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ash glaze quandary-specific density

updated fri 16 nov 07


Tom at on thu 15 nov 07

First suggestion Paul, would be, before adding water, check the specific
density of the glaze. When you first mixed the glaze, you should take a
known volume and weigh it. take the same volume of water and weigh it.
divide the weight of the glaze slop by the weight of the water...the result,
probably in the neighborhood of 1.5 or 1.6, is the specific density of your
Now, when you open the bucket and it seems much thicker, you take this
measurement again. If it is higher, then yes, you lost water somehow. My
bet is the weight is about the same, it just seems thicker. One of the
ingredient has flocculated the slop. I would guess the unwashed ash. Bases
flocculate, acids deflocculated.
At this point your correction is a deflocculant, not more water. If you
glaze with the watered down version, it will probably change your result
from first use, if you apply the glaze the same way.

I'll be interested in Ron R's take.

Tom Wirt

From: "Paul Steege"
=Subject: ash glaze quandary

I A month after mixing them, I went to glaze some pots and found that the
green glaze had not changed significantly in terms of how thick it applied
to the bisque, but the blue glaze required an addition of about a gallon and
a half of water (to a full five gallon batch) in order to get the right
thickness. Two days later I went to glaze some more pieces and found it
thickened again. I had to add two more quarts of water to get it the right
thickness. Now it takes forever to dry on my pots. Why such a difference
in consistency between the two glazes? What can be done to correct the
thickening issue?