Re: gum bichromate
Luis Nadeau (nadeaul@nbnet.nb.ca)
Fri, 9 Jun 1995 20:23:13 +0300
Kotsikonas
>> X-Comment: Alternative Photographic Processes mailing list
>>
>> I used this process about 12 months ago using saturated potassium
>>bichromate &
>> gum based glue. It worked though not very consistantly. Unfotunately I
>>did not
>> follow this up until now when it doesn't work at all! Is this because my
>> bichromate solution is old? If any one who has experience of using this
>> process could give help or advice on the best and most consistant methods of
>> gum bichromate printing it would be most appreciated
>> thanks, Anthony
>
>It's hard to offer specific advice without more information, but one
>thing to watch out for is humidity. If there is too much, the image
>won't "develop" (wash out). Generally, the lower the better, but
>best is a constant relative humidity level somewhere below 50%.
>
>I haven't heard of a dichromate solution getting too old to use.
An unused (important) dichromate solution, kept in the dark, should last years.
I think the problem is that he makes a SENSITIZED SOLUTION OF GUM and that
indeed will not last at all. You should combine the sensitizer with the gum
(or whatever colloid) just before use, and the mixing should be done under
a safelight, or "bug bulb", although I understand the latter is not
available in Europe.
Luis Nadeau