enough emulsion over the mesh vs just in it.
your pics look like the emulsion was quite thin.
I agree that it definitely looks to be under exposed.
once you get a proper exposure, you should be able to soak your screen in water after exposing it for a long time without any bad results...
how did the squeegee side feel after wetting the screen? Betting it was slimy... a sure sign of under-exposure.
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Is this a good bulb instead of the ryonet $20.00 bulbs... seems like the same thing...
http://www.amazon.com/GE-35884-F15T8-Fluorescent-Black/dp/B002CYXIEM (http://www.amazon.com/GE-35884-F15T8-Fluorescent-Black/dp/B002CYXIEM)
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for 110 we usually do 3/1 or 2/2 depending on a few things, though I would lean toward 3/1 if done properly. In the photos the mesh is poking out of the emulsion which means either the emulsion doesn't have enough solids to sit in the mesh, or there simply isn't enough emulsion on the screen.
I am also seeing a lot of undercutting (blurry edges) AND underexposure, which means your exposure setup likely isn't adequate to properly expose your emulsion. Doing a proper coating will only make this problem worse as you will be adding additional thickness to the emulsion.
You should post photos and specs of the exposure setup you have as well if you have a chance.
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http://www.silkscreeningsupplies.com/product/RXP2024 (http://www.silkscreeningsupplies.com/product/RXP2024)
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It's underexposed.
And there is really no reason to degrease.
Thank you for saying this.
I cannot remember the last time I degreased and I've been thinking I"M the oddball but I don't have an emulsion problem using QTX and 2 + 2 coat.............as long as the emulsion is not OLD!
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I didn't realize how much I was under exposing until I got a real exposure unit.
Things SEEMED ok, but after seeing how a real exposure unit exposes I realized I was fighting under exposure. We almost can't screw up an exposure now.
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Without a vacuum top you will always fight exposure. I did the compression method for awhile and it was frustrating to say the least
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Oh wow... I hadn't even looked at the unit before.
Yeah, I was using a DIY setup with a vacuum storage bag and was still having issues.
Our MSP 3140 is my favorite tool in the shop!
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I still expose with daylight bulbs and an mdf and foam top with weights on it. I can expose a 110 mesh in 2:30 with 3/1 or 2/2 and serious eom, and I can expose a 280 with 60lpi in 2 minutes or less without issue. I also know my unit and emulsion, and have done proper testing. Obviously this isn't ideal, but it is more than usable. I should have my vacuum MH unit finished within the month though and definitely can't wait!
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I bought new bulbs today and they should arrive by the 25th so I will do another step wedge test then. In the mean time I am going to coat these screens one more time.
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out of curiosity, was the glass on the unit replaced? It's possible it was replaced with some kind of coated glass or acrylic which would block a ton of UV and mess up exposure. Just a thought if the new bulbs don't fix the problem. I'm still using daylight bulbs that are 5 years old without issue (lol).
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What is the "glisten method"??
http://www.theshirtboard.com/index.php/topic,2621.0.html (http://www.theshirtboard.com/index.php/topic,2621.0.html)
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AH! I will have to try that next time I do screens.
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Appstro try burning your screens a little longer, if your using dual cure I would burn about 8 to 10 minutes unless your screens are getting hot and if your going to under expose them wash your screen out very gentle, every thing you read is not real world, but a suggestion to go by..oh make sure your screens are free of any oils, emulsion just wont stick to them.
Darryl
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...you can tell me if I did something wrong.
Washed screens
Envirowash
Ok.
Dehaze
Ok but, with what dehazer?
cleaned again with laundry detergent liquid
Good lord. This could have drastic effects on your screens. Perfume and detergent residues, etc. Use a quality screen printing degreaser or just none at all. Many dehaze products get most all the gunk out of a screen. We use Easiway 701, a pressure rinse then a careful flood rinse. Screens are dead clean every time. I personally only use degreaser on brand new mesh and only once to get rid of factory grime and contaminants. Don't use Simple Green, it would just be a wasted step.
let dry two days
Excessive. In a warm (not hot) dry room with moving air you should be able to coat within hours.
