From: Judy Seigel (jseigel@panix.com)
Date: 02/29/00-07:41:40 PM Z
On Tue, 29 Feb 2000, Art Kerbs wrote:
> Has anyone out there in Alternative Photo Land have the definitive answer
> as to what n/m UV, gelatin sensitized with potassium dichromate is most
> active with?? 300, 350, 400?? going on the premises that there is no glass,
> Mylar, film over the tissue. just the sensitized tissue.
> Thanks for any response
> AK
>
The consensus of various sources is 365 nm, but in my experience that's so
theoretical as to be purely theoretical. In the 1st place, there are
different spikes of different heights in different places according to
light source, and these have a DEFINITE effect on the "curve." In the 2nd
place, I have found that different *colors* respond differently, so again
a "general rule" is going to be theoretical.
And those are just the first 2 places come to mind. There's also the fact
that sensitivity for gum printing & carbon printing, both "dichromate," is
different -- the response to light source VERY different, as Sandy King &
I found with some bulb tests a few years ago...
And so forth.... Which is to say, for anything resembling a "definitive
answer" you have to define your variables VERY precisely, and then ....
no guarantees.
Why do you ask?
Judy
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| World Journal of Post-Factory Photography > "HOW-TO and WHY"
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