I'd like advice on building an exposure unit, and anything else related to screenprinting.
August 26, 2004 3:22 PM   Subscribe

Amateur screenprinters! I am considering building my own exposure unit (for fine art screens -- i'm not trying to start a shirt business). I could use your advice on this matter and anything else related to screenprinting (i'm not completely new to this, but all input is valuable) {mi}.

I produced a number of screens a few years ago in my college courses using high wattage lights, but the exposure times were inconsistent and dreadfully long. Now, since I'm making screens for fine arts applications, I don't really care about registration or absolutely picture-perfect exposure (i'll probably be using really rough halftones on my positives), but I *do* care about exposure time. I *hate* spending 15-20 minutes hovering over a screen with a floodlight hoping that the end result will be good enough to bother printing. To that end, I'd like to create a home exposure unit in the $50-100 range (more time than money here; I know I can expose using just the sun, which is free, and I know and I have burned screens with $10 bulbs, so I don't want to spend a fortune making the process easier, but I wouldn't mind spending a hundred bucks to get my ideas on to screens more quickly) and get, at the least, a process that 1) produces usable screens on a regular basis (again, doesn't need to be professional -- i don't need vacuum seals here, or super-fine definition) and 2) is primarily unattended and/or fast. The best I've been able to find on the web so far is this home-brew. My other option was to try the whole Gocco Screenprint Kit dealie, but after some investigation it seems they are too expensive and not versatile enough for my applications (although I like the idea of going from positive to printing in 10 minutes, it seems like the screens aren't reclaimable, and either way, incredibly tiny. Also, it sounds like the bulbs are one-use only too. Lame!). Mostly I want to know about lights. I've heard special UV lights can work (but the ones recommended were in the grainger catalog and crazy expensive), and the model I linked uses a mercury vapor bulb. My friend has had decent success with halogen lights (suprising, because sources on the web mention that they contain the *least* amount of light necessary for the conversion -- and fwiw, the screens he made with those had a *lot* of clogging problems and fuzzy edges).

Also, in a related question -- how about some emulsion suggestions? I've always used diazo, but I've heard that the diazo-photopolymer mix is quicker to expose and still relatively easy to work with. Has anyone had experience with it?

Other stuff: any good sources for screenprinting equipment? I've found ebay has a wealth of products, but I wouldn't mind a consistent source. So far, this is all I've found. Oil inks vs. water-based? Anything! (particularly advice from a fine arts perspective. it doesn't need to be perfect, and I'm interested in alternative techniques).
posted by fishfucker to Media & Arts (7 answers total)
All I can suggest is to use water based inks. Oils will need to be cleaned with turp, and to do that safely you need industrial strength ventilation, or the fumes can build up and kill ya. Or explode.
posted by slipperywhenwet at 4:42 PM on August 26, 2004

Response by poster: really? we've had really good luck cleaning them with soy solvent or whatnot.

which, i don't know, sounds sorta non-explosive.
posted by fishfucker at 4:58 PM on August 26, 2004

I'm very new to the process, having produced only a handful of prints. I've had decent success with a pair of clip lights - I can't find a link, but you can get them at any hardware store - and some 500 watt bulbs. Timing is a bit experimental, but more often than not the screen comes out decently.
posted by aladfar at 6:48 PM on August 26, 2004

go Gocco! I was gonna suggest it if you didn't mention it yr'self.

It's amazing and and easy to operate as a polaroid camera. Flash bulbs inside the unit, too.
posted by Peter H at 7:17 PM on August 26, 2004

Response by poster: thanks for the help guys. I've been finding pretty good information on this screenprinter's board if anyone is interested. I guess it's just a matter of muddling through it myself.
posted by fishfucker at 7:55 PM on August 26, 2004

Response by poster: screenweb
posted by fishfucker at 8:15 PM on August 26, 2004

Best answer: ok, booya. Sorry to fill my own thread, but this took me near-on 4 hours of googling and reading (darkweb indeed!)

pics of a halogen based exposure unit

here's the material rundown from the author.*

after reading through those (terribly built) forums for awhile it seems that although halogen isn't the *best* way to go (metal halide seems to be the favored choice), it is certainly the *cheapest* -- and as I said, I'm not super picky about quality. If I get anything done before this thread closes, I'll try to come back and post my own results.

* the 4-6 blacklight tubes that the author talks about would probably cost approx. $20 x tubes (base is $10 at home depot, bulb is around $6-10 -- you apparently don't want the blue colored ones that stoners keep in their closets, because that cuts out part of the UV light range you want), so $80 just for the tubes, before any table is built.
posted by fishfucker at 9:07 PM on August 26, 2004

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