Re: warning Re: gum mixes
Judy,
Contrary to rumors, I don't have an orange tongue from licking
dichromate.
It is very true that we need to exercise caution when handling
chemicals. Warnings are indeed included with almost every alt process
directions these days. But I have yet to see dichromate in powder
form - what I use is in crystal form and with the same respect I have
for any other photo chemicals, I don't find the danger of inhaling it
unless I stick my nose into the crystal and clearly I don't do that.
I prefer to use about 1/8 of dichromate in dry form for gum as
compared to using saturated solutions. Didn't we go over this many
times in the past? I can't understand why one would use more
dichromate than necessary to do the job, except because the folks who
wrote the literature way back when said to do so. They obviously did
not see the danger of dumping more dichromate down the drain way back
then.
The degree of dichromate concentration does affect the contrast. This
is no longer a problem. With digital negatives one can easily
accommodate the change. Just do a test with the step tablet. Speed
does not change very much, except in extreme cases.
It would be a better world if we all dump less dichromate down the
drain, and one way of doing that is to use smaller amount of
dichromate instead of saturated solutions. Using dry crystals is the
easier way to accomplish that.
Sam Wang
On Jan 4, 2008, at 3:06 PM, Judy Seigel wrote:
Re dichromate:
I hesitate to mention this, it's well known, a discussion we've had
before, and Sam Wang is the picture of health... still in the
context I think it needs saying -- and Chris, if you don't put
caveats in your book, there will be repercussions. That is, if you
cite use of dry bichromate without serious warnings, I would
hesitate to put it on a reading list without reservations, and it
could run into trouble with the safety police at any heads-up school.
That is, dry dichromate is the form in which dichromate is most
dangerous -- by inhaling. Presumably our senior gum printers are
well aware, and take care accordingly, and/or have the pulmonary
powers of dromedaries and the lungs of deep sea divers. Chrome is
one of the two most allergenic materials to humans and handling the
dry chemical is the time it is most likely to get into the air &
hence your lungs. (For that matter, any dry powder, even baby talc
is potential grief...as is also well known.)
It should be spooned out, not shaken out, a long-handled instrument
used so skin doesn't touch, and all surfaces, including bottle neck
and table, damp-wiped after each use, etc. etc. etc. Cloths
disposed of in closed containers, hands never in the mix.
(Incidentally, it was commented about that AWFUL you-tube video on
gum [Charlie Chaplin photographs a naked lady for clip art] that he
wore no gloves -- actually during the wash period, that is, hands
in the wash water, even Charlie wore gloves. And trust me, he
wasn't that fast -- they'd speeded up the camera.).
But it's anyway far better to make a strong mix in liquid and
dilute as and if necessary -- quicker, safer and keeps indefinitely
in solution. plus wherever it is is always visible. (The fine dry
powder is not -- and it does enter the air.)
We breathe enough crap in this world we can't help, why
deliberately up the poison?
J.
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