Wayde Allen (wallen@boulder.nist.gov)
Wed, 13 Jan 1999 16:33:52 -0700 (MST)
On Wed, 13 Jan 1999, Sandy King wrote:
> 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.
This has been my experience as well.
About a year ago, I asked this list, and some very reliable scientific
sources (a friend who used to grow dichromate crystals) about the
formation of a sludge or precipitate in my dichromate solutions used for
sensitizing carbon tissue. Everyone I have talked to about this subject
noted that if the dichromate solution is decaying it can't be a pure
solution. In my case, the dissolved gelatin from the carbon tissue was
precipitating out.
- Wayde
(wallen@boulder.nist.gov)
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