mel jacobson on tue 24 jul 07
it is always fun to read old recipes/as in leach.
`add 28 percent water ground quartz.`
i thought in 1959...`where can i get water ground quartz?`
as fred has pointed out.
we now use silica. that is what comes from the catalog.
silica is quartz is flint.
it came in a variety of purity.
we now have pretty much a standard product. 325 mesh silica.
i still have a bag marked `flint`.
in the old days i found out that whiting was calcium carbonate.
you could buy a bag at minnesota paint for a buck.
same bag as sold at minnesota clay. sort of like buying bananas
at the farmers market. they all come from costa rica, not a garden in
willmar, minnesota.
those were fun days...looking for stuff, finding it in strange
places....that is how we learned about ceramic chemicals.
then rhodes wrote his book...`clay and glazes for the potter`.
it was an epiphany.
for those that want to learn, today is better. not so much
mystery. a million sources of information. i love looking in hamer and hamer.
mel
from: mel/minnetonka.mn.usa
website: http://www.visi.com/~melpots/
Clayart page link: http://www.visi.com/~melpots/clayart.html
Jeremy Harper on wed 25 jul 07
Hiya Clayart. Just found the site, and after readng this I thought it was
best if I registered.
<> This is not correct.
Silica is a group of minerals that includes many forms of SiO2. Some
examples are quartz, cristobalite and tridymite. So quartz is just one type
of silica.
Flint is sedimentary rock found associated with calcium rich rocks such as
limestone. The genesis of flint is not fully agreed but it is generally
believed to be linked to ancient crustaceans - flint may be fossils! Flint
is rich in silica, but it is not the same as silica. It has been the
traditional filler used in England for pottery, and it is still used a
little. Before use flint is calcined to high temperature, and aftewards
primarily consists of quartz and cristobalite.
Also there are many different particle size grades of flint and quartz
other than 325 mesh. And wet milled grades are available.
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