U of S | Mailing List Archive | alt-photo-process-l | Re: warning Re: gum mixes

Re: warning Re: gum mixes


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?