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screen printing => Waterbase and Discharge => Topic started by: ericheartsu on February 07, 2013, 11:04:54 AM
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Is there a trick to avoiding the zombie skin on a WOW discharge print?
Right now we are printing a three color print on an Anvil 980 (blue, red, white, in that order), and the only thing we can do to avoid the zombie skin forming, is by flashing each color, which in my opinion defeats part of the purpose of discharge ink.
So any tips? our off contact is pretty standard, all meshes are around 40n (36-40) at least, and all three prints are being done on 160 mesh.
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We never ever ever flash DC and do it all day long. Can you give specs so we can chime in with some help? I've never experienced what you are describing.
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in the past we've used matsui white, and sericol colors. We just changed to CCI dwhite.
But what seems to happen is, printing wet on wet, the colors start sticking to the screen of the next color, and eventually form a weird skin, that gets pulled off on the shirt, and can cause slight discoloration where the design is
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in the past we've used matsui white, and sericol colors. We just changed to CCI dwhite.
But what seems to happen is, printing wet on wet, the colors start sticking to the screen of the next color, and eventually form a weird skin, that gets pulled off on the shirt, and can cause slight discoloration where the design is
we are in the same boat, we used to use matsui HO white, I believe, and I have my first gallon of CCI here. We found it was underexposed screens causing most of this issue...is it like flaking off onto the shirt as well? not really an orange peel but a really funky texture?
I think adding a bit of retarder or water helped as well, I have to go check my notebook. I keep notes on everything
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Hmm well make sure you are post exposing then. Also what brand. Matsui is OK but I don't have any of it here. Trying to eliminate the variables. Squeegee parameters?
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homer, that's exactly whats happening, almost like a weird gummy residue.
We have changed our system a little bit too, since it happened last, but we are doing another job soon, So i wanted to check and see if there was something we could do.
I'll try post exposing for longer, and report back!
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Been doing it for more than 25 ys and have never seen this. Somethings afoot!
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I would grab some of that CCI hardener and put it on the screens, that way if you are still underexposed, you should be safe...er....what emulsion are you using? We are using aquasol hvp and currently trying the CCI TX-Discharge, pretty much the same stuff....
now that I think about, when this happened to us last, we had our screens coated for plastisol, not discharge so we may have been putting down too much ink...
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I've had this happen too. Happened while using Aquasol HVP w/ hardener. Only happened after we had been running for a while and stopped to make some adjustments - seemed to be the ink on the back of the screens not staying wet? Now that Homer mentioned it maybe too much ink lay down too.
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what is the appropriate way to coat the discharge screens?
we are using kiwo discharge emulsion, and when we hvae 100+ runs we typically throw the CCI semi hardner on the screen
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We do 2 over two sharp side and post expose. 70 Duro sharp sqg. Remember your driving it in not laying it on
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for us it's 1/1, we want the WB ink IN the shirt, not ON the shirt, like you would with plastisol....so a thinner stencil...
maybe some of the WB guys can chime in here but that is my understanding.
oop, looks like TP beat me....
I thought I read on here post exposing was really only for hardening the emulsion used for blockout?
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You want them screens dry and hard. The dryer and harder the better in terms of water resistance
and not degrading. (not so much in terms of reclaiming)
Can't wait until the sun comes out and we can post-expose for free and easy again.
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Lol, Zombie Skin, good to know it has a name...
I've found misting the backside of the screens with a bit of water prior to running helps. Maybe the emulsion absorbs a bit of water from the ink and dries it out enough to cause it to skin and then release onto subsequent prints?
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Are you guys putting hardener on the bottoms of the screens as well? I've never had issues if I put hardener on both sides.
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I run hardener on both sides. Its overkill but still cheaper than replacing 24 shirts. By the time its at the end of the dryer to the screen that has the problem is about how that works out to. So we just go the better safe than sorry route. We also dont stop in the runs if at all possible. We only see that when we stop and the ink on the back sides of the screens dry out a bit. It leaves a few chunks on the next few shirts and then is gone.
