[Clayart] Homemade Cone 5 and 6

David Hendley farmpots at eastex.net
Sun Apr 10 01:55:38 UTC 2022

On 4/8/2022 12:16 PM, ran mcc wrote:
> Does anyone have a recipe for homemade cone 5 and 6 cones?

Randy, I formulated recipes for homemade cones about 20 years ago. I 
could make
accurate cones (tested by firing along side commercial Orton cones).
One point to remember: Size of the cone is important. I made plaster 
molds from
Orton cones for mine. If your comes are smaller they will bend too early and
verse visa.

Since I fire at cone 10, I have good recipes for cones 8, 9, and 10. 
But, I think
you could interpolate from them to make cone 5 and 6 cones.
The basic idea in this temperature range is that, in the formula, SiO2 
is approximately
equal to the cone number and Al2O3 is approximately 10% of the SiO2.

So, my cone 8 is:
CaO  .68
MgO  .02
K2O  .22
Na2O  .09
Al2O3  .84
SiO2  8.41

The recipe is:
Custer feldspar  25.27
whiting  9.39
OM#4 ball clay  27.04
silica  38.31

Cone 10 is:
CaO  .67
MgO  .03
K2O  .21
Na2O  .08
Al2O3  1.25
Si02  10.02

So, to formulate cone 5 and/or 6, start with the formula and set the 
alumina and
silica in relationship to the cone number.
I don't think it matters too much which fluxes are involved. I simply 
used the
same four ingredients, feldspar, whiting, ball clay, and silica, for all 
the cone
numbers, and they determined the combination of fluxes.

May I ask why you want to do this?
I did it just to see if I could, and to get a better understanding about 
and they way they work.
You aren't fearing a zombie apocalypse where commercial cones will be 
are you?

David Hendley
david at farmpots.com

More information about the Clayart mailing list