Re: printing gum on glass
Marek, what dichromate concentration are you using? that would make a difference, of course, to the exposure . Also, the variation in intensity from place to place. If I remember right; you're in Houston? Your sun is probably more intense than mine in the Pacific Northwest. I lived on the coast when I last did exposures in the sun for gum on glass; as I recall they were a minute or less with a fairly heavily pigmented mix of lamp black; that's with saturated ammonium dichromate.
I tried exposing from the back on regular picture glass, after our thread about back-exposing on plastic a year ago or more, and found that while the exposure worked well (the gum adhered well to the glass with back-exposure) the thickness of the glass between the negative and the gum resulted in a loss of sharpness and detail, which didn't work very well with the image I chose. I still think that's the best way to go for printing on glass, as you say, but it needs to be the right kind of image that won't suffer too much from not having direct contact between the negative and the emulsion; perhaps a composition depending on abstract shapes rather than fine detail.
On Jul 17, 2007, at 11:59 AM, Marek Matusz wrote: