Discharge vs Plastisol Vibrancy (CCI)

[tonypep]

I mentioned last week that Rutland came by to do some testing and we found their DC white out performed the Sericol and CCI. It is slightly bluer which gives it a more optical white appearance. (An old trick they probably borrowed from their plastisol formulas). They are working on a new one.

[ScreenPrinter123]

Good to know about the Rutland, will give it a go once we finish our D-White.  Well I wish I had great news for our first discharge run (and a fairly long run at 600+) but I knew better than that!

Started of great with the white and teal coming out better than I was expecting on a purple shirt...then the screen failure started.  Here is what I think happened and if you have any suggestions I am all ears:


1) First set of screens were underexposed (still figuring out the WR-25) with hardener that was most likely not allowed to dry all the way.  Taped some pinholes on the print side of the screen and after about 200 shirts started getting a white line (after running through the dryer) wherever the edges of the tape were on the teal screen.  This really had us baffled since it was showing white on the teal screen.  My best guess is that either the hardener or ink was causing the tape to breakdown and cause this (White #500 from JandJ) or the discharge base was seeping to the edge of the tape (not sure why the base but not the pigment would seep). 

The emulsion became real gummy and the tape would not adhere well and would slide around fairly easily so we bumped up our ltu for round two.

2) On the second set of screens did not want to wait for hardener to dry and thought the underexposure was the main culprit (mistake) and pinholes started appearing after roughly 100 shirts.  Possibly still and undexposure problem though there was no gumminess during washout.

What kind of runs are you guys getting with WR-25 with and without hardener.  This will help me know if undexposure is the likely culprit.  It is just hard to go from 13 ltu with Chromablue to 110 ltu with the WR-25 and have the screens break down so quickly but if I must wait longer for proper exposure than so be it.

I appreciate the help...now its time to order way too many replacement shirts!!!

[brandon]

Hey Guys,
Are you using reg marks and just taping over them? Uh oh if so. If/when we use reg marks with water base before they hit press we apply block out over them, allow to dry, then apply hardener for jobs over a couple hundred or color changes just to be cautious. We also use a different emulsion but I'm sure the one you have is fine. But the water base will go through the reg marks and around the tape if not

[Screened Gear]

Under expose on press can be fixed with exposing your screen after the stencil is washed out. Taping is important. I have got the tape lines on my first run of shirts. You have to keep the ink from working it way under the tape. I tape my reg marks and then add rows of take like shingles on a roof so the print stroke starts on tape. If the squeegee runs over tape it will work ink under it after about 50 shirts. No matter what tape you use.

[Screened Gear]

Hey Guys,
Are you using reg marks and just taping over them? Uh oh if so. If/when we use reg marks with water base before they hit press we apply block out over them, allow to dry, then apply hardener for jobs over a couple hundred or color changes just to be cautious. We also use a different emulsion but I'm sure the one you have is fine. But the water base will go through the reg marks and around the tape if not

What block out are you using? I have only seen waterbase block outs.

[ScreenPrinter123]

Thanks for the suggestions, will heed the advice.  We did post expose the screens for the same time we exposed them so I would love to hear how many prints WR-25 users get with discharge/WB without hardener to give us some sort of benchmark

I will get some fast drying nail polish to use as blockout instead of taping the reg marks on the print side of the screen as I remember reading that in another post.  Looking forward to solving these initial hiccups as I can already see why you guys printing discharge and waterbase on a regular basis seem to prefer it to plastisol.  It prints faster, easier, and is cheaper to boot...unless of course you screw up a bunch of shirts!

[brandon]

Hey Guys,
Are you using reg marks and just taping over them? Uh oh if so. If/when we use reg marks with water base before they hit press we apply block out over them, allow to dry, then apply hardener for jobs over a couple hundred or color changes just to be cautious. We also use a different emulsion but I'm sure the one you have is fine. But the water base will go through the reg marks and around the tape if not

What block out are you using? I have only seen waterbase block outs.

On the block out / tape up screen station we have a super small container of our emulsion that we apply with a plastic card. So once the screen is completely dry we cover any reg marks if needed for water base. Wait to dry. Then apply hardener if needed as well. Once completely dry again apply tape. Been doing it for years. No problems.

[ebscreen]

No tape on bottom of WB screens ever.

