From: Kate Mahoney (kateb@paradise.net.nz)
Date: 07/15/03-12:46:56 AM Z
Hi Christina, you will probably find that the reason that the amm di stains
more than the pot di is that you get a more saturated solution with amm di -
more chemical in the mix, therefore more staining!
Kate Mahoney (New Zealand)
----- Original Message -----
From: "Christina Z. Anderson" <zphoto@montana.net>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Tuesday, July 15, 2003 1:16 AM
Subject: Re: GUM TESTING
> Good morning Katharine!
>
> Yes, this is why I even tried it in the first place, because as I had said
> when I originally posted it, if dichromate is sensitive to sun, why would
it
> then bleach OUT in the sun?? I only came across that method in one book,
> and most of the other tidbits I've picked up I've come across numerous
> times.
>
> Anyway, the prints I used were 8x10 one layer exposures (full prints) that
I
> had developed out, dried, but not cleared. These were done presensitizing
> the paper with saturated solutions of the two dichromates, and then
painting
> the pigment/gum/no sensitizer on top of the dried sensitized paper. Thus
I
> had a good border of dichromate with no pigment on top. I was observing
> just the dichromate stain in the borders of the prints. Every time in
> comparison between ammonium and potassium dichromate that border stain
(and
> it literally is a dichromate stain, no pigment) is darker in ammonium than
> in potassium. Thus the ammonium has more ways to go, which is why I
covered
> up half the print to see the difference in bleaching. The potassium did
> bleach out, the ammonium did lighten but was not entirely gone.
>
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