Coated screens
1/1
If that works for you then stick with it, but I would try the glisten method mentioned above. You might need a stronger exposure system once you bump up the emulsion thickness though. If you are already having exposure issues, thicker emulsion will only exacerbate the problems.
put fan on them
Nope. Some moving air in the room is fine but don't point it directly at the screens, you are only inviting pinholes from dust and debris in the air. My favorite combo is a small air filter to move the air around, and a dehumidifier to keep it dry. You know your screens will dry fast when the emulsion in the scoop coater dries on the edge of the coater blade faster then you can grab the next screen.
let dry overnight
Possibly excessive, depending on your humidity and temp.
Did a wedge step test on my exposure unit.
8)
1 minute exposures up to 8 minutes
washed out wedge test
1 minute-no good
2 minute-no good
3 minute-iffy
4 minute- looked better
5 minute-missing elements
6 minute-looked acceptable
7 minute-looked great
8 minute looked great
Let's go with "great"...
printed film straight from illustrator using 100/100/100/100 black
8)
exposed for 6.5 minutes as that seemed like the best time
Again, let's go with "great". The 7 and 8 minute mark were probably a better bet. If you are able to hold detail (not pinching off lines and text, etc) and the screen can stand up to a brisk washout during developing, then you are doing good. You shouldn't have to be too gentle on it and the stencil should hold up to a fair amount of water pressure. Push the exposure as far as you can and still hold the detail.
Used hose sprayer to coat moth sides of screen with water well.
waited a minute for water to soak in a bit.
Laying the screen(s) horizontal and keeping them wet for about 2 minutes works wonders. The emulsion should just about "fall" out of the stencil once it's been soaking long enough.
Used pressure washer holding tip about 18-24 inches away from surface of screen.
Washed in sweeping motion.
8) Good, but not knowing the pressure washer's capability, this can mean anything. I've used some you can't get anywhere near a stencil with (too strong) but the model I'm using at the shop now has an adjustable regulator at the pump, so I dial it way back for developing.
Looked good after 10 seconds or so,…..then began to blow out immediately.
I figured screen was underexposed..
Underexposed and/or covered in evil laundry detergent spookiness.
New screen. Exposed for 10 minutes….
I would personally fall on a wooden stake if I had to wait through a 10 minute exposure. That's just me though... ;D
Same wash procedure…
Uh oh...
Looked great at first
Set out in sun to dry and post expose
Then I looked at the screen and here is what I had. i went ahead and used it and used block out to fix what I could. I did 20 shirts and when I cleaned up the screens with plastisolve the emulsion started coming off the screen. 1st screen was 110 second was 150. What do you think happened?
See above....
I am also wondering why my used exposure unit could be taking so long to expose. Its the Ryonet 20x24 unit. How can I tell if my bulbs are worn out?
If you think they are, they probably are. If you are going to spend money on new lamps next time these wear out, I'd drop coin on an older used single point unit with a metal halide lamp that is made to put out serious UV energy. If you go down the replacement lamp path, always get quality lamps that put out the right light.
Also as mimo stated, make sure the glass on the unit is low-lead, optically clear glass. (most good glass shops will understand this requirement) Regular glass can actually filter out much of the UV energy that you want hitting the emulsion.
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I have to applaud you on your use of the "quoting" here. But God, it must have taken forever to put those all into one post, lol.
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Thanks for the replies. I will be getting the bulbs in tomorrow and doing a step wedge test. If the results are good then I will try to burn a screen and see what happens. Is there any way to tell if the glass has UV filtering or not by looking at it?
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Thanks for the replies. I will be getting the bulbs in tomorrow and doing a step wedge test. If the results are good then I will try to burn a screen and see what happens. Is there any way to tell if the glass has UV filtering or not by looking at it?
Depends. Do you have x-ray vision?
