Re: Gum prints with an enlarger (UV loss)
Donald Nelson~ (dnelson@sedona.intel.com)
Mon, 15 Jan 1996 12:58:32 +22306039 (MST)
>
>
> > At one time I thought about using plexiglass for my gum
> > bichromate printing frames. The person at the supply house
> > confirmed that most plexiglass is formulated to absorb UV.
> > However, he also mentioned that there is a UV-T (UV
> > transmitting) variety of plexiglass that should work well for
> > our purposes. Unfortunately, I would have had to special
> > order it, ...and buy a 4 foot by 8 foot sheet. That was way
> > more material than I needed, and due to the costs involved, I
> > lost interest. Has anyone had any experience with UV-T
> > plexiglass?
>
> I have a Gravity Works contact printing frame that comes with UV
> transmitting plexiglass. I have used it for making platinum prints and
> found no significant difference in printing times between it and glass.
> I was using unshielded black light tubes for a light source. There may
> be enough UV blocking in the glass of the tube itself that it wouldn't
> make any difference. I never tried it with sunlight where their may be
> more of a printing speed difference.
>
> One major problem with it is the plexiglass is not rigid enough to provide
> good contact between the negative and paper. There were bubbles of
> unsharpness in the prints where there wasn't good contact. I wouldn't
> recommend it.
I've seen this same problem with both gravity works and premier frames-
the glass/plex just isn't strong enough to be rigid. BTW- on silver contact
prints, those areas of unsharpness turn out to be filled with Newton Rings
Don
>
> John Sparks
>