Re: polymer plate drying time
On Mar 16, 2007, at 10:50 PM, Jon Lybrook wrote:
Keith Taylor wrote:I dry the OHP in the film drying cabinet for 20-30mins low heat prior to use.Ooh...
Around 12-14" square.
Do you use actual talc, or baby powder? I've found that real talcum powder is difficult to find - though I used some in Florence. Much more chalky and coarse than baby powder -- at least the batch I had access to.Baby powder. I use a drafting brush - one of the large, soft brushes with a long handle you can get from an art store and that's used to clean technical drawings - to move the powder around. Could you be leaving too much powder on the plate? After I've finished with it there's hardly any indication that the powder was there.
On Mar 17, 2007, at 9:55 AM, SusanV wrote:
I have a bug bulb placed at the back so I can watch the film and plate come in contact, and yes, I see the shapes and patterns too! The gauge on the vacuum frame indicates 22 in Hg nearly straight away, but it usually takes around three minutes for the patterns to disappear and the film/plate to be in perfect contact. During all this, the pressure doesn't fluctuate at all - it remains constant at 22" Hg, so I've learnt to use my eyes and not rely on the gauge.I rigged a striplight under my exposure head so that now I can really watch the positive as it gets sucked down against the plate. What I see are lots of little irregular shaped areas that move and change shape, and they're colors are rainbow-like and change... I think it's a Newton's rings kind of thing. (and no I haven't been smoking anything :P ) The shapes are larger in the beginning, then get smaller but more numerous as the vacuum continues. This is SO hard to describe, haha. Do you all see anything like that happening?