[Alt-photo] Gum pigment mixed in batches

Denny dspector at charter.net
Tue Jan 9 05:28:34 UTC 2018


My understanding is that the dichromate will react with the gum (slowly) in the dark, though I’ve never bothered to test this.

 

From: Francesco Fragomeni [mailto:fdfragomeni at gmail.com] 
Sent: Monday, January 08, 2018 9:12 PM
To: Denny
Cc: The alternative photographic processes mailing list
Subject: Re: [Alt-photo] Gum pigment mixed in batches

 

Sorry, I might have been unclear. I mean specifically mixing premixed emulsions i.e. pre-mixed gum arabic, dichromate solution (i use 13%), and watercolor pigment. I'm asking if I can premix the complete ready-to-coat sensitized solution in batches.

 

You mention not to add the dichromate but why would that be? Does dichromate lose sensitivity or go bad after its been mixed?

 

On Mon, Jan 8, 2018 at 8:54 PM, Denny <dspector at charter.net> wrote:

Francesco,

I routinely mix gum and pigment in large batches and I've had no problems.
Just don't include any dichromate,  and mix well before using each time.

Denny


-----Original Message-----
From: Alt-photo-process-list
[mailto:alt-photo-process-list-bounces at lists.altphotolist.org] On Behalf Of
Francesco Fragomeni via Alt-photo-process-list
Sent: Monday, January 08, 2018 8:45 PM
To: The alternative photographic processes mailing list
Subject: [Alt-photo] Gum pigment mixed in batches

Hi all,

Quick question. I'm sure this has been asked but I can't find it. Can gum
bichromate pigment be premixed in larger batches rather than being mixed at
coating time? I'd like to mix stock pigment solutions and keep them stored
in glass bottles that I can reach for across printing sessions (rather than
mixing fresh for each print). Is there any reason not to do this? I think
I've heard of people doing this but wanted to double check. Thanks!

-Francesco

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