Sometimes glaze flaking off is due to cooling too quickly, but more
likely, it is a problem with either being too thick, or the clay body
and glaze not shrinking at the same rate (one shrinks more than the
other), or greasy or dusty ware prior to glazing. It is more likely to
happen with underglazes, but i have had it happen with glaze, as well.
FRUSTRATING! ANd WHY is it that it is always the best pieces in the
kiln when it happens? Sometimes it could be some contaminant in the
clay body. It is most likely to happen on rims or edges. You should
always wash off bisque that has been sitting and gathering dust for a
long time before you glaze it. And you should always dampen clay that
you are going to underglaze before painting it. The porous damp clay is
more likely to suck the underglaze fully into the pores of the clay.
That may mean that the first coat is thinner than the rest, but that's
ok. I have also heard that some people water down their first coat a
bit more than teh next two, hoping that the underglaze will really soak
into the pores of the clay and not just be superficial. I feel your
Visit our student's web art gallery at St.John's School
click on "Stories of SJS," click on "Arts Stories," click on Linda
Woods' name. View artwork by Lower, and Middle School students as well
as our art archives.