Chris Schafale on sat 5 dec 98
Hi folks --
As I start testing/developing glazes, I've run into a problem. The
glazes I'm using so far (Floating Blue, and two color variations of
Tony Hansen's glossy cone 6 base) are tending to crack and flake off
as they dry, especially where there is an overlap of two layers.
Sometimes the cracks are small and the problems fairly minimal,
one other time I got my brand-new kiln shelves baptized with lot
of little glossy blobs which would have looked much better on
those bare spot on the side of the bowl....
Both glazes tend to "gel" rather dramatically and go on very thick
and uneven/gloppy if mixed with about equal parts by weight of glaze
and water, so I've added more water to get them thin enough to allow
a more even coat. Now I seem to be getting more cracking and
flaking, which I guess makes sense -- more water, more shrinkage.
I should mention that I'm applying the glaze as I learned to do at
the community arts center, where the glazes are mostly mixed quite
thin, requiring a 4-6 second dip for good coverage. For pitchers,
vases, etc, I'm pouring the inside, drying until I can put my hand
inside without marring the glaze, then dipping the outside, followed
by a final dip on the rim. (I use glaze tongs as little as
possible, since I always seem to get unattractive dots where the
tongs were). When I use this method with the very thick glaze
slurry, I get way too much glaze; when I thin the glaze, I get more
cracking as it dries. I've tried applying the second layer when the
first is as wet as possible, and also tried waiting until it is
drier, and I think I'm having just as much problem either way.
My question is, is there anything I can do to make these glazes
apply better, short of reformulating, calcining some of the
kaolin, or other solutions which require dumping out the buckets I've
already mixed and starting over? Would a higher bisque firing help?
If the problem is over-flocculation (caused by too much Gerstley
Borate in one case, and lots of EPK in the other), would one ever add
a tiny amount of deflocculant? How about the CMC or Veegum products
-- would they address this problem?
Or could it be my water?
Thanks for any help.
Chris
Light One Candle Pottery
Fuquay-Varina, NC
candle@nuteknet.com
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