Re: dichromate stain

Just another attempt to clarify what it is I've been trying to say. This
discussion started with people trying to explain, or in some cases
explain away, the fact that I say I don't get dichromate stain. Some of
the explanations offered, while they may explain why some people get
dichromate stain under some conditions, do not explain why I don't get
dichromate stain.

When I say I suspect it's most likely related to the light, I don't of
course mean that I think all dichromate stain in the world is related to
the type of light!! What I mean is that I've ruled out all other
reasons and that's the one that seems most likely to me to explain this
particular aspect of Katharine Thayer's practice, the fact that I don't
ever get dichromate stain.

Most of the other explanations given here simply don't apply in my case.
Higher dichromate concentration causing more staining, for example,
doesn't work because I use the highest concentration available in the
usual dichromates. Exposing for a softer gum I've already disposed of: I
don't. The fact that I don't ever overexpose to the extent that I get
dichromate stain is a reasonable explanation, but the reason for it is
the kind of light I use, which hardens gum well, and can overexpose
grossly (shown by the fact that I sometimes overexpose to the extent
that I have to soak for a day or two to develop the shadows) without
ever producing dichromate stain.

Yes, I have seen dichromate stain sometimes as a result of certain
combinations of sizing and paper, when I was testing paper. I've said so
here and I say so on my website. And I've seen dichromate stain as a
result of certain gums. Again, I have a demonstration of this on my
website. I rather suspect, though, that in the first case, some of the
stain I saw when I was testing papers (this was a bright yellow
hexavalent chromium stain that just grabbed onto the paper and wouldn't
let go until cleared with a clearing agent) was because I was on
deadline and I had to pick another paper fast so I could get the prints
done, and some of that sizing may well not have been completely dry when
I printed the tests on it. This suspicion is rather supported by the
fact that months later I printed on some of those test papers and they
turned out to print fine.

Katharine Thayer
Received on Tue Jun 15 12:20:15 2004