Re: About sizing gum: Hey -- READ THE LIST !!!

[Judy Seigel <jseigel@panix.com>]

On Wed, 19 Aug 2009, phritz phantom wrote:

> i saw this mentioned before, among others by sandy king. when i first ordered 
> the chemical, i looked around, if there was any info available on the 
> toxicity, precautions when handling... etc. but there wasn't much info 
> available. to my understanding (from what i was able to find out), chrome 
> alum is a chrome (III)-compound, which are not as toxic as chrome 
> (IV)-compounds (such as the dichromates). there aren't any hazards mentioned 
> on the english and german wikipedia pages. but i don't know, if there really 
> aren't any, or if just nobody added them yet.
> effects on the water table could maybe be neglected, since most of it should 
> stay on the paper (within the gelatin size) anyway.
>
> but maybe someone more chemistry-literate than me could shed some light on 
> the whole thing.
To date, in my experience, only one of the alums gets a pass (tho to save 
my soul, I couldn't say which)... Meanwhile, tho most of what I know about 
the topic is word of mouth, or conventional "wisdom," which we all know is 
a frail reed, it occurs to me that in the long ago Mike Ware wrote 
something about chrome in water turning into stage 3, which is, he said, 
harmless... (That of course is a garbled version and not to be quoted.)

HOWEVER, I do have a better idea about glyoxal, as by the time it gets 
into the water, it's reduced (or like that), plus we never got the 
warnings about it we got about alum. Also, I've used glyoxal for years and 
can still, casually, not even trying, bite heads off.  (If I find that 
book about health hazards in photography, I'll look up alum, tho that lady 
can make gelatin and gum arabic sound like death bombs.)

cheers,

Judy