David Hewitt on sat 13 jul 96
In the digest of 9th to 10th July I posted a recipe and analysis for a
transparent matt glaze at cone 8. In the same digest was a recipe for a
cone 5-6 transparent matt from Tony Hansen in response to the same
request.
I think it is interesting to compare the two analyses and see their
similarities, There is the obvious difference that only one contains
B2O3, the lower cone glaze, but there are also some general similarities
but from very different recipes. I think it is an interesting example
which shows the value of giving analyses, either as formula or % weight,
together with a recipe, wherever possible.
For easy reference and to illustrate the point I repeat the two recipes
and analyses below:-
Tony's Recipe My Recipe
CALCIUM ALUMINA TRANSPARENT MATTE CONE 5-6
RECIPE AMT OXIDE FORM ANAL ANAL FORM RECIPE AMT
------------------------------------------
WOLLASTONITE 30.00 CaO 0.90 19.35 12.07 .44 Cornwall
Stone 50
FERRO FRIT 3134 21.50 MgO 0.01 0.10 8.82 .45 EPK 22
KAOLIN 25.50 Na2O 0.10 2.29 1.77 .06 Dolomite23
K2O - - 2.38 .05 Whiting 6
CALCINED KAOLIN 19.00 TiO2 0.00 0.02 - - Talc 10
FLINT 4.00 B2O3 0.19 5.14 - - ---
Al2O3 0.51 19.94 17.58 .35 Total 111
SiO2 2.29 52.95 56.94 1.94
Fe2O3 0.00 0.17 0.29 -
MnO 0.00 0.04 - -
P2O5 - - 0.29 -
WEIGHT: 259.87 L.O.I 3.33
David Hewitt
David Hewitt Pottery Caerleon, Newport, Gwent, UK.
URL http://digitalfire.com/magic/hewitto.htm
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