Luis Nadeau (nadeaul@nbnet.nb.ca)
Sat, 23 Jan 1999 20:42:18 -0400
At 4:33 PM -0700 99/1/13, Wayde Allen wrote:
>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: I doubt it. Gelatin should not dissolve in a cold sensitizing bath
(15C+/-)
What dissolve are sugar, dextrine, and watever is dichromated water soluble
in the "tissue" paper. I thought I had explained this in my books, but
maybe not. They are not at hand at this moment.
Luis Nadeau
NADEAUL@NBNET.NB.CA
Fredericton, New Brunswick, Canada
http://www3.nbnet.nb.ca/nadeaul/
http://www.phxinternet.net/users/dbarto/lnadeau.html
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