Paul Taylor on thu 21 dec 00
Dear Craig and any one interested
The test came out
100 norfeld plus 2.5% iron sulphate A crazed shino gray white with The
iron soaking into the porcelain and giving a brown line on the rim there was
something nice about the effect.
I knew that the 100% norfeld would do that or something similar although I
would have thought for the iron staining to be more red either the wandering
habits of soluble iron building up too much concentration or the sulphur was
not reduced out of it.
85 norfeld and 15 whiting came out an olive green and the iron had moved
to give some strange brown marks at the bottom of the pot.
I am wondering if the extra iron that is in this glaze made a big
difference are we Talking .1 % in accuracy for iron in the blue glazes- the
whiting turned the iron sulphate yellow .
I think the test confirms that my whiting has too much contaminate in. but
I will do the test again with out so much iron
85 norfeld 15 wolistonite- out came a blue green celadon. There was
either too much iron or my wolistonite also contains too much titanium. I
think the latter.
The kiln was a little over fired orton nine down I will do all thes tests at
cone six to seven Orton
Of course I could be reducing at the wrong time I will put in test rings
to test when the glaze fluxes I am guessing about 1160 c but I am still
reducing all the way .68 Mv + on the probe.
I also notice that the soluble iron spread is more brown than red I shall
make up a grelog porcelain to be sure to be sure:) of maybe that the sulphur
having an effect.
Regards from Paul Taylor
http://www.anu.ie/westportpottery
Ps Thanks for the shinos post. I will set the conversion equations up on the
spread sheet I have got so used to reading glaze formulas percentage wise.
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