I just got home from helping a Art Teacher clean out an old cupboard.
In it was a square piece of - what I imagine is - slate. The box
was marked Borax Slate… It is about 5" square with a circular
indentation( not that deep but that wide ) about 4" in the middle.
Any ideas on what it is for and how it is used… Also we threw out
buckets of old casting sand that smelled horrible and asbestos
soldering pads, so that shows you how old this stuff was. I couldn’t
find it in the Rio Catalog, so hoped that some of you may have an
idea. I hate to throw out anything that MIGHT SOME DAY be
Thanks in advance.