Jon Pacini on fri 8 mar 02
Greetings all-----
Bill Arnold wrote.--------"Take a small amount of clay and make a bar that
will fit into a Dawson kiln sitter. Install in the kiln sitter and put a
full range to cones in kiln.Fire kiln. Inspect cones. Do not fire clay above
cone that is bent.''
The above is an interesting test. At many mines the raw clays are tested
for their PCE, Pyrometric Cone Equivalent.
In that test, the clay to be tested is made into the size and shape of a
standard Orton Cone and put into a holder with an array of standard cones.
The array is placed in a test kiln in a manner where the test cone can be
seen through the peep hole. The kiln is then fired and when the test cone is
bent over to a nice inverted U shape, the firing is halted. After the kiln
is cool, the array of cones is compared to the test cone and the one that
matches the inverted U is the designated PCE.
Jon Pacini
Clay Manager
Laguna Clay Co
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