U of S | Mailing List Archive | alt-photo-process-l | Re: gum preservatves

Re: gum preservatves

Here it is:


Scroll down to the very bottom past the color charts.

I'm not saying it proves anything, but acidity may account for some problems that people say are issues with gum, and it is only really meaningful in relation to the water control strips done at the same time with the same amounts of dilution. Otherwise a lot more tests would have to be done to be conclusive. If, as Ryuji and Demachy said, there is a reduction to chromic acid with the addition of lemon juice, which I don't know because I am not a chemist, I don't know if that is speedier or less speedy than dichromate.

Christina Z. Anderson
----- Original Message ----- From: "Loris Medici" <mail@loris.medici.name>
To: <alt-photo-process-l@usask.ca>
Sent: Saturday, September 06, 2008 3:13 PM
Subject: Re: gum preservatves

Thank you!

Now that you say that, I remember the section about it in the "Learn" part
of your former website. (Adding lemon juice and staining... I'm not making
it up right?)

Judy's note on sizes was interesting and real food for thought, BTW.

Ryuji's notes also were interesting -> I mean the probability of citric
acid (or any other organic acids) interacting with dichromate in an
unwanted manner. That powered my original position which was increasing
the acidity by not adding alien compounds... (Still don't know if that can
work or not -> I may do some tests in the future if the exposure times
become unbearable to me and/or I can't do nice casein prints...)


5 Eylül 2008, Cuma, 1:12 am tarihinde, zphoto@montana.net yazmış:

Have at it, Loris.  I found that the more lemon juice drops
I added to the mix (with drops of water added to the control
group in the same proportion) that I got lots of staining of
the highlights and lower contrast, but with paper negs this
might be helpful to you--I mean, the lower contrast part.
Step wedge steps were not too differentiated.

----- Original Message Follows -----
From: Loris Medici <mail@loris.medici.name>
To: alt-photo-process-l@usask.ca
Subject: Re: gum preservatves
Date: Thu, 04 Sep 2008 21:37:54 +0300 (EEST)

David & Chris, that also arrived to my mind just after had
sent my last message... Even if I refrain to introduce
another alien compound into consideration - as a first
impression -, it sounds interesting / promising. You can
bet I will try this (with citric acid)as soon as possible!
Of course there's also the staining issue... I'll see.

Chris, do you know how much lemon juice was Demachy adding
to his gum?