LEDINGHAMS on tue 30 apr 96
Does anyone out there knows the US equivalent for British frit Potterycraft
#2955 or the chemical composition? you can e-mail me at LEDINGHAMS@SIAST.SK.CA
Thank you in advance.
David Hewitt on thu 2 may 96
The Potterycrafts catalogue gives the following analysis for P2955
Borax Frit MW 234.7
0.417 Na2O
0.214 K2O
0.366 CaO
0.002 MgO
1.205 Al2O3
1.884 SiO2
0.425 B2O3
I know the basic oxides add up to 0.999, but that is what the catalogue
says.
I do not know which US frit would make the best match, but perhaps this
information will help you find one. It is likely that you will not find
an exact fit, in which case you will need to adjust the recipe to take
this into account (I assume that your query results from a recipe which
you are trying to use). The important oxide in the frit is the B2O3. If
you can use a US frit which will give you the amount you require you can
achieve the other oxides by altering the amount of such materials as
china clay, whiting etc to achieve the same analysis as the recipe which
you are trying to replicate.
David Hewitt
David Hewitt Pottery Caerleon, Newport, Gwent, UK.
Tom Buck on thu 2 may 96
Adding to David H's post of the Seger of P-C's Frit 2955. Frank Harmer,
in his article "The Potter's Friend" (Ceramic Review #146, 1994), lists
2955 as a Borax Frit "GP Alkaline", gives its melting range as 920-1050
deg Celsius and cites its expansion level as "high". He also notes only
one other frit (also British) that matches its Seger.
I believe that David's approach will provide a workable solution
to the Clayarter who wants a substitute, namely, choose an alkaline frit
that contains some B2O3, and modify some other ingredients to bring about
the effect of 2955. It is easy to do on a computer. Either I or David
could probably do it if the glaze recipe were sent to us. Cheers TomB
Hamilton Canada
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