Re: cleaning up after gum...
On Thu, 21 May 2009, Paul Viapiano wrote: Paul, this is a subject on which no easy answer has appeared IME. But I'll give you two items from my experience: First, when I was teaching "alt" at Pratt, someone new in the chem department began a purity kick. Coming around to our lab, he decreed that all dichromate wash water had to be collected and saved to give to some department or other that would -- whatever they did, render it, or purify, or something. I said, are you kidding? I can't get these kids to just empty a tray, no matter how I smack them. But he was adamant. I said I wouldn't teach the course under those conditions, but the next day I got on the phone -- and after a couple of hours got through to someone who identified himself as "Captain" someone or other of the EPA. After I explained the problem, he asked me, "How much ammonium dichromate do you use?" I thought a minute, then guessed that, "My students and I probably use about a pound a year." He laughed, and said, "We're concerned with air conditioners that use a pound & 3/4 a month (or like that). This is not a problem." I reported this to the chem department & heard no more. The other item came also years ago (offlist, as I recall) from Mike Ware. He explained that dichromates in the water stream quickly change from chrome one (or whatever it was) to something or other two. He used the chemical terms which I didn't know then, and know even less now, but explained that the 2nd form was harmless. That combined with the fact that in NYC probably 100 toilets are flushing every second to dilute effluent further, is also probably relevant, tho I imagine that if your waste is going into your own septic tank, you might not want the paint to go in there more than you didn't want the dichromate. I myself, when I first began gum, sequestered all wash water in a tray, let solids sink to the bottom, then poured off the (relatively) clear top water and disposed of the gunky part as solid waste. But the fact is that watercolor painters (for instance) don't do any such thing, and the paint (especially cadmium colors) can, I understand, be far worse. In any event, so much water goes down the drain from just our apartment, let alone the other 7 in the house, and the amounts of dichromate I use are actually quite small, and I NEVER was one to waste paint, I relaxed, and let it flow. Judy I have a question concerning cleaning up properly...
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