Janet H Walker on wed 3 feb 99
...they sell Sheffield clay as a substitute for Albany clay
...Sorry not even close...
That's odd. According to the geology of the two areas, it should
actually be relatively close. What was I reading? Maybe Obstler's
Out of the Earth, Into the Fire. Sheffield MA and Albany NY are
pretty close to each other as the crow flies and their clays are
both from the same geological era (pre-Cambrian?)
As for Science, our pal David Hendley posted an Albany slip substitute
about ?a year ago? I don't know at this point whether it looks anythign
like Albany slip but it makes a pretty nice dark "slip glaze" all by
itself.
David's Albany Sub ^6
72 Red Art clay
8 Kona F-4 feldspar
10 whiting
5 EPK
5 talc
Hmm. I bet RR would say this is oversupplied in alumina. It doesn't
quite flux on most of the red clays i've tried it on. Two firings
helps it get a sheen.
Cheers,
Jan Walker
Cambridge MA USA
Richard Aerni on thu 4 feb 99
Well, they may be close to each other, and the rocks may be from the same
era, but the truth is in the firing. I've done a fair amount of testing
looking for Albany lookalikes, and Sheffield is not even close, at least
for my purposes. I fire in reduction to cone 10.
Sheffield, is significantly more refractory. I add 20% frit 3124 to it,
plus 10% whiting, and still do not get near the melt I would get with
Albany. I've got the Sheffield analysis around someplace, I will look it
up if you really want it, but they are not really interchangeable at cone
10. Alberta slip I use as a 1 to 1 sub and it has approximately the same
degree of melt and color. However, nothing really beats Albany slip, at
least in the way I use it. I finally decided to quit hoarding my last
150 lbs of it and now have it back in my glaze repertoire.
Good luck,
Richard Aerni
Bloomfield, NY
Janet H Walker wrote:
>
> ----------------------------Original message----------------------------
> ...they sell Sheffield clay as a substitute for Albany clay
> ...Sorry not even close...
>
> That's odd. According to the geology of the two areas, it should
> actually be relatively close. What was I reading? Maybe Obstler's
> Out of the Earth, Into the Fire. Sheffield MA and Albany NY are
> pretty close to each other as the crow flies and their clays are
> both from the same geological era (pre-Cambrian?)
>
>
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