not throw as high as previously (particularly if there is vibration in the
wheel), bulbous shapes crack in the belly before the clay gets leather
hard and leaning figures crack and fall down, etc. It is caused by
soluble alkali components (e.g., Frit or Nepheline Syenite) in the clay
slowly dissolving and attacking the ability of the clay particles to hold
together. The remedy (never perfect, but this will buy time) is to add
about 0. 25% of Calcium Chloride or Magnesium Sulphate to the water in
the clay before mixing. This should increase the time that the batch
will remain workable. The exact percentage of the acid substances
necessary for each clay body can be determined by experiment. Once
the deflocculation exists in a batch of plastic clay the only answer is

to dry the clay out completely and then add the acid substances to the
water used to slake the clay down again.

It is easier to deal with deflocculation in glazes. When a glaze settles
quickly after stirring, it is probably being affected by deflocculation -
particularly if the settled glaze forms a hard and heavily-settled layer
at the bottom of the pail. One remedy is to add the previously noted
approximately 0.25% of acid substances. [f the effect seems to wear off,
then more can be added, but eventually, a point will be reached when

the acids have no more effect and then it is worthwhile to consider the
follav ing points:

I, If the glaze is in a metal container move it into a plastic one.
The electrical conductivity of plastic is less and as these effects
are due to electrolysis their manifestation is less when in an
insulating container.

2. Calculate your glaze back to a unity formula and see if you can
substitute less soluble constituents for soluble ones.

3. Consider other physical properties of glaze materials. Cole-
manite, for instance, is an excellent suspender as it forms a
gelinwater. [f 2-5% can be added to your formula in some way
this will help. Keep the clay content as high as possible so that
the “floccing" effect (which works mainly on the clay) will be
most pronounced.