RE: Dichromate dilution and speed

I forgot to mention an important factor: I'm using lith negatives. Which
brings up a point: in the past, I've used digital negs, but never
Pictorico. My negatives are rather contrasty and dense. Sandy, are Sam's
negatives anythng like yours? When I saw your negatives in person, I was
very much surprised that they produced the (very fine) results you obtain in
your work. They seemed very thin - nothing like what I use.

-----Original Message-----
From: Keith Gerling [mailto:keith@gumphoto.com]
Sent: Monday, December 01, 2003 12:23 PM
To: alt-photo-process-l@sask.usask.ca
Subject: RE: Dichromate dilution and speed

Given the recent exchange, I thought I might as well offer my comments.
Typically, I use a saturated solution of Potassium Dichromate for my gum
work. But after reading Chris's account about using weaker solutions, I
performed a series of (albeit un-scientific) tests. Working with a negative
that normally requires 600 units under a Violux plate burner, I tried it at
700 units with an emulsion using half the amount of Pot Di, making up the
difference with tap water. After 30 seconds in the water, the emulsion had
totally dissolved. All of it. Increasing the exposure to 1000 units
produced a abominable result: very posterized with no emulsion on most of
the print all of the emulsion remaining in the shadow areas. I was very
disappointed.
Received on Mon Dec 1 12:31:28 2003