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screen printing => General Screen Printing => Topic started by: ericheartsu on February 01, 2013, 11:51:37 AM
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This year i'm trying really hard to work more efficiently. We recently switched to newman mesh panels on all of our frames and have been stretching our screens between 40 and 50n on our m3s, and 30n on our mzx square bars. We use Kiwo Discharge emulsion, and i've been doing a 2/1 coat, with the sharper edge of the scoop coater. I've noticed we've been getting crisper prints with the high tension frames and coating technique, but I still feel there is room for improvement.
We use an older M&M Xpress Auto, and soon we'll have our Gauntlet S (pneumatic) press up and running too. Now my question pertains to the title of this post, How should i be judging our squeegee and floodbar angles and pressure? I feel alot of time, we are hitting each color twice, as they are not clearing the first time at lower speeds/heavier pressure. What can we do to get the press to start clearing quicker?
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A lot of times what printers think is a squeegee angle/pressure problem and having to double stroke is really a mesh count selection issue. Sure, you can change squeegee angle, speed, pressure, etc. to go from 2 strokes to one, but most of the time the dreaded double stroke is due to the wrong mesh selection. But to answer your other questions I've always been able to print pretty much anything with our regular squeegees at about a 70-80 degree angle. Our smiling jacks and other variations of Joe Clarke's blades are set to 88-90 degrees when using the beveled edge and around 80 degrees when using the sharp edge. If your press has squeegee air regulators then you can control the amount of pressure in the chopper cylinders and essentially have full control over how much pressure you're printing with. A thicker white plastisol through a 110/81 mesh at our shop takes about 20psi on the squeegee pressure and regular plastisol through a 305 will be somewhere in the 35-40psi. Those are two extremes and every press is a little different but our numbers can get you in the ballpark to start testing.
Flood angle isn't as critical but we've always moved the floodbar to give us about 3" of ink well between the sq and fb. We use a hard flood to fill in the stencil so that we can print with less pressure, but you'll find that many great printers do not flood hard and don't even have the bar touching the mesh and still get great results. They will be using slightly higher pressure than I will be but it's not a big deal. I have the fb set to where it's touching the mesh and you can feel the fb when rubbing the underside of the screen with your hand. You don't want to flood too hard though so you have to find that sweet spot.
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We have ZERO knowledge about autos, strictly manual prints but I would suggest investigating /testing a different coating method from what you describe.
Initially we coated much like you detailed. Through evolution time and a lot of frustration we ended up coating 3 /2 with a wide edge coater.
Improved the stencil EOM a bunch therefore better sealing around the print with more ink where we want it to be.
Baically our 3/2 method is the glisten method, we just keep hitting the screen until we have a heavy & full deposit of emulsion through the screen, usually 3 passes. Then hit it twice to finish up.
Bottom line coat two screens of the same mesh one with you current method and one with something you decide to try produce a stencil do some printing and see what you see. the results will tell you what direction to go next relative to coating.
Again we have ZERO experience with an auto but an optimum stencil (whatever that is ) is a big move in the right direction.
mooseman
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This year i'm trying really hard to work more efficiently. We recently switched to newman mesh panels on all of our frames and have been stretching our screens between 40 and 50n on our m3s, and 30n on our mzx square bars. We use Kiwo Discharge emulsion, and i've been doing a 2/1 coat, with the sharper edge of the scoop coater. I've noticed we've been getting crisper prints with the high tension frames and coating technique, but I still feel there is room for improvement.
We use an older M&M Xpress Auto, and soon we'll have our Gauntlet S (pneumatic) press up and running too. Now my question pertains to the title of this post, How should i be judging our squeegee and floodbar angles and pressure? I feel alot of time, we are hitting each color twice, as they are not clearing the first time at lower speeds/heavier pressure. What can we do to get the press to start clearing quicker?
Sam from Palomar told me to coat my screens 2/2 with the rounded/soft edge. It improved my printing a ton. I was coating my screens 1/1 with the sharp edge. I have a diamondback. Try it out, hope that helps you.
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Are there still a lot of printers that aren't familiar with the Glisten Method of coating screens? We could start a thread on coating screens for proper EOM but I thought it was out there and known by most. It's essentially the method Kiwo, Ulano and a few other emulsion companies recommend using for their emulsions.
