From: Judy Seigel (jseigel@panix.com)
Date: 04/28/00-08:45:34 PM Z
On Fri, 28 Apr 2000, Alan Elliott wrote:
> In addition to the poisoning if ingested and the problems of disposal, the
> most insidous potential hazard with dichromates is that repeated contact
> may cause dermatitis. This is a serious risk which, if contracted, will
> cause skin irritation and possible ulceration and put an end to your gum
> bichromate work for ever! Such allergy rarely is cured and the slightest
> exposure to dichromate will cause a recurrence of the attack. Of particular
> importance is that the dust should not be inhaled. Repeated inhalation of
> the dust may give rise to perforation of the nasal septum and respiratory
> problems.
You're singing my song. Except in my experience, the poison of "ingestion"
isn't so crucial. I mean you're unlikely to eat enough of it to matter
unless you're feeling suicidal. (They used to use it as preservative for
sausages during WW I.)
But chrome is one of the most allergenic substances to humans. In our
usage the risk lies in getting hands in the emulsion OR washwater -- even
a supposedly "clean" washwater. At first this wasn't understood & many
dichromate workers got TERRIBLE TERRIBLE skin lesions without knowing the
cause. In time, it's said, nearly everyone gets allergic to chrome, but
some factory workers did seem to tolerate it for years (they died young in
those days) so it was a while before the cause was understood. Now it's
known and IN THE LITERATURE that even miniscule amounts CAN cause bad
sensations by CONTACT. But some people insist on macho.
However, once sensitized, indeed there's no going back. It's over. Still,
speaking as one with about the most sensitive skin since the princess and
the pea, I note that by good work habits and of course some luck, I can
(knock on wood) after quite a few years continue without noticeable
effects.
Again, I mix up 200 ml of the stuff once a year or so, and don't think the
powder (just don't fling it out of the jar, spoon it out) that often is
the great risk -- but one thing to pay attention to is the neck of the
bottle. containing the mixed solution. Wipe that early and often because
the tiniest drip is soon a deposit of crystals.
And DRY HANDS. You don't feel anything at the time -- but sometimes I'll
feel a burning itch in one spot say on my foot & know there's been a
splash from the tray. Or if you accidentally do get on skin, which happens
-- IMMEDIATELY wash with soap and water, and at least in my experience no
harm done. (So far.) I also when I have any trash with dichromate stain,
even a few drops, remove from studio -- don't leave around to dry into my
air.
An 8-oz dropper bottle is very efficient dispenser -- less pouring and
contaminating of intermediate vessels... etc.
Judy
.................................................................
| Judy Seigel, Editor >
| World Journal of Post-Factory Photography > "HOW-TO and WHY"
| info@post-factory.org >
| <http://rmp.opusis.com/postfactory/postfactory.html>
.................................................................
>
> So--- Wear impervious gloves (the disposable type from the supermarket are
> fine) when handling dichromate in solution and, in addition when weighing
> out the powder, wear a dust mask. Preferably avoid handling the powder in
> enclosed space. If you cannot find a suitable place outdoors you may be
> able to ask a chemist who has access to a fume hood to weigh out and
> dissolve the powder for you. Do not allow spills to dry and thus release
> dust into the air of your workplace. If you do happen to come in contact
> with chromium compounds wash immediately.
>
> If you imagine that the above is exaggerated, believe me it is only too
> true. I know of at least one gum bichromate enthusiast who has taken no
> prcautions and has had no problem - as yet. Therein lies the trap. Users
> are led into a false sense of security. From experience as a consulting
> chemist I can site cases where workmen have contracted contact dermatitis
> from the chromium compounds in cement, from handling galvanised iron sheet
> passivated with dichromate, from wearing chromium tanned leather gloves and
> from handling bags of dichromates in intustry. It is the repeated contct
> which causes the problem. Please take care!
>
> Alan Elliott
>
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