Re: Chrome Alum Gelatin hardener

From: Suzu Sn <bromideshi@yahoo.co.jp>
Subject: Re: Chrome Alum Gelatin hardener
Date: Tue, 10 Feb 2004 18:35:42 +0900 (JST)

> Perhaps I skipped a line, a page or two?

I think you are skipping a lot.

> In any case, I am more interested in direct proof rather
> than inferences and conjecture. If the bonds are that
> fragile, I think such will have been reported.

Indeed, this is why the focus of aldehyde hardeners in literature in
1970's shifted to the mechanism of hardening with glutaraldehyde,
because this mechanism is different from that of formaldehyde or
glyoxal. You really need to see literature from late 70's to get any
details on glutaraldehyde hardening mechanism. For example, books from
1960's (like Zelikman and Levi, Duffin, James 3rd edition) still spend
a lot more words for glyoxal because that was where knowledge was
limited to. James 4th edition spends a few more paragraphs with a few
more references to glutaraldehyde. Anyway, literature is very clear
about superiority of stable crosslinking made by glutaraldehyde over
less stable crosslinks made by glyoxal. I wouldn't say it's speculative.

> If not, then I do not see why you are knocking
> formaldehyde on the basis of its cross links.

For silver gelatin process, formaldehyde has more direct disadvantage
like tendency to fog, reduce speed, or both, especially in fast
emulsions. I wouldn't use it.

--
Ryuji Suzuki
"Reality has always had too many heads." (Bob Dylan, Cold Irons Bound, 1997)