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Hardener on the bottom only and never mist the screen
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I've had DC build up on multicolor runs but never the "zombie skin".
#1 thing was already mentioned- super dry screens with hardener. The hardener really helps keep the underside of a screen from getting too wet. I don't know how/why but it does. Very noticeable when printing paper but we tend to overlook it with shirts. You'll see unhardened WB screens picking up all manner of lint from Ts on even a one color run if you stop and look. I harden both sides and than blast out the image areas with clean air. You only need to do the backside???
#2 is keep it moving, fast as you can go. I only have seen the backside of screens skin up a little when I stop. Even though you flood the top of the screen to prevent dry in, your WOW build up on the backside is just hanging out and getting dry.
I think this thing is a combo of half dried/half wet WOW buildup + sticky wet backside of screen making a gummy mess.
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Screens could be too high tension. You want to drive the ink into the shirt and maybe that is why consecutive screens are picking up too much ink and having this weird issue.
Are you using a dual cure emulsion? why not try a diazo instead if you are? I like using sp-1400, never had pinhole issues in the run or break down. Don't have to post exposure, have to expose properly the first time. Pure diazo emulsion doesn't really benefit from post exposure.
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Here's something- try printing on contact.
The ideal is probably ultra ultra low contact (which would mean ultra, ultra high tension and pressure) but just give the no o.c. a shot and see what happens. Peel issues are significantly lessened with WB.
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We do 2 over two sharp side and post expose. 70 Duro sharp sqg. Remember your driving it in not laying it on
remember when post exposing. 10 minutes is the equivelent of 1 minute the first time.
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In all my articles on discharge and WB I have tried to communicate that while discharge printing is actually quite easy it is different. One of the primary reasons it has taken so long to finally catch on is that so many of the theories and practices that have been preached and drilled into us by the Gurus need to be reconsidered (That made a lot of them crazy). The companies who made or distributed the inks truly didn't/don't really know practical application. The fact is that we cannot ignore the interdependant variables that apply to what we do. Switch one and some of the others must change.
Thats the great thing about this forum and why I believe it to be far more valuable than the trade mags. This is practical advise coming from real people from all over who are sharing what works for them and perhaps more importantly, what doesn't
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I am a manual shop, and I was HOPING this just HAS to be less of a problem on an auto--which is hopefully in my near future. I've started 2 or 3 threads about this issue on theshirtboard and other forums over the last couple of years. In fact I'm pretty sure I coined the term Zombie Skin as applies to our craft, I was having such a time with it. I haven't found a solution yet, but I've had several responses.
I thought about prepping the screens before printing with Silicone Spray on the shirt side, but I was raised in a Sign Shop and Silly Spray wasn't allowed anywhere close to paint, or painted surfaces. It just seems like a bad idea.
It makes sense that a VIGORUS post-exposure would help, but I can't really say it did. Hardener on the platen side of the stencil really didn't do much of anything either...at least for me.
Like I said, I've fought this a long time, and so I've thought about it a long time too. I now believe it is simply the drying (skinning over) of the transferred ink deposit, and there is no solution for it on a manual. When it happens, I just clean it off with DRY paper towels, and re-flood. Then I move on to the next screen and repeat. WOW is gonna pick-up, and that picked up WB ink is gonna partially air dry. Period. On an auto, the "ACTION" continues apace...so there is much MUCH less time to develop Zombie Skin, due that physical "stirring" action of the ink deposit caused by the squeegees and shirts.
I should have asked, Ericheartsu is this problem on an auto? If so, that lends credibility to an undercured stencil theory contributing to the problem.
Stan
P.S. I am NOT an expert in printing anything, much less Discharge and Waterbased. So take a grain or two of salt, My Opinions Are My Own, YMMV...all that stuff.
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Correct, we notice it most on the auto, but we don't really do that much multi colored discharge printing on the manual
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Correct, we notice it most on the auto, but we don't really do that much multi colored discharge printing on the manual
You know, that does raise the question of stencil prep all over again. VERY interesting... It runs against my understanding of the issue. (Not the first time. HA!)
