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screen printing => Screen Making => Topic started by: Dottonedan on March 16, 2016, 02:22:47 AM
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I came across a printer that actually practices the multi layer coating methods.
He had a stack of screens in a rack numbered 2,3,4,5. I asked about #5. "do you actually coat 3:2 or 4:1. He said oh no, that's for each side. 5:5.
305's were 1:1 round but everything else had multiple coats and face coats.
So I asked, do you PFP a white base? " oh no, never need to.
That bottom pick is a called a fat film. 600 micron on 30 mesh.
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I am a bit taken aback here, Just what is it I am looking at?.... First wouldn't 5/5 require a blast of light fringing on atomic mushroom cloud to get exposure? And that film on 30 seems like a sewer drain. What would be the purpose?
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Used mostly for high density/gel prints. Pretty much came and went but I come across it once in a while.
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Minor side track on this topic: does face coating help correct a dodgy or uneven first coat or just make it worse?
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So as far as ink usage goes, is it shirts per gallon or gallons per shirt? :P
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The 600 micron on the 30 mesh almost looks like a tarp with holes in it. That sure is a thick stencil.
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I am a bit taken aback here, Just what is it I am looking at?.... First wouldn't 5/5 require a blast of light fringing on atomic mushroom cloud to get exposure? And that film on 30 seems like a sewer drain. What would be the purpose?
SoccerMom,
I'm sure it does add more exposure time, but this customer is using an STE2 (LED panel on the back) and exposing a 3:3 coat on a 150 mesh using Pure Photo Poly at 60 seconds. He was getting a full exposure on both sides washing out with a high pressure wand. I myself, thought the screens were a little over exposed. (He's got exp times for each coat) on each mesh. The exposure times is not (as long) or as extra as you might think.
Integrity, In his case, they have long production runs and generally would rather put down more ink the firs time than to double stroke or Print Flash Print Flash again. More ink saved production.
Wildcard, Yes, A face coat does just that. After you've coated 1:1, let it dry, then come back to fill in the voids or vallies of the mesh threads. As emulsion dries, it sort of vacuum forms to the threads. This kind of tells you that you have too little emulsion on the screen. (Most shops have too little from what I see). If coated too thin, you get that waffle texture and uneven or less than smooth edges on angles sides of letters like the Letter A. This helps create that glass like surface and builds the emulsion up off of the threads that cause the interference. Think of how smooth CAP films looks and prints. You get great image quality from cap film.
The best thickness is not measured by the number of coast, but how thin you apply each coat. Someone can coat a 150 mesh 1:1 round edge on the coater and get enough....because they coat very slow and even. Others who coat fast may need 3 coats to get the same thickness.
I've heard/read people say that the one hit white is a myth, A unicorn. I've seen some unicorns. You just have to apply what the emulsion and mesh people actually suggest.
Tony, I'm sure your shop has smooth surface screens. Do you face coat?
Stitches, There are even thicker. 800 and higher I believe. Depends on what you're trying to do.
Remember the guy that enters the special affect category from Istanbul Turkey and another from Egypt at the ISS shows? They are using that fat film and CAP film. They print very slow production for that stuff and often just for show! They print, flash, print, then the 2nd layer art is adjusted to accommodate the stack (cutting the art in thinner). This is what you do when printing a puff down first, then sim process art over top of the puff. The sim process art has to overlap and accommodate for the expansion of the puff and not peak out on the sides.
For me, some of the screens this customer had coated heavy may be a little too much...unless I would be doing special affect inks. The middle image has Metallic gold shimmer in it that was not cleaned out yet.
One of our guys (our members here) posted a puff print last week. It was puffed, but not stacked high puff. I asked how many coats. He said (one). Not one and one, but just one. Now, you can achieve that because as long as you coat slow, you can push it through to the other side to get that glistening affect and it be thick enough. I wouldn't run 5000 shirts on it, but you can do pretty well. In his case, he was just testing. Now, had he coated multiple coats, like that, he could get a puff that can reach a full 1/16" off the shirt. It would blow out and become rocky in texture, but it's really high and works for different effects.
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I forgot to mention, the art that these images show, were indexed at a semi low resolution and textured/distress edged art. Meaning, it had rough edges to begin with so it's not (as clean and crisp) on the edges as you might normally get form such a thick stencil. The one that looks like a#8 or & in it, would have looked very hard and sharp had it been clean vector art.
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2 over 2 stretch and glue...........one hit white with Rutland DC White Plus
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Good post Dan-O, I've play around with doing thick film's and even coating extra thick screens and the problem which I faced was getting a nice one hit white my top colors suffered from me printing with to much pressure causing misprints, but still I think you need a little bit of a gasket on the shirt side of the screen to get a nice ink coverage which I'm sure this guy gets, again good post and read.
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2 over 2 stretch and glue...........one hit white with Rutland DC White Plus
You coat wb/dc screens 2/2? sharp edge I presume?
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yes all screens coated the same way
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I've got some 15s and 17s that I've gone over 1000µ on. Exposure times range from 400 to 600 seconds on a 5k MH bulb. Developing them is a soggy affair for all involved. We usually get them started with the big 3000psi/4gpm pressure washer we destencil with.
