RE: [PPLetterpress] Kreene?
- Hi Wayne,
I just spent all weekend working on the same project! I have a NuArc exposure unit of some kind that I'm modifying to do photopolymer with. I built a vacuum table to put in the box that I modeled on the Polimero one that I used to use.
I mounted a scrap of formica on a piece of plywood (I would think a piece of old countertop or even that melamine that they make cheap furniture out of would do) and then scored a grid into the surface with a router. Careful not to run the scores off the edge of the formica, keep an edge of about an inch. I drilled five 1/8" holes through crosspoints in the formica, and ran the vacuum hose to the five holes.
Brian Allen is right about the suction being enough to hold the Kreene down. Every now and then you may get a wrinkle in the Kreene that you have to weight down with a lead slug, but other than that...
I tried using the Kreene on top of a rubber vacuum blanket that came in the exposure unit, and that is designed to be pulled up against glass by the suction. I couldn't get it to seal, even with the Kreene mounted in the frame that had held the glass. My conclusion is that in a vacuum assembly you need one flexible surface and one rigid surface to get a good seal. Rubber vacuum blanket against glass works, Kreene against formica works.
I'm more comfortable making the plates under Kreene because that is how I learned to do it. I'm glad to hear that others have figured out how to do it consistently with glass, and I've taken notes for the future. It is nice to know there isn't only one way to do it.
BTW, I got my vacuum pump second-hand from Harold Kyle at Boxcar Press and I believe he said he had a couple more, if you're looking for one.
From: cutncrease [mailto:wayne@...]
Sent: Sunday, March 03, 2002 4:40 PM
Subject: [PPLetterpress] Kreene?
I've just built myself a neat little A3 exposure unit (8XSylania 350BLs which sit 2 inches above the plate) I'm now attempting the vacuum frame. I've
seen much info about using kreene or pvc instead of glass (which I understand absorbs important UVA). Just wondering if anyone could explain how the
kreene is sealed around a vacuum blanket and frame in order to create good contact between plate and film. Should I be looking at some kind of
snaplock system (like in a vacuum bagging process) or does the sheet of kreene go under a sheet of pvc which is hinged to the frame in a standard
manner. Should I be using kreene in a fluro exposure system or is it for single point light sources only? Any help would be much appreciated.
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