>From: Charles Berger <<cb@ultrastable.com>
>Subject: Re: A Dumb Gum Question?
>To: Judy Seigel <<jseigel@panix.com>
>Cc: SCHRAMMR@WLSVAX.WVNET.EDU, alt-photo-process-l@skyway.usask.ca
>Organization: ultrastable color systems,inc.
>References: <<Pine.SUN.3.94.970622130611.12018A-100000@panix2.panix.com>
>Comments: "alt-photo-process mailing list"
>
>Hello Judy,
>This may/may not be accurate. The light sensitivity of dichromate
>solutions are greatly influenced by the pH of the solution. The highier
>the pH, the lower the sensitivity. Over time, all dichromate solutions
>will show an increase in pH (whtether stored in a dark bottle or not)
>until they get to the point where they are virtually insensitive to
>light. Also, if the stored dichromate solution has turned a dark brown
>over time, it will act a a light-filtering dye, preventing actinic light
>from reaching the sensitized gel/gum layer.
This sounds to me like an off-line comment I made to Judy S. about some dichromate that I had sitting on a shelf that got sunlight for part of the day for several years, and in a clear glass bottle at that. I used it and it worked in reverse, I got a positive image, that is, a negative from a negative. I threw it out before I really understood the implications of what I had. I thought that it had gotten contaminated, which it may have as well. What you are saying makes sense.
This looks like a possible area of exploration.
<<snip>
Dick Sullivan
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Bostick & Sullivan
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