Re: Dichromate solution Life span

Luis Nadeau (nadeaul@nbnet.nb.ca)
Thu, 02 Apr 1998 16:20:32 -0400

At 11:26 AM -0700 98/04/02, Wayde Allen wrote:
>I finally got back to tinkering with carbon printing this week, and
>discovered that my 3% solution of potassium dichromate had coated the
>bottle with a brownish black sediment. Is this normal? I strained the
>solution through a coffee filter, and scrubbed the inside of the bottle to
>remove as much of the sludge as possible. A couple of sample prints made
>using the solution seemed to turn out OK, but I'm wondering how long I can
>expect this solution to last?

For monochrome work, solutions last quite a while. Factors include the
purity of your dichromate, the water used, the formulas of the tissue which
may contain soluble organic materials (sugar, etc.) and of course, the
amount of use.

As you use the same solution over and over, your tissues will be less
sensitive and will gain in contrast. You can make up for this by changing
the formulation of your pigmented emulsion. See my books on the subject.

For this reason, when doing three-color work, you should use one-shot
solutions and the colors always have to be sensitized in the same order.
Save the dichromate for less critical monochrome work.

Luis Nadeau
NADEAUL@NBNET.NB.CA
Fredericton, New Brunswick, Canada
http://www3.nbnet.nb.ca/nadeaul/