Many, Many years ago I found out that one should not fire green ware and
glazed peices in the same load. I think the gases escaping from the
greenware
mess up the glaze on the other peices. Well, several of my seventh graders
clay head sculptures had bumps and bubbles all over them, much like a case
of adolescent zits. We entered three of the heads in Scholastics and all
three were
given awards by the judges. We learned again, that art is a lot about
accidents.
Kids do love clay. It's a headache for teachers but they need to have
the kids
work with it.
Woody in KC