Re: "speckling" v "staining "

From: "Christina Z. Anderson" <zphoto@montana.net>
Subject: Re: "speckling" v "staining " (was New Orleans/glut)
Date: Mon, 05 Sep 2005 08:59:39 -0600

> I don't have a comparison of toxicity of the two agents, which I
> wish I did, and can't remember if someone posted as such in the
> past. All I remember is that one poster made the very good point
> that glyoxal is NOT a safe chemical, either. So why are we hanging
> over a TRAY of the stuff as an afterbath??

Comparing toxicity of X and Y is never precise. What if X attacks
brain and Y attacks respiratory system? What if X goes through the
skin or other modes of direct contacts only, but Y can be inhaled?
Oral toxicity for 50% death is a common measure of toxicity and it is
a good way to compare potency of agents, but there are other factors
that need to be considered in practice. The method of use, the typical
amount used, etc.

> In the next couple months I want to finalize my decision on size of
> choice to teach next semester--I may end up teaching acrylic, for
> all I know! It's not like the students can size outside in the
> winter in MT..and as a prof I want to be verrry on top of toxicity
> issues.

If you (and others) are seriously interested in bisepoxide hardener, I
can talk to one of the internet based photo chem dealers to carry one,
with some instruction on the label (to use as a hardener). Same for
glut. But without direct expression of interest and someone taking
action, I don't think that compound will be available for
photographers forever.

Bisepoxide hardener works very well with no fumes but the main
drawback is that you can't use the sized paper for a week.

Ryuji
Received on Tue Sep 6 20:04:09 2005