multicolor wow discharge

[JBLUE]

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.

[tonypep]

Hardener on the bottom only and never mist the screen

[ZooCity]

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.

[Admiral]

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. 

[ZooCity]

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. 

[RICK STEFANICK]

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.

[tonypep]

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

[Itsa Little CrOoked]

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.

[ericheartsu]

Correct, we notice it most on the auto, but we don't really do that much multi colored discharge printing on the manual

[Itsa Little CrOoked]

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.

[ericheartsu]

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!

[ZooCity]

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.

[Itsa Little CrOoked]

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.

[ericheartsu]

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?

[tonypep]

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!