iandol on sun 27 aug 00
This is often referred to as Standard Cone 8. It is a glaze with a long =
history. Information I received some years ago was that it is the =
mixture of ingredients for Segar Cone 8 cones. Makes sense that it forms =
a glaze at cone 10. The earliest reference I can find in the literature =
is in B. Leach, A Potter=92s Book, first published in 1940. He calls it =
Cone 8 Limestone Glaze, p 172 in my reprint.
It is one of the most ubiquitous set of proportions in the Stoneware =
glaze database. Possibly the most messed about with as well. Tweaked, =
prodded, poked and pinched to make it work around the World on any clay =
and in any firing with any fuel and to give any colour or texture. If =
anyone wishes to survey all the recipe books for stoneware glazes they =
will find it is the foundation of some eighty percent of recipes of cone =
8 and upwards, give or take a percent here and a percent there with =
newly favoured ingredients. Which tells us how much need there is for =
designers of original glazes.=20
Long live the Stewards of Empiricism.
Ivor Lewis=20
John Hesselberth on fri 1 sep 00
iandol wrote:
>This is often referred to as Standard Cone 8. It is a glaze with a long
>history. Information I received some years ago was that it is the mixture
>of ingredients for Segar Cone 8 cones.
Hello Ivor,
The original recipe for Seger Cone 8 was a little different. From
Seger's paper titled "Pyrometers and the Measurement of High Temperature.
Standard Cones" he gives the recipe and unity formula for Standard Cone 8
as follows:
Feldspar 83.55
Marble 35.00
Quartz 156.00
Zettlitz Kaolin 64.75
0.3 K2O
0.7 CaO
0.8 Al2O3
8.0 SiO2
John Hesselberth
Frog Pond Pottery
P.O. Box 88
Pocopson, PA 19366 USA
EMail: john@frogpondpottery.com web site: http://www.frogpondpottery.com
"It is, perhaps, still necessary to say that the very best glazes cannot
conceal badly shaped pots..." David Green, Pottery Glazes
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