Re: polivinyl alcohol vs. gelatin sizing

From: henk thijs <henk.thijs@hetnet.nl>
Subject: Re: polivinyl alcohol vs. gelatin sizing
Date: Sun, 31 Jul 2005 00:21:33 +0200

> When I asked him why he used it instead of gum
> arabic, he said that he disliked the formaldehyde used to preserve the
> gum .

That doesn't sound quite right. There are lots of biocides that are
easy to use and effective other than formaldehyde. Also, poly(vinyl
alcohol) solution should have preservative if the mix is to be
kept. An industrial chemist could quickly advise what to look for, but
below are my preferred agents for photographic use:

2-phenylphenol, 1,2-benzisothiazolinone, n-butyl-p-hydroxybenzoate,
phenol, 2-(4-thiazolyl)-benzimidazole, 4-chloro-3,5-dimethylphenol,
2-phenoxyethanol, etc.

2-phenylphenol is very effective as bactericide as well as fungicide
so this is usually my preferred choice. Toxicology of this agent is
one of the most well studied among industrial biocides and I feel it's
very safe and effective. (I don't know about current US situation but
this agent was used for post-harvest treatment of citrus fruits. This
agent is also easily purchased as an acrylic paint additive. Major
producers: Bayer and Dow. You can buy this from Kremer Pigmente in a
small bag.) I prefer isothiazolinones or other agents when the
solution to be preserved must remain acidic. This type of agents (not
the 1,2-benzo substituted one) are very often used to preserve skin
care products and personal products (shampoo, etc.) as well. Some of
those agents can be useful for photographic applications as well.
Major producer is Roam and Haas.
Received on Sat Jul 30 16:41:21 2005