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>Dichromates are carcinogens. The normal sewer treatment plants do not
>break them down and so they return to the environment. Dust masks
should be
>worn and the granules should be handled in a dust box. Latex gloves
>should also be worn.
> All but
>the most dilute washing solution should be collected, the water allowed
>to evaporate and the remainder sent to a toxic materials disposal
>operation. I am facing this problem because I do collotype. So far I
>have collected a few gallons of sensitizing solution and first rinse
>washing solution and am letting it evaporate. I'll let you know what
>happens when I try to deliver the sludge to a toxic disposal service.
>
>Kent
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>
Did some research and some calculations. The amount of dichromate that
is required to coat a piece of paper large enough for an 11x14 print
is approx .5 gram, when mixed with distilled water based on
the formula I used. Since part of it goes into the reaction with light
and the gum arabic/watercolor pigment to make the print, the residue is
small- less than .5 gram per coating. Putting together a pound of the
stuff, much less 50 as Luis mentioned (and that would be bad stuff
indeed) would require over 900 prints! Nothing I've read indicated that
diluting the stuff isn't ok for the home darkroom processor, and in fact
no other method of disposal is suggested.
If I'm missing something, tell me.
Gini