Luckily that HD fad came and went and this doesn't come up very often any more. We do 400µ on 24 mesh for glitter studs often though. We use Aquasol HS now instead of fat films. Starting with a 2:2 base coat and then build it up after that dries.
I love this stuff. Great pics.
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Let me ask a question here on coating screen's, I've always coated 2 over 1 which I coat the print side twice and then the squeegee side once, now would it be different and make more sense to coat the print side once and the squeegee side twice which would push the emulsion back to the print side and make a thicker stencil or does it matter.
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I think the end result would be roughly the same. In our testing we found no appreciable difference in EOM regardless of which side you coat more. That final coat on the squeegee side just pushes it all back through the mesh to the print side.
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I think the end result would be roughly the same. In our testing we found no appreciable difference in EOM regardless of which side you coat more. That final coat on the squeegee side just pushes it all back through the mesh to the print side.
Screen Dan, could one therefore assume that you could coat from either side of the screen without a difference? i.e, 3/0 v. 2/1
I've been mulling this over a lot lately, if we need to be flipping screen to coat or if we need to have an auto coater with dual troughs. It seems like the answer is no if using thin thread mesh but old habits die hard.
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Here's a 400 micron stencil from a job we printed yesterday. We use this to create a raised puck effect.
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I think the end result would be roughly the same. In our testing we found no appreciable difference in EOM regardless of which side you coat more. That final coat on the squeegee side just pushes it all back through the mesh to the print side.
Screen Dan, could one therefore assume that you could coat from either side of the screen without a difference? i.e, 3/0 v. 2/1
I've been mulling this over a lot lately, if we need to be flipping screen to coat or if we need to have an auto coater with dual troughs. It seems like the answer is no if using thin thread mesh but old habits die hard.
In the limited experience I have in coated screens among other things at a small print shop in the last year and a half (before that was usually too busy in large shop art departments to get into much printing)... I wanted to get into the fun side of things for a change, get my hands covered in ink (and emulsion) .... but in just my limited experience and with a lot of not-so-great equipment... at least a stable method for me is 1-over-1 coating, have not tried face-coating or coating more.... dont want to mess too much with the already-weak exposure times... but I have found a definite difference in whether it was coated squeegee-side first then shirt-side, or shirt-side them squeegee-side... the coating is pushing it through to the other side... and then the direction they are layed to dry as well, perhaps even more of an effect. So I prefer and it seems between me and the other guy that it does work best to have a thicker EOM on the shirt-side, and we achieve this with 1-over-1 coating using rounded edge of the scoop and coating shirt-side to push to the squeegee side, and then squeegee side to push it thicker back on the shirt-side, and then laying to dry in the rack shirt-side down so gravity pulls an even layer that is thicker on the shirt-side. At least from my limited experience with these things I can tell it affects the prints and we don't usually run anything near high-volume numbers, just a manual and small runs, so no breakdown issues really even though the emulsion is pretty thin on the squeegee side. But I haven't pushed for trying any extra coatings yet, so I don't know.. at least with 1 over 1 and the technique for which side you do and which way it lays to dry, seems to have the effect I want which helps a more even print and more ink get through on the shirt -- and also because of wash-out mostly from the shirt-side (weak exposure times and can blow-out emulsion from the squeegee side - because its not as mush mesh its adhered to as well there)... but the compromise I at least want on the shirt-side to give me more ink etc.... I can see usually and tell just looking at them where you see if waves of emulsion or uneven coating and drying caused it to be thicker on one side or the other in non-uniform ways, I try for the shirt-side thicker, but I am replying to this and interested in this discussion, been reading it and also want to understand maybe would the drying-direction affect extra coats? Or would coating and drying like doing the 1-over-1 and shirt-side down, then coating again later on the squeegee-side, that should add more there, another coat on the shirt-side would thicken that side.. but then if there is dried emulsion between them does the drying-direction matter then? Or if you coat 3 over 3 and lay face-down there is a thick layer of emulsion maybe gravity pulls it and has the larger affect over the drying time, so you could coat 6 times on one side, and lay it the opposite direction and it dries thicker on the side that gravity pulls it toward? I'm not familiar with other ways of drying screens after coating besides laying them level. Great thread, I'm just a printing novice but learning something new every day just like on the art side.
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I think the end result would be roughly the same. In our testing we found no appreciable difference in EOM regardless of which side you coat more. That final coat on the squeegee side just pushes it all back through the mesh to the print side.
Screen Dan, could one therefore assume that you could coat from either side of the screen without a difference? i.e, 3/0 v. 2/1
I've been mulling this over a lot lately, if we need to be flipping screen to coat or if we need to have an auto coater with dual troughs. It seems like the answer is no if using thin thread mesh but old habits die hard.
I think that would be a fair assumption...but for some reason I can't bring myself to coat only one side of the screen.
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2/2 was my method for always, with a full coater, 2 on the print side, 2 on the squeegee side, up to 3 and 4 on the squeegee side as the coater had less in it, because I was trying to get the same "glisten" look as when the coater was full. This could be adjusted depending on the mesh too. And, sharp edge only, purely a personal preference. And it needs to be said, I don't make screens anymore, we have a full time guy for that.
Steve