Kollin Baker on wed 25 mar 98
Manager at Armidillo clay gave me this simple recipe for Cornwall Stone. I
tested it in 3 diffrent glazes each ^6 and on diffrent types of clay, all
worked well to very well.
Anyway here is the substition if anyone saves these messages for later
referance.
Silica/flint 22
EPK 11
C. Feldspar 67
mix dry and measure appr. amount into glaze formula.
KBaker
Pi Pottery and Design
512.323.8274
David Hewitt on fri 27 mar 98
Out of interest I ran this out on my Glaze Calulator to see if I came up
with the same recipe alternative for Cornish Stone. The siica came out
at 11.16 (see analysis below) which strust me as rather high. I suppose
it all depends on the formulae that you use for your raw materials, but
for interest these are the figures that I would use.
Cornwall Stone
K2O .29 Al2O3 1.16 SiO2 9.0
Na2O .44 Fe2O3 0.01 TiO2 0.01
CaO .27 P2O5 0.03
Using my raw material data for Custer Feldspar I would come up with the
following alternative recipe
Custer Feldspar 61.3
EPK 12.9
Silica/flint 22.6
Whiting 3.2
This has the analysis of :-
K2O .514 Al2O3 1.16 SiO2 9.0
Na2O .221 Fe2O3 0.01 P2O3 0.02
CaO .27
MgO .003
Cornwall stone is of course a somewhat variable material, so perhaps
others use a different analysis and so either of these may work out OK
for someone. They are certainly both quite close.
In message , Kollin Baker writes
>----------------------------Original message----------------------------
>Manager at Armidillo clay gave me this simple recipe for Cornwall Stone. I
>tested it in 3 diffrent glazes each ^6 and on diffrent types of clay, all
>worked well to very well.
>
>Anyway here is the substition if anyone saves these messages for later
>referance.
>
>Silica/flint 22
>EPK 11
>C. Feldspar 67
Using my raw material data, the analysis for this is:-
K2O .67 Al2O3 1.41 SiO2 11.16
Na2O .29 Fe2O3 .01
CaO .04
MgO .00
>
>mix dry and measure appr. amount into glaze formula.
>KBaker
>
>
>Pi Pottery and Design
>512.323.8274
>
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP6 1DQ, UK. Tel:- +44 (0) 1633 420647
Own Web site http://www.dhpot.demon.co.uk
IMC Web site http://digitalfire.com/education/people/hewitt.htm
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