iandol on fri 25 apr 03
Dear Lois,=20
If it is your intention to continue with Cone 10 flat to the floorboards =
with this glaze:
Felspar-(Custer) 51.0, Silica 21.0, Whiting-(vicron) 13.0
Gerstley borate 6.0, Soda ash 4.0, Barium carb 4.0
Lithium carb 1.0,=20
I suggest your stiffen it up a bit by excluding the low temperature =
melting fluxes. So leave out the Gerstley Borate and the Soda Ash. To =
help improve the viscosity and reduce flow even further I would bring =
the recipe back up to 100% by adding 10% Kaolin. At Cone 10, this should =
dissolve into the melt and not alter the other qualities of your glaze.
Best regards,
Ivor
John Britt on sat 26 apr 03
Lois,
This glaze is called Karen's Starshine and is listed in Val Cushing's
Handbook. (Calls for Titanium 2% also). This is essentially a copper red
base and is probably meant to be fired to cone 9 or a partically bent cone
10.
If you exchange the gerstley borate and soda ash for kaolin you will
definitely change the character of the glaze.
I would try to stiffen the glaze a cone or two by doing a Currie blend.
That is, add kaolin and silica. If you don't want to do the whole blend,
you could start by adding 1 % of silica and 1 % of kaolin and test, then 2
% etc. until you test about 10% additions.
Hope that helps,
John Britt
iandol on sun 27 apr 03
<<definitely change the character of the glaze.>>>
Dear John Britt,=20
I substituted the Kaolin to keep the round numbers. There appeared to be =
sufficient melting flux to provide solvent power to dissolve that =
quantity. It could be omitted and made up to a value or 90 parts. Adding =
more silica might cause precipitation of Wollastonite and that would =
change the character of the glaze. A person could employ Ian's grid =
method if they had the information.
Best regards,
Ivor
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