Dave Finkelnburg on sat 30 jun 01
Martin and all,
I have followed this thread and stayed out for one reason. People will
do what people will do. You asked, so I'll answer, here's what I do.
I collect, as well as possible, all my waste glaze including that rinsed
out of sponges, off of screens, tools, etc. The nasties in it are primarily
a small amount of cobalt, copper and chrome. I mix it up and prefer to use
it as a liner glaze for large planters, etc. Since it isn't filled with a
bunch of lead or lithium, and I tend to use mostly glossy glazes, it fires
to pretty fair glass and I don't worry about it leaching.
I figure firing the scrap glaze this way is much better than dumping it
raw. I know other ClayArters feel the same way and fire their scrap glaze
into glass before disposing of it. If my scrap bucket gets too full, that's
how I intend to deal with it.
You are right, Martin, that dumping glaze waste in the trash just puts
the problem onto someone else. I do not think it is a good idea to pour the
raw oxides, carbonates, sulfates, etc. of heavy metals out on the ground,
whether driveway or garden. If it were industrial ground, that would be a
mini-Superfund site here in the U.S., and with good reason. Encapsulating
the waste in aluminum silicate glass in the kiln seems to me like a good way
to handle it.
Note I am talking about heavy metals. If the waste is only silica,
clay, feldspar, limestone, talc or iron, that can be disposed of anywhere
you like. It is the waste contaminated with colorant oxides which I worry