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honestly the reason why we've been doing it this way, is it seems that every other way, our films stick to our screens. We use a epson 1400 and 9600, both with accurip. And when the films stick to the screens, it pulls the ink off of the films, and it makes it super hard to get out fine lines and halftones because we the ink jet ink on the screen.
This is after letting our waterproof film sit for an hour or two, and in most case the screens have dried anywhere from 8 to 36 hours in a room that is about 73 degrees, with a dehumidifier running!
so maybe thats our problem?
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What emulsions are you using? Also what film?
We have used emulsions in the past that, no matter how long they dried, would still pull the ink
off the film. Couldn't figure it out for the longest, but eventually switched emulsions and
the problem went away.
Aquasol HV and Fixxons film printed with dye based inks and we don't have this problem.
We coat 2/2 round edge for most mesh counts and applications.
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I know for me, i use the saati textil pv emulsion...For my screens to come out right it needs to be more than 73 in there..I keep it in the high 80's ...Im in the northeast so pretty much only use the dehumidifier in the summer months..
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We are using the Kiwo Discharge emulsion, and Fixxons films.
I know we've always had this issue with Kiwo, but even when i was using CPTEX, i believe i was having the same issue.
Oddly enough, on our graphics screens, we use Kiwo Poly plus S, with a 2/1 sharp side of the scoop coater, and those NEVER stick. but granted that emulsion is for waterbased acrylic and uv ink
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Our emulsion pulls the ink from film no matter what the conditions are so we use baby powder. It does it on most pure photopolymer emulsions with decent EOM. All of the dual cure emulsions we've tried do not pull the ink from film. I think the only PP emulsion that didn't need the baby powder technique was PC 701, but that was a long time ago and I can't recall for sure.
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We've tried the baby powder trick and i've found that it always, just makes even more of a mess, without an added benefit.
I feel like i've been getting great EOM recently, but i still need to buy one of those gauge thingys.
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I wonder if it has anything to do with yous guyses relative humidity down there.
The only time we have issues is if we don't let the film dry out for awhile.
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if your films are still sticking even after powder you really must have some humidity problems or you are under curing the screen?
just for shirts & giggles get some PAM cooking oil spray, spray it on a towel and wipe down the screen lightly just to see if you get any improvement.
We had real sticking problems with Ulano QTX and waterproof films (all brands) the powder solved the issue 100%.
We throw it on, the powder, wipe by hand or a towel get a good overall coverage and it always works.
mooseman
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if your films are still sticking even after powder you really must have some humidity problems or you are under curing the screen?
just for shirts & giggles get some PAM cooking oil spray, spray it on a towel and wipe down the screen lightly just to see if you get any improvement.
We had real sticking problems with Ulano QTX and waterproof films (all brands) the powder solved the issue 100%.
We throw it on, the powder, wipe by hand or a towel get a good overall coverage and it always works.
mooseman
I feel like i've dialed in our settings on our exposure unit, i've done a couple of different tests with the calculators to make sure, so i don't think undercure is the issue
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I've never had this problem and am curious as to why so many others apparently do
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You only use diazo and/or dual-cure Tony?
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Yes. We can shoot four auto screens at a clip so the extra time doesn't matter. Will be beta testing the new CCI stuff which is faster.
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I think diazo has a lot to do with it, but what do I know, I ain't no chemist.
Let us know about the CCI. We'll be making another foray into the diazo world.
The time involved was never a problem in terms of getting screens out, it just drove
me nuts coming from photopolymers.
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We've tried the baby powder trick and i've found that it always, just makes even more of a mess, without an added benefit.
I feel like i've been getting great EOM recently, but i still need to buy one of those gauge thingys.
I don't understand why it doesn't help. It completely prevents the film from sticking to our screens and besides some baby powder on your hand it doesn't make much of a mess. I wonder what's going on that it wouldn't help your problem.
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We've tried the baby powder trick and i've found that it always, just makes even more of a mess, without an added benefit.
I feel like i've been getting great EOM recently, but i still need to buy one of those gauge thingys.
I don't understand why it doesn't help. It completely prevents the film from sticking to our screens and besides some baby powder on your hand it doesn't make much of a mess. I wonder what's going on that it wouldn't help your problem.
maybe it's time we hire Alan the Consultant for the afternoon.
