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kaolin and eutectics -- tom wirt's question

updated wed 7 mar 01


Dave Finkelnburg on tue 6 mar 01

Hello Tom!
You asked if finer kaolin "....would give better particle distribution
>maybe lower the eutectic. It seemed to have some effect in making the
>glaze smoother...."
Significantly finer particles will always melt somewhat sooner than
coarser particles of the same materials. This is likely what you observed.
Think of your kaolin particles as ice cubes tossed into a glass of warm
soda. The soda is way above the melting point of the ice, but the ice still
takes times to melt. The smallest ice melts fastest, just like your finer
kaolin in the glaze.
This is also why ball milling can cause a glaze to melt better. Of
course, one has to remember that excessive ball milling can ruin the
application properties of a glaze! :-(
Strictly speaking, what you observed probably should not be confused
with a eutectic. A eutectic can be defined as a chemical composition with
the lowest possible melting point of all the possible compositions of
mixtures of the chemicals involved. In theory, you didn't really change the
chemical composition of your glaze, or if you did, probably not by much.
Good glazing!
Dave Finkelnburg in suddenly spring-warm Idaho