Sandy King (sanking@hubcap.clemson.edu)
Wed, 13 Jan 1999 18:23:31 -0400
>On Wed, 13 Jan 1999, Judy Seigel wrote:
>
>Henk, my assumption would be that it was the gum, not the dichromate.
>Because even tho dichromate solution may change with age, it gets weaker,
>and the print still clears. (I found about 20% slowing in a year, but
>since I print "by eye" most of the time anyway, doesn't matter much.)
>
Judy,
I don't have the research on hand, however, what I have read about
dichromate solutions indicates that if mixed with distilled water they are
stable for very extended periods of time, even years. My own expereince
confirms this. I always mix the stock solutions with distilled water and
store them in bottles in the dark, or at least in subdued light. Although I
have conducted no controlled testing to verify the scientific truth of my
assertion, I have not seen any discernible difference in printing between
solutions mixed several years ago and those mixed within the last few
months. How did you arrive at a figure of 20% slowing a year in age of
dichromate solutions? I don't recall ever seeing anything like this in
print.
Sandy King
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