[alt-photo] Re: Chlorox Bleach Development of Gum

[Ian Hooper]

Most 'household' bleach contains some sodium hydroxide which is not kind to
cotton fibres, but can be removed by a wash in a slightly acidic bath -
diluted vinegar will do.

-Ian

-----Original Message-----
From: alt-photo-process-list-bounces at lists.altphotolist.org
[mailto:alt-photo-process-list-bounces at lists.altphotolist.org] On Behalf Of
pfriedrichsen at sympatico.ca
Sent: January 13, 2010 2:04 PM
To: The alternative photographic processes mailing list
Subject: [alt-photo] Re: Chlorox Bleach Development of Gum


Has anyone tried using an alkaline bath instead of the bleach?.

I haven't tried the bleach development but I have been working with "gum"
subing gelatine, or casein, and the print clears more readily as the
developer is made more alkaline. Salts I use are Sodium Bicarbonate for a
mild alkaline  solution pH of about 8, or Sodium Carbonate with a solution
pH of around 10.

A dilute bleach solution that I made up using about 200 ml water to 20 ml
household bleach gave me a pH of 11.2. This is very alkaline. 
 From what I understand, an alkaline pH changes the charge of particles and
cellulose, so they start to repel each other hence the alkalinity of most
detergents.

This would be good because it would avoid the use of hypochlorite which is
hard on cellulose fibers. This is just a hunch.