Re: glyoxal v. formaldehyde

[Alberto Novo <alnovo@inwind.it>]

> But formaldehyde was hardener of choice for circa 100 years... there
> didn't seem to be a problem with it coming undone -- if that's what you
> mean (?) IME, it's at least as permanent for hardening as the others.

I would add two things from my experience.
1) as Ryuji Suzuki pointed out many times, a 20 cc/litre of formalin (or glyoxal) is about 40 times what is (or was...) used by the photographic industry for hardening gelatine films (0.5 cc per litre). The difference is that the films are/were allowed to ripen for some months, while the alt-photographers wants to use his paper asap.

2) when I sized for the first time, I used formalin outdoors because I knew its dangerous properties. I left the sheets overnight on a clothes line, then I packed them in an old photographic plastic bag inside its cardboard folder.
After years, if now I open that folder I can distinctly smell it.

My suggetion is to plan how many sheets you need and seize them some months earlier, cutting the amount of hardener.


> What you didn't mention however is that allegedly glyoxal is nearly as 
> toxic as formaldehyde, but we don't notice it because we don't smell it.

I am more worried from what does not smell than the contrary...

Alberto