U of S | Mailing List Archive | alt-photo-process-l | RE: Hardening With Glyoxal: One Shot?

RE: Hardening With Glyoxal: One Shot?

Hi Ryuji,

I once refrigerated 8% gelatine solution (plain, w/o any biocide +
hardener) and reused it two weeks later w/o any problems. More AFAIK, in
carbon printing, it's a common practice to prepare the "glop" (gelatine
+ sugar + pigment + optional: glycerol) beforehand and remelt it when
necessary... How do you explain this fact?


-----Original Message-----
From: Ryuji Suzuki [mailto:rs@silvergrain.org] 
Sent: Monday, May 07, 2007 10:33 PM
To: alt-photo-process-l@usask.ca
Subject: Re: Hardening With Glyoxal: One Shot?

Gelatin solution does not keep very well even if refrigerated, unless a
small amount of biocide is added. A couple of days may be ok but
bacteria grow very well on gelatin solution. They break down gelatin
molecules to smaller molecules and their gelling property is affected.


Compounds that hardens gelatin molecules should not be counted on
because they bind with gelatin molecules and not available to kill
bacteria. Ones that are photographically inert and don't react with
gelatin should be added, if the sizing solution is to be kept for later

Hardener is best added immediately prior to coating, as already