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The issue I see is underexposure. Exposure bulbs are like engines. There are ones with V8 strength and ones with lawn mower strength. A lot of starter system lamps are outgrown quickly as orders get larger or when looking into new ink systems. I have seem many mid sized shops that started out as hand printers and now have a couple of automatics and still using tiny fluorescent tube systems. While a large exposure system of 5,000 watts seems extremely expensive in the beginning, it's value is that you will have a hard time out growing it. Better halftones without underexposures, strong screens for any ink system, faster screen make ready, etc. All in all it is one of the best investments in your shop. The light is not chaotic like tube lamps, you will be able to expose excellent details at full exposure. It is amazing to me how the emulsion was blamed for breakdown by shops I have seen when they insisted on using fluo bulbs and exposing in 1/10th the time needed. For maximum performance you need maximum exposure. Underexposing with less light is kind of like filling up the tank with half a tank of gas and expecting to go as far as a full tank. Energy in = emulsion strength. For the system you have try a step test. Here's a link on how to perform you own. Even if two companies have the same exposure unit their times can be different due to humidity issues, lamp age, coating technique and emulsion used. I recommend Photocure BLU from Murakami for low wattage exposure units.
Step Test for do it your selfers: http://murakamiscreen.com/wp-content/uploads/2012/07/Step-Test-Instructions.pdf (http://murakamiscreen.com/wp-content/uploads/2012/07/Step-Test-Instructions.pdf)
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I did a step test and looks like I am still at about 8-9 minutes. The last screen I did worked fine. This time I hit it with the pressure washer quickly and tried very hard not to do too much washing. I then laid newspaper on the screen to soak up some of the water and laid the screen out in the sun to dry/cure for about 30 minutes. Screen printed no problem.
Still seems weird that in all the Ryonet videos the guy says 4.5 -5 minutes is the normal exposure time....I dont think so... not on this exposure unit anyway.
When its time to upgrade to a real exposure unit, keeping space savings in mind, what is the most widely liked unit for 20x24 frames?
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I expect what everyone has they pretty much like.
So I'll just toss mine out there and it works a helluva lot better than my old flood light setup with weights.
Workhorse Lumatron 6 bulb black light with vacuum lid.
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someone else linked to these in a recent thread and I bought a handful. They RULE and there is an easy formula to calculate proper exposure after the first test. I was able to dial my new unit in with three total tests which included changing the height of my bulb slightly to get the time exactly where I wanted it.
Here is where I bought mine: http://www.victoryfactory.com/tools.htm (http://www.victoryfactory.com/tools.htm)
Here is the formula: http://www.stouffer.net/using21step.htm (http://www.stouffer.net/using21step.htm)
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As far as exposure units, to me the king of all exposure lamps is the 8,000 watt from Olec, now sold by Douthitt.
It has incredible multi spectral light that can really expose emulsion to it's absolute strongest capability.
Nothing wrong with lower wattage units, just longer exposures.
Ballpark Times on a pure photopolymer emulsion Like Murakami Aquasol HVP on a 110 mesh.
8,000 watts: 30-45 seconds
5,000 watts: 50-80 seconds
1,000 watts: 2.5 - 3 minutes
Fluorescent tubes 8 - 18 minutes
Why the different times? for fluorescent tubes a lot depends on the manufacturer, the type of tube and the wattage of the tube, as well as age. Even two exactly the same units will expose at different times for the following reasons: Age of Bulb: the older the bulb the longer it will take to expose, newer ones will expose faster. That's why high end exposure units come with an integrator that measures lumens, not seconds, so that the screen receives the right amount of light for exposure.
What type of Bulb? Use original manufacturer's bulbs. They have more precious metals in metal halide lamps and last longer and have better multi spectral wavelength output. Also where your shop is located has a lot to do with exposure times. Low humidity areas like Phoenix AZ can expose far faster than the wet foggy climate of the beach in California or the tropics. The best way to look at a screen is you can easily make an image with underexposure but you can't make a strong screen, only a complete exposure up to but not at over exposure will create a strong screen to withstand difficult inks like discharge, HSA, or long run plastisol. Post exposure is the obvious fix or hardening, but is possible that important layers of emulsion were washed off during development on the inside of the screen that prevents stencil breakdown, or pinholes due to squeegee abrasion.
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I never thought about that with fluo tube units(I've never owned one), but you have to replace all the bulbs if one fails, correct?
Our 7.5K unit will do HVP in less than 30-45 seconds...coated with the glisten method.
I actually found that with HVP it was really hard to dial in since our unit won't allow decimals, we couldn't get it perfect and moved to CCI WR-14.