W.O.W. WB Discharge--Picks up on underside, skins over, and fouls my images...

[Itsa Little CrOoked]

I tried to get it all in the subject line, but to clarify:  I run a manual shop. I like WB discharge printing more and more, but on multi-color Wet On Wet runs over 60-80 pieces or so, plates 2, 3, 4 etc, pick up enough ink to cause problems. The ink "skins over" to a thick enough matrix to re-apply to my image area as visible "flecks" of half-dried ink. It is worse in hot weather of course.

I actually posted this on another forum over a year ago, and to this day, I still don't have a clue how to solve it. I call it Zombie Skin because if I don't print some sacrificial paper to partially clear the underside of the stencils from time to time, thats what it reminds me of.... Zombie Skin from a "B" movie.

Someone mentioned Silicone Spray under to plates to keep it from happening, but it just seems counter-intuitive. I used to run a sign shop and silicone and paint mix like oil and water.  I guess I'm just not willing to try silicone around my WB inks unless someone I trust says so.

I am really wanting to succeed at this, BEFORE I make the jump to an auto.

Stan

[brandon]

There is a lot to go over here and I have to split in a second but if you have any white discharge pigment in the mix you are going to have some buildup with wow printing. Whenever we do any wow discharge/water base white goes last!

[JBLUE]

Speed up. Your printing to slow. Seriously. We run into this when we stop and the back sides of the screens start to get tacky because they are drying on the underside. Thats why once you start running make your stops as minimal as possible. If you have to stop try misting a little bit of water on the backs. Those crumbs do not affect it much through the dryer.

[ericheartsu]

Also are you using White in any of these WB/D ink? we found that that was a huge culprit for us

[Itsa Little CrOoked]

Sorry for the slow response, I was on the road this evening. And oh yes, white goes down last in our shop, when we discharge. Printing white last does help, but only with that one aspect.

I know speed is important, but even going pretty hard, I have problems out past 50 pcs or so....with multi colored W.O.W. jobs. Typically on a 4 spot-color job with large solid areas, I'll load 1 (one) shirt on 1 (one) platen, and print all the colors on that one shirt.... starting with the smallest block of color first, moving to the larger design elements, then ending always with white. (CCI D-white is my favorite) I mist the flooded ink with water frequently, especially white, if any, and then I mix the water into the thirsty ink over the "inkwell" with my squeegee blade.

HOWEVER I HAVE NEVER TRIED MISTING THE UNDERSIDE of my stencils. It seems to me likely to spoil the next shirt with diluted ZFS. I've done that just with over-misting the backflood.

Once the referrenced problem with drying ink develops, I print paper, which helps (barely) but not for very long....  I rarely have the actual image area "dry-in" on any particular stencil, unless it has tiny halftone dots.

What works better, if anything...than printing on paper to clear the mess??? Can you clear the image area by printing on paper (or pellons) and dry wipe the remaining residue from the underside of the stencil??  I've actually done that a time or two, but the image area gets too dry if I'm not EXTREMELY careful.

I need an auto I guess, but not right now.

Stan

[brandon]

Exactly. That was my point from an earlier post. White discharge mixed into pantone colors will have that effect sometimes. Also please remember when you move onto your auto you will have the option of higher mesh counts and printing waaaay faster. A lot of shops we talk to think 230 mesh is the highest you can go with discharge and we hit the 350 mark sometimes. Killer detail. But the higher mesh with one stroke will also help the wow printing. And silicone and water as you mentioned above? Try printing silicone ink on water resistant material! All I can say is

n i g h t m a r e

[brandon]

And I also just realized any discharge job at our shop over one color and over 72 pieces goes auto, no manual. Nothing against our manual guys as they kill water base but dcharge is a different beast

[Itsa Little CrOoked]

@ Brandon, I meant pure silicone spray on the underside of the plate, not silicone ink. Yikes!!

Somebody wrote, or told me.... I forget which.....that they spray silicone on the underside of their stencils to control ink pickup with discharge printing. (I just doubt that.....)

[brandon]

@ Brandon, I meant pure silicone spray on the underside of the plate, not silicone ink. Yikes!!

Somebody wrote, or told me.... I forget which.....that they spray silicone on the underside of their stencils to control ink pickup with discharge printing. (I just doubt that.....)

That might be true, I am not sure. I do know with our wow plastisol printing it is not an issue with correct inks and mesh tension. Tension falls or low bleed inks you have a problem. No point for the silicone spray and according to all of our plastisol reps that stuff has not been needed in ages. But I assume as our problems/situations go away with discharge / water base / plastisol wow printing I am going to say it is all the same as above - correct ink usage with the correct mesh and tension. That does not mean I am right though, just what works for our shop

[Itsa Little CrOoked]

I DO like higher mesh counts on plastisol, but 305 is my max, being I am a manual shop. DotToneDan sepped a 6 color WB discharge SIMULATED PROCESS(!) job for me a while back that came out nicely. I printed all the colors through 305, which I previously thought was impossible on a manual. WRONGO!!

You know, now that I think of it.... I don't remember the "Zombie Skin" on that 120 piece job. Maybe I just forgot. It WAS cooler weather though. Dunno.....

[screenprintguy]

we changed from Matsui discharge base and whites to CCI and we no longer have that problem

[Itsa Little CrOoked]

Screenprintguy, I assume you mean Discharge bases, although the problem seems about the same with straight waterbased inks on light shirts to me.
 

I've not used the CCI Bases.  Do the Matsui PC Pigments seem compatible with them?  Do you use additives, say Printgen MG, or Fixer N?

I'd really like to know the specifics from anyone who has managed this problem successfully. I am not expecting moving to an Auto anytime in the next few months.

Stan

[screenprintguy]

I still use the printgen and the fixer to lock in the colors, just switched to cci for discharge base and discharge white. Anytime we had an issue with straight wb caking up was from either alot of air flow near the press drying the wet on wet ink on the back of the screens, or the heat from the flash on the boards causing the wb ink to dehydrate. we no longer run our flash with wet on wet wb and or discharges and have had no problems. the Matsui discharge base would cake up after 100 or so wet on wet prints and now with cci not only do we not have that issue, but the discharge is deeper in the fabric, colors are more true and it seems to cure quicker in the dryer vs the matsui. We still use the matsui pigments and activator works with the cci no issues as well.

[Itsa Little CrOoked]

That is exactly what I was looking for, THANKS!  I'm going to order both CCI Bases and give it a try. 

I guess I do have a couple of quart samples of the CCI D-bases here...one is marked "Regular" and the second one must be the "Premium" but it isn't marked. That might be just enough to do the job I need to run by Friday. 

Screenprintguy, how much Printgen MG and Fixer N do you add to your CCI D-Bases? With Matsui, I never exceed 3% of the Fixer N, but I have at times doubled that percentage of the Printgen MG....to maximize the wetting agent effect.

[JBLUE]

That is exactly what I was looking for, THANKS!  I'm going to order both CCI Bases and give it a try. 

I guess I do have a couple of quart samples of the CCI D-bases here...one is marked "Regular" and the second one must be the "Premium" but it isn't marked. That might be just enough to do the job I need to run by Friday. 

Screenprintguy, how much Printgen MG and Fixer N do you add to your CCI D-Bases? With Matsui, I never exceed 3% of the Fixer N, but I have at times doubled that percentage of the Printgen MG....to maximize the wetting agent effect.

You dont need Fixer for the white or base FYI.