Re: I have a question
On Fri, 19 Oct 2007, Marilyn Dalrymple wrote:
The chemical that worries me most is the formaldehyde used for hardening the paper when doing the gum prints.For what it's worth I mention that formaldehyde has an extremely long working life so that as a practical matter there's much less of it to ultimately dispose of. For instance one teacher/ expert/printer (I forget whether Sarah Van Keuren or Jill Enfield, maybe both !) says she never dumps her formaldehyde hardening bath, just from time to time adds fresh solution as it diminishes. It kind of gets a "mellow" look, she says, but doesn't stain the paper and lasts more or less forever.
I myself switched to glyoxal, because I couldn't tolerate the formaldehyde in close quarters... The glyoxal is the opposite of formaldehyde in that the working solution breaks down in just one day. I admit it never occurred to me that it shouldn't be simply discarded down the drain, and I wonder if it's OK because it DOES break down so quickly?
On the other hand, with chemicals I know are bad, I get them concentrated (as for instance using a "first tray" for gum development until it's practically as thick as molasses, then putting it in the back yard with a screen over it until it dries, & disposing of it as solid waste), tho on the 3rd or maybe it's 4th hand, someone (Mike Ware?) said dichromate that's been oxidized and washed (or like that) is a tri, not a di, and not bad. (I may have the terms wrong, but I do recall the principle .)