[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: chemistry question--Sil, et al?
Content-transfer-encoding: 7BIT
At 2001/04/02 09:20 AM -0600, Chris wrote:
>Short and sweet, for all you chemists out there: if there is a drip of
>bleach/etch (copper chloride/acetic acid/hydrogen peroxide 20-40 vol) that
>wanders into non hardening rapid fix (ammonium thiosulfate, sodium acetate,
>boric acid, and acetic acid), what is the horrible smell that occurs and
>does it produce any toxic gas that I should be worried about (in other words
>does it just reek but it is fairly harmless to the lungs? I, of course, am
>wearing gloves)
I wanted to keep out of this, but duty calls. The horrible smell may be a
pretty deadly mixture of hydrogen sulfide (rotten egg smell), plus some
complex sulfur gases such as sulfur dioxide (this is the smell you get when
you add unbuffered acid to hypo), and possibly some ketones, with a mix of
other goodies in the organic group. The boric acid introduces another
variable, as boranes (which are truly deadly) can be produced in this
environment. I would definitely take great pains to keep the strong
peroxide out of the fixer, because it is a very active oxidizer and can do
all kinds of things to photographic solutions.
On the other hand, I am annoyed by the warnings about hydrogen peroxide.
When this decomposes, the chemicals produced are water and oxygen. Unless
you are using a very high strength peroxide, the amount of those two
ingredients would have minimal effect. Anyone who uses and/or mixes
chemicals that have any gaseous component or end result should definitely
have a good ventilation system.
Sil Horwitz, FPSA
Technical Editor, PSA Journal
teched@psa-photo.org
silh@earthlink.net
Visit http://www.psa-photo.org/
Personal page: http://home.earthlink.net/~silh/