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gerstley borate solubility

updated fri 3 may 02


George Mackie on sun 19 jan 97

This form of colemanite is rather soluble and consequently
affects the viscosity of glaze slurries containing a lot of it. If
Lithium carbonate is also present in the mixture, crystals appear over
time. To get around borate solubility, you could try substituting
a frit like 3211 which is very like colemanite.

Dave Finkelnburg on wed 1 may 02

Amen, Earl!
Solubility of gerstley borate is one of the reasons GB causes glazes to
gel. That can be good for suspension if the glaze only gels a little, or
bad, if it gels a lot. Depends on how much GB you use and how long the
glaze sits.
Of course, GB solubility is very, very limited compared to solubility of
things like soda ash, borax, or alkalis in wood ash, but the effect is far
greater than if boron is sourced from a frit.
Good glazing,
Dave Finkelnburg

-----Original Message-----
From: Earl Brunner

>This is true in the general sense, however Gerstley Borate is not
>completely insoluble. It has been a fairly good source of boron for
>glazes that was cheaper than commercial frits. But solubility has been
>an issue with it.