Well, like Tony, I use CCI WR25 emulsion, 2 over 2 with the sharp edge. I do WB and Discharge WB ON contact. But my light source is just fair--a Nu-Arc 2125 with an aging HID bulb. It works, and I believe I have it dialed-in. I am currently not post-exposing, but I sure can start again. And I might go back to adding hardener on the underside again.
The fact that you are experiencing WOW Zombie Skin on your auto, gives me pause...and a little hope actually. Perhaps we can pin this down.
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I agree with you and Tony about narrowing down all the different factors. The truth is, we've since switched how we've been making our screens, and the thought to post this, happened as we did our first multi colored discharge job this year. I'm going to do some tests in the next week or so and see if i can pin this down too!
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Homer mentioned running plastisol coated, therefore I would presume thicker, screens with DC and having the issue. Using a stencil built to pump ink on the top of a substrate would definitely leave more up top to pick up.
Toss in the fact that a thicker coat = smoother to downright glassy stencil on the shirt side. Now you are dealing with too much ink to start and the next screen coming down has a surface that is ideal for picking up material since there is nothing to break up the surface tension.
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Zoo, I absolutely agree that more ink laid on TOP, translates to more ink picked up by the next screen. I've seen that happen. But I'm not entirely convinced that less ink transferred to subsequent plates makes much of a difference with Zombie Skin. It may help, or it may not.
You know how with a WOW plastisol job, eventually the ink picked-up about equals the amount of ink laid back down? I think so, anyhow.... Well, if the WOW WB job in question would do a similar thing, MORE transferred ink might actually keep things moist and fluid. I'm just talking crazy here, I know, but I have this whole barnyard physics thing going on in my head, and it needs some guided observation to dot all the i's and cross all the t's. I'm all ears on this one. Been fighting it for 2 full years!
With the whole Zombie Skin thing happening on a auto, (which surprised me...) I don't personally think the amount of ink picked up is likely to be a significant factor. It seems more like some of the ink's moisture soaking up into the emulsion exaggerating the drying problem, or something similar.
The fact that Tony is not experiencing this phenomenon on autos, and ericheartsu IS, makes me think I've been on the wrong track.
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Doing a multi color discharge run on the manual today, and will report my results when i can. Here is the information so far:
I'll be printing a red and white print on a Gildan 64000 Tee, using a 160 mesh screen, at 30n. I'm using CCI White Discharge, and Sericol Red Discharge. My screens were exposed last night, and have dried overnight. They were coated 2/1 with Kiwo discharge emulsion, using the sharp edge. They will be post exposed for 140 lumens on each side of the screen.
what is the appropriate off contact for a job like this? Tony, i believe you said that we should not be saturating the ink into the shirt, but rather laying it on top, so it would require less of an ink deposit is this correct?
Also for a job like this we'd typically use a 60 duro squeegee. Is the appropriate squeegee that we should be using? I've been afraid to sharpen my discharge squeegees, for fear of the sharper edge not printing as well, but i also feel this issue will come up with a duller blade. Any tips on that?
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30n is overkill for discharge but probably not a problem. Add a titch of water to your inks. We use 70 duro for most prints. Sharp like new blades. You don't want the ink to sit on top but drive 1/2 to 3/4 in.
Good luck and post pics!
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The imprint is a very large white print, with a small red print in the corner. What order would you set the screens up in?
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And what do you guys think the appropriate off contact should be for this?
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Red then white. I sometimes have to double stroke a first down color to keep it vibrant after the other colors go down, but that's typically only needed on four colors and up.
I know it's not the goal here, but a quick flash on the red could be used if wow gets problematic.
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Oh and I go on contact
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Red then white. I sometimes have to double stroke a first down color to keep it vibrant after the other colors go down, but that's typically only needed on four colors and up.
