jcjm on sat 4 mar 00
I was just wondering whether you could crush up a glazed, high fired piece
of clay, taking the energy involved as granted, and use it as a filler or
grog of some kind? Technically, would the glaze involved cause a problem
in the clay body?
Just wondering.
j-m
Nikom Chimnok on sun 5 mar 00
Once a Japanese artist told me that you should use no more than 10% glazed
pots when making grog. But that depends. Because of the flux in the glaze,
you're going to end up with a clay that has a lower maturing temperature
than straight clay. But not by much. Think of the percentages: How much does
the glaze weigh, compared to the clay? And how much of the glaze is flux,
compared to the silica/alumina content? The answer to both questions is:
Very little.
Because we fire tons and tons of large pieces, and use a very thin glaze, I
know that 20 kilos of glaze covers approximately 2500 kilos of clay. In
practical terms, the glaze in the grog seems to have no effect whatsoever,
even tho we're using 20% grog. We don't worry about it at all--if a glazed
piece is unsalable, it becomes grog.
Of course, we're using a red claybody and making brown glaze. The limit
would be much tighter if you were firing small pieces with thick glaze and
needed a pure white body--at some point you'd get discoloration, as well as
significantly lowering the maturing temperature of the body. Maybe that's
where the 10% figure comes from.
Nikom
**************************************************
At 19:10 4/3/00 EST, you wrote:
>----------------------------Original message----------------------------
>I was just wondering whether you could crush up a glazed, high fired piece
>of clay, taking the energy involved as granted, and use it as a filler or
>grog of some kind? Technically, would the glaze involved cause a problem
>in the clay body?
>Just wondering.
>j-m
>
>
ferenc jakab on sun 5 mar 00
As my commercial line is garden pots my wife gets all my seconds and the
drive way gets every thing else. We have about a kilometre of gravel drive.
So far the shards have had little visual impact.
Feri.
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