From: Sandy King (sanking@clemson.edu)
Date: 04/10/02-10:00:32 PM Z
Katharine Thayer wrote:
>Kerik Kouklis wrote:
>>
>>
>> For the effect I am after, my gum exposures are typically about 1/2 the
>> time of my platinum exposures. Even when I do a strait gum, if I try the
>> same exposure I use for a platinum print, the gum will be overexposed.
>
>Yes, it would be expected as you report that a negative of whatever type
>would print faster on gum than on platinum, but that's not the question
>at issue here.
If the printing speed is not relevant to this discussion might I ask
what is your reasoning in expecting that a negative of whatever type
would print faster on gum than on platinum?
> I'm talking about spectral density negatives that print
>on gum, even at very short exposures, as if there were no negative there
>at all, resulting in a rectangle of hardened colored gum with no image
>in it. This observation of my own, added to my understanding of David's
>problem in printing pyro negatives on gum (what ever happened to David,
>anyway?) led me to speculate that in one or both of these cases, the
>negative may simply not be adequately blocking the relevant wavelengths
for gum.
I fully expect that anyone who bothers to carry out the experiments,
as I have done, will find that gum and carbon have a similar response
to both conventional and pyro negatives. These tests clearly indicate
that a pyro negative puts up a very effective block to the relevant
wavelengths of both of these processes.
So I think your speculation, while interesting, is incorrect. I would
suggest that there is a much higher probability of some other
explanation for David's result. Perhaps his gum got fogged from the
long exposure - heat from the exposing light for an hour (he didn't
say he used a cooling fan?).
Sandy King
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