U of S | Mailing List Archive | alt-photo-process-l | RE: haunted GUM (update)

RE: haunted GUM (update)

Hey guys ... everybody is just clicking "return" without cutting out anything from yesterday, last week, last month, etc.... and the whole chain is now about 38 kilibusters long... Those of us without megacarats may be suffering...

Meanwhile, I'll add the thought that keeps knocking at my door: Is the new potassium di from the same supplier? Even if so, I find that a new batch of even supposedly the same chemical from even the same supplier can be different from the previous: maybe stored differently, made by a different dreamer, or whatever. I admit I haven't followed the precise unfoldings (all hell has broken loose on the home front, a regrettable distraction from reality), but I've foound that a new chemical, whatever the source, may well have a mind of its own.... It's even possible that its anomalies are as valid as whatever came before.


> > Phritz,

A bad batch of dichromate is definitely a possibility. If it is contaminated with Cr (III) salts, which you would not be able to tell with the visual inspection it would definitely act to cross-link gum on contact resulting in overall chemical fog. That is the easiest way to think of the phenomenon: a chemical fog. Everybody can relate to this from their earlier, traditional photography days. Another possibility is the way you size the papers, since you are using Cr(III) as a hardening agent. Maybe something changed in your sizing procedure. Do you soak the paper after it has been sized and seasoned to remove any Cr(III) that could act to cause chemical fog in the gum?

I have not been able to read and digest all the posts on the subject just yet.