Walt Goettman (wgoettman@mm.wyeth.com)
Thu, 14 Jan 1999 09:12:06 +1008
> 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.
I have been curious about this. My experience so far has been that I
don't see a difference in gravure tissue sensitized with a fresh or
older(Months) solution. It turns to a brownish color when depleted and
I have always reached depletion before any noticeable loss in speed or
change in contrast. I was taught to store it cold and mix with
distilled water. I did once experience a white precipitate which I
could never figure out.
Walt
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