We put reg marks far enough above and below the art to be able to shorten the stroke
and not print them. We also tape over them on the ink side just in case (ink starts flingin)

We use Aquasol HV which as a photopolymer technically shouldn't be as durable, but we don't
use hardener on anything less than 100 pieces or so, and never have any problems. Hardener
on 10K+ plus pieces and no problems either.

Best advice, two things actually, don't rush the pre-press. Take your time exposing and drying and
blocking out etc.

Second, hard sharp squeegees and lots of pressure are pretty rough on your emulsion.

[brandon]

Yeah, we use Aquasol HV as well. Come to think of it in regards to our water base jobs I just realized I don't know why we have been using tape on that side of the screen. We have everything blocked out if there are reg marks and good to go. Just a hold over from plastisol. Damn, years of tape wasted. Ugh!!!

[ScreenPrinter123]

Good call on the stiff squeegees as it didn't even cross my mind (though it should have).  Need to get some new ones as our current inventory was purchased when we discharge was not even on the radar.

Would a 2/1 coat offer any advantage over a 1/1?  I wonder with proper pre-press if there is anything to be gained by a slightly thicker stencil.

[ScreenPrinter123]

This is Brian -

I'm not sold on the wr25 since there's supposedly a w14(?) that's supposed to have all of the Benefits of wr25 but a much shorter exposure time. Any testers got pro and con feedback?  We may give the aquisol a go.

So for pressure and squeegee what are you guys using - 60 duros?  40psi?  We were at 45-48 psi with 75/95/75s change the blade and/or less pressure?  We kept hearing smash that ink in for good saturation so smash it we did - with plastisols we are anywhere between 15psi-35 psi.

[JBLUE]

Under expose on press can be fixed with exposing your screen after the stencil is washed out. Taping is important. I have got the tape lines on my first run of shirts. You have to keep the ink from working it way under the tape. I tape my reg marks and then add rows of take like shingles on a roof so the print stroke starts on tape. If the squeegee runs over tape it will work ink under it after about 50 shirts. No matter what tape you use.

Jon I have to disagree. I have been told by both Kiwo and Murikami this is not the case. If you do not nail the exposure the first time your in for problems. I would have to agree with them. We were under exposing and post exposing with nothing but  problems. Once I nailed the exposure there was no need to post expose again. On long runs we use diazzo and hardener. Screens hold up for as long as we run now.

[Inkworks]

We only post expose because we are blocking out with emulsion and want to harden that.

[Screened Gear]

Under expose on press can be fixed with exposing your screen after the stencil is washed out. Taping is important. I have got the tape lines on my first run of shirts. You have to keep the ink from working it way under the tape. I tape my reg marks and then add rows of take like shingles on a roof so the print stroke starts on tape. If the squeegee runs over tape it will work ink under it after about 50 shirts. No matter what tape you use.

Jon I have to disagree. I have been told by both Kiwo and Murikami this is not the case. If you do not nail the exposure the first time your in for problems. I would have to agree with them. We were under exposing and post exposing with nothing but  problems. Once I nailed the exposure there was no need to post expose again. On long runs we use diazzo and hardener. Screens hold up for as long as we run now.

So your saying the post exposure does not harden the emulation as well as the first exposure. I could agree with that only because of one reason. If you under expose the first time you would wash off emulsion that was needed, like pin holes, and emulsion thickness, then the pose exposure can't help. But for break down of the emulation on press should be able to be fixed wth post exposure. I do agree a good exposure is key.

[ZooCity]

That's a bummer w. the screen breakdown.  Print looks good though.

70 or 60/90/60 to prevent the blade contributing to breakdown.  You'll get a deeper bend, creating a sort of ink tunnel that will help drive the wb into the fabric.  Couple of things you can do:

• Round the squeegee corners.
• Apply emulsion after exposure to beef up the squeegee edges and the start/stop for the blades.

And of course, full exposures.  In the middle of 800pcs right now and not expecting a breakdown.  Aquasol HV + Murakami hardener MS but any good emulsion suitable for wb will get you there.

I use emulsion to blockout any reg marks, fisheyes, pin holes, etc. so that's reason 1 to post expose but I still think it doesn't hurt to hit your long run screens with 2-3x the original expo time on the squeegee side.  I won't hear an argument that this does nothing.  Back in the early days I would develop sometimes underexposed screens (using sunlight) gently dry and post expose from the squeegee side and it worked with diazo emulsions so it definitely is doing something to those pure photopolymers which are noted for being able to further cross link in post exposure.  Not a substitute for complete exposure though.