I know it's not the goal here, but a quick flash on the red could be used if wow gets problematic.
we typically flash between the colors, to make sure they stay vibrent, but i'm trying to avoid this, for this particular job!
but i'm also trying to learn from this experiment, by getting you guys to give me your advice!
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Flashing btwn colors will begin to cook and gel the inks watch out for Zombies! Seriously we never ever do this.
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Flashing btwn colors will begin to cook and gel the inks watch out for Zombies! Seriously we never ever do this.
so weird, it's the only way we get around the zombie skin!
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Don't know! We printed (8) 2 sided jobs already without stopping once to do anything this morning. Its SAP for them. And use different bases and whites sometimes need to use whats at hand.
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Yup, just printed a six color wow discharge no flashing. 900 pieces. Darkest ink to lightest on this job. White last as always. Looks awesome!
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2600 red/white coming up now f/b. Suspecting high tension and off contact issues. As said above we're about 15n almost no off contact. This used to make the gurus Bat crap Crazy when I told them no Roller Frames for me thanx. Matter of fact I've got a crap ton for sale 23x 35 all meshed and clean.
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And here is the front after 1,000 hits no stops.
Hint: always print reds last for maximum pow!
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That looks like plastisol to me Tony. Is that a base white peeking out from under the red?
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My apologies and good catch! I just ran out and checked and its a DCUB! And good thing probably because it's on Canvass goods. But the red last comment is a little known fact BTW. I'll post one of those when we get to one.
This photo does not apply!
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So if you are printing red and white discharge Tony you print the red last?
We always print white last, even in that situation. Oddly enough we're doing it
right now and the red imprint is much larger than the white, probably should
have reversed it.
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Yes we do. Not flashing but a slight steaming. All of our whites have base in them so pickup almost never happens. No one knows why the reds print bolderlast. I discovered this by accident. Not sure if a customer would notice though. You'll see it side by side comparrison
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We;ve always found printing white last gets the brightest result for whites at least.
OK update on this. So we ran the job, not a single problem. I really think you guys helped me figure out the screen coating and post exposures really aided in fixing this problem. I'm trying to take pics right now
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Awesome.
I should qualify my flashing statement- we have never ran a flash on a wb/dc job and we run up to 6 colors. I just see where a "half" flash, just enough to move a little water out, in the middle of, say, a 6 co run is a quick and easy fix and would increase print quality and maybe even save a little ink by preventing the need to 2x stroke the first color(s) down.
Plastisol tends to squish around and we all have to fight that build up with various approaches but when using it but WB is so different in that you are dealing with the suction of a soaking wet ink layer and sometimes getting just a titch of that water out of there makes an immense difference.
Heck, to achieve this effect you could probably just run a plain old fan in one head, like a cool down, so long as you could buffer it to keep from drying out adjacent screens. No heat then and not much more in energy costs but it does eat up a head.
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How do you guys keep your pallets tacky with no flash? We'll flash 1-2 sec or so even if we don't need it
just to keep the boards sticky.
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I do extra tack (TexTac, rolled on with a "hot dog" foam roller) on the image area and flash the platens after applying but not during printing. First two shirts are damn near glued on but it holds up for a good while.
I like the put a gap on the belt between sizes so I'll typically stop and mist/scrub/reapply tack and let them dry while I go grab and stack shirts or put more ink in the screen or have a smoke or whatever. I get nervous about the wb tack and wb inks.
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I'm near the end of a big run, 3 color back, 4 color front all waterbase no flash
I'm getting build up though mostly on the last screen, after 500 or so shirts I need to wipe a couple screens.
This isn't discharge since it's on natural color shirts, using all 150S mesh.
Any advice?
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I haven't done a largish discharge (or straight wb) multi-color W.O.W. for a while, with large areas of spot color. That's when I have.a problem.
But the next job that fits the scenario, I'ma post-exposing that sucker in a serious kind of way, and then I'll use some hardener. I've got to rule out any possible link to the stencil. Rule it out, or possibly nail down the cause. I posted the Zombie Skin problem on another forum 2 years ago, and didn't find a suitable solution.
Maybe I'm just dense....