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The chemistry of the emulsion can have a big factor in film sticking to screens. I have a CCI emulsion that is terrible on lower meshes ((110-220) and yes, CCI recognizes that this is a problem with that emulsion) that will pull off the ink from my films... even old films. I am trying out the Murakami AquaSol HV and having none of those issues. We also have Humidity in the 32%-38% range in our screen room, low 70's for temp. We are in Beaverton, just outside of Portland. I have seen this before with outher emulsions.... Hate to say it, but try a different emulsion. Anything else is a bandaid.
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if your films are still sticking even after powder you really must have some humidity problems or you are under curing the screen?
just for shirts & giggles get some PAM cooking oil spray, spray it on a towel and wipe down the screen lightly just to see if you get any improvement.
We had real sticking problems with Ulano QTX and waterproof films (all brands) the powder solved the issue 100%.
We throw it on, the powder, wipe by hand or a towel get a good overall coverage and it always works.
mooseman
I feel like i've dialed in our settings on our exposure unit, i've done a couple of different tests with the calculators to make sure, so i don't think undercure is the issue
I think he was talking about drying your screens thoroughly, but I could be wrong.
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if your films are still sticking even after powder you really must have some humidity problems or you are under curing the screen?
just for shirts & giggles get some PAM cooking oil spray, spray it on a towel and wipe down the screen lightly just to see if you get any improvement.
We had real sticking problems with Ulano QTX and waterproof films (all brands) the powder solved the issue 100%.
We throw it on, the powder, wipe by hand or a towel get a good overall coverage and it always works.
mooseman
I feel like i've dialed in our settings on our exposure unit, i've done a couple of different tests with the calculators to make sure, so i don't think undercure is the issue
I think he was talking about drying your screens thoroughly, but I could be wrong.
most of our screens sit for a minimum of 10 hours before being made. usually its a full 24-36 hours.
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BTW, I'm sure it's not related as we have the EXACT same issue and we leave ours for at least that long if not longer (slow shop ;) ).
We use Chromaline Blue and even with powder we can have issues, but that's probably due to not enough powder.
Maybe I need to hire this guy:
(http://technicolored.files.wordpress.com/2008/11/baby-powder.jpg?w=510)
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We've tried the baby powder trick and i've found that it always, just makes even more of a mess, without an added benefit.
I feel like i've been getting great EOM recently, but i still need to buy one of those gauge thingys.
I don't understand why it doesn't help. It completely prevents the film from sticking to our screens and besides some baby powder on your hand it doesn't make much of a mess. I wonder what's going on that it wouldn't help your problem.
maybe it's time we hire Alan the Consultant for the afternoon.
Is the Kiwo Discharge a dual cure or full diazo? I know your humidity levels are higher than ours but even under the most controlled room our pure photopolymer emulsions do this without baby powder. 30% humidity, drying for days, both screens and film and it will rip the ink off if we don't use the powder. Dual cures don't do this, but I've never tested a pure diazo emulsion so I can't say if it acts like the PP's do.
Seriously though, the baby powder rubbed generously over the screen does not stop the sticking issue?
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Try a gallon of Aquasol HV, 2/2 coat with the round edge, and adjust your exposure a little for the extra thickness.
No reason you shouldn't be getting a one hit. Maybe post a video of a flood print for a couple cycles so we can get an idea of speed, pressure, ink slough, etc.
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We had the sticking problem with the textile PV, usually in the summer. Also had the same thing with a CCI red diazo (name slips me now). I would just spray a light coat of clear window frosting over the film. Let it dry for a few min and all was well. We have been using the Kiwo Discharge for a month or so now and no problems with the sticking and I have been rushing screens out of the dry box, shooting them in less the three hours after coating. Maybe it will change once the weather starts getting a little hotter. pGoing to give the quart of WR-14 we got last week a try later this week.
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I used to have a bad problem with the old Ulano film & ink sticking to the Kiwo Polyplus HWR, but switched to a dye-based ink & film, & it stopped completely. Occasionally, a piece of film will stick a little bit to a screen that's not fully dry, but it no longer pulls the ink off.
We use Chromaline UDC 2 for plastisol, mainly for the fine detail I get with it, & coat it 2/1 dry, then coat again twice on the outside for a smooth finish. On the HWR for discharge, we do a 2/2 with no second coat.
We also keep a dehumidifier running on the screen rom pretty much all the time. As this is Texas, it barely keeps the humidity between 40-50%. I'd prefer that screens dried overnight, but when we're busy, and hour or two is usually fine.