On Thu, 2003-06-12 at 12:06, EATON,JOHN (HP-Vancouver,ex1) wrote: > I hope he tells us how he disposes of all the used > chemicals. > > John Eaton For small scale uses of plating baths like sulfuric/copper or hcl/copper, it's possible to be environment considerate if you are careful. The thing to avoid is releasing dilute metal solutions into creeks...(or down the drain into your local treatment and river)...very bad. First of all avoid dilution! minimize washing -- squeegee first and run the wash runoff into some rock dust or baking soda. When your etching/plating baths get unusable, the conscientious thing is to reverse plate out the metal onto some junk, then you can concentrate the remains by evaporation, and use it as decorative coloring for rock or other metal sculpture projects...if that's not your hobby, you could also remove and drastically lower toxicity of acid metal solutions by filtering through some limestone cutting leftovers from your local garden wall and rock wall builders sawing operations -- the calcium carbonate rock dust goes into reaction with the metal to make a green compound called copper carbonate, (whaddaya know..), which is no big environmental hazard -- especially if you live in moutnains with green rocks : -> The acid gets neutralized by the limestone and CO2 is released. Fairly pure water is left. Just don't put any lead or tin in the same plating bath! Tin I don't know how to handle -- it's used for cooking pans, so not toxic itself, but may interfere with getting copper out of solution if mixed in with it.... Also it pays to research the know methods and see that HCl seems to be best utilized by industry for continous process plating -- it's a reverible process -- cleanable, rechargeable, etc. Reversibility means you can etch, and then plate, and minimize environmental impact that way. None of this is for the faint of heart, and I have not started it yet myself. Another etch process with sodium perchlorate sounds good. Its spent bath woudl have lots of copper chloride, so it may be possible to plate as HCl/Cu bath with the spent bath from perchlorate etching as a starting point. All of this needs a little storage and processing building with nothing but plating stuff and lots of open trays of baking soda around on the shelves and in the air flows.
John Griessen EE, sculptor
