Judy Musicant on sat 17 aug 02
Paul,
That's what I get for no glazing tech. knowledge! But are you also saying that Randy's Red with iron oxide would not be durable for food surfaces? That hasn't been my experience. Years of using Randy's Red lined mugs and bowls - leaving coffee and tea in them for hours; washing them in the dishwasher, and they look like new.
Judy
Original message: "Actually, Judy, I'd bet it wouldn't. These iron red recipes tend to be VERY
low in alumina. I have seen some analyses that, because of the particular
analysis of Gerstley Borate that that particular calculation database was
using, had a SiO2:Al2O3 ratio that was infinite. In their analysis, the
glaze had no Al2O3 whatsoever! Most software databases won't quite tell you
that, but all of these iron red recipes I've ever seen have very low alumina
levels and a ratio of 18:1 or more. Consequently, I wouldn't think they'd
be very durable for use as liner glazes. There are certainly far better
ones out there.
Paul Lewing, Seattle"
Paul Lewing on sun 18 aug 02
on 8/17/02 7:02 PM, Judy Musicant at huju01@COMCAST.NET wrote:
> That's what I get for no glazing tech. knowledge! But are you also saying
> that Randy's Red with iron oxide would not be durable for food surfaces? That
> hasn't been my experience. Years of using Randy's Red lined mugs and bowls -
> leaving coffee and tea in them for hours; washing them in the dishwasher, and
> they look like new.
They may look the same, but I'd sure have a glaze with that little alumina
tested before I'd use it as a liner glaze. Granted, if there are no
colorants in it, you're probably not going to leach anything harmful, but
you'll never know without professional lab testing.
Paul Lewing, Seattle
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