More Screenprinting

• May 2nd, 2006 • • experiments, how-to, screen printing •

Screenprinting has been helping me to satiate my printmaking fix; it’s been almost two years since I’ve touched an etching press! Fortunately silkscreening is horribly cheap and easy, and doesn’t require a whole lot of space. I’m sure some of the hardcore old dudes would cringe at my self-taught techniques, but hey, when you’re broke some of ‘em look pretty good!

I figured I would share some of the troubleshooting I’ve gone through (most of it last night) in hopes of some feedback or benefitting others. Back when I was messing around with a lithography press, I made a horrible mistake. See, when you’re working with a stone, you make parts of the stone hydrophilic and other parts oleophilic. Because I was new to litho, my stone wasn’t quite set up right: it was absorbing some ink in areas it shouldn’t have, and water in others. However, it was still crudely workable. My Big Mistake(tm) came when it came to running the stone through the press. When litho stones go through a press, they have a sheet of plexiglas or metal on top, covered with a line of grease to help it squeeze through the press at tremendous pressure. Whoops, dopy me, I ran a newsprint proof through with the plexiglas upside down. This means that the sensitive stone ran through the press at high pressure just SUCKING grease in. I panicked of course, but my prof came by and ran emergency stone resuscitation procedure and fixed my unfixable problem. Point of my long drawn-out story is, “It can be fixed!”

So! A buddy of mine called me up in a panic about her screen which wouldn’t let go of some diazo photo emulsion on a nylon screen. She hadn’t left it out or overdeveloped (as near as we could figure it was either mixed wrong, or a bad batch) but the emulsion stuck fast despite her using an entire bottle of diazo solvent. Hmm.

Analysis: How bad was the damage?
I’m not sure I would’ve attempted this on an ENTIRE screen but my buddy’s screen only had a few stubborn spots. I figured this was workable. We both agreed to try an all out assault at the risk of ruining the screen, seeing as how it was ruined with the perma-spots anyway.

Trial 1: Bleach
We poured straight household bleach into a tub and tossed the screen in to soak for 10 minutes. The emulsion broke up and released a little bit after some coaxing with a toothbrush. The bleach method was repeated two more times, with some success, but largely the spots stayed.

Trial 2: Mr. Clean Magic Eraser
If you don’t own one of these, get one. They’re delightfully non-toxic, require no chemicals and are surprisingly effective at getting dirt/grime/whatever out of tiny areas. We made sure to rinse off ALL of the bleach, as chlorine bleach ruins the “eraser”. Mr. Clean did a pretty darn good job at cleaning out many of the pinholes in the screen! While the eraser didn’t do enough to remove our emulsion spots completely, I definitely will be using it to clean screens in the future.

Trial 3: Acetone
After a VERY THOROUGH RINSING I opted to try alternative solvents. Down in the studio I tentatively brushed acetone onto the trouble spots with an old paint brush. Almost like magic, the emulsion released and dissolved. My concern was dissolving the screen as well, but it didn’t seem bothered. The only problem with the acetone is that it broke the emulsion down into a fine film. I figured that the photo emulsion remover would take this right off.

Trial 4: Photo Emulsion Remover
Nuthin’. Lot of scrubbing and the emulsion film stayed.

Trial 5: Back in the Bleach
SOME spots came clean, most of it stayed though.

Trial 6: More Acetone
Rather than brushing on, I set the screen down so that the actual screen touched a sheet of glass. Then we poured acetone into the middle of the screen so that it pushed any photo emulsion residue outward to the edge of the screen. Worked well! Hooray! I dabbed intermittently with an old rag to work the acetone around.

There you have it, the trials of recovering a screen! It was my concern that there would be enough residue on the screen to cause new photo emulsion or screen filler to not adhere properly, but apparently this was not a problem. I am able to happily say that with a fresh coat of photo-emulsion my friend’s screen turned out perfectly. My only regret is that I didn’t take any pictures! Ah well; this might be a project for a screen with a stencil on it I left out all last summer. Rev up yer toothbrushes!

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