peasley on thu 11 oct 01
I just had Clay Art Center in Tacoma make me up a batch of an old glaze I
found, called Mocha Matte. It has manganese in it, and am wondering of it is
food safe. They say it is, but I don’t have the formula, and am wondering of
any of you glaze guru’s out there can give me the word……I haven’t done the
lemon slice or vinegar test on anything – just got a couple of test pieces
out the other day, and the part with the Matte on it is along the edge and
side of the bowls.
Thanks in advance,
Pam in Seattle
Cindy Strnad on fri 12 oct 01
Dear Pam,
Manganese in your glaze won't make you sick, even
if it leaches out--unless you breathe it while
you're firing. Airways are the endangered species
here.
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
cindy@earthen-vessels-pottery.com
http://www.earthen-vessels-pottery.com
Earl Brunner on fri 12 oct 01
It looks like you are mixing up magnesium (see subject spelling) and=20
manganese ( see body of your message). This sometimes happens, and is=20
understandable, but is never-the-less confusing.
I infer from the body of your message that it is probably manganese that=20
you are talking about. If it is, you would probably have to do a leach=20
test to know if there were any problems. It is difficult to help much=20
without enough information.
As someone else has said on the list in the last few days, Manganese=20
seems to be mainly dangerous when inhaled in fume or dust form. In=20
other words it is probably more of a danger to the potter and people in=20
the studio than it is in the fired product. There has been a lot=20
discussed on this, but not much conclusive evidence given. The general=20
position has been that to be responsible, we should err on the side of=20
caution.
peasley wrote:
> I just had Clay Art Center in Tacoma make me up a batch of an old glaze=
I
> found, called Mocha Matte. It has manganese in it, and am wondering of =
it is
> food safe. They say it is, but I don=92t have the formula, and am wonde=
ring of
> any of you glaze guru=92s out there can give me the word=85=85I haven=92=
t done the
> lemon slice or vinegar test on anything =96 just got a couple of test p=
ieces
> out the other day, and the part with the Matte on it is along the edge =
and
> side of the bowls.
>=20
> Thanks in advance,
>=20
> Pam in Seattle
>=20
> _______________________________________________________________________=
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> Send postings to clayart@lsv.ceramics.org
>=20
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>=20
> Moderator of the list is Mel Jacobson who may be reached at melpots@pcl=
ink.com.
--=20
Earl Brunner
http://coyote.accessnv.com/bruec/
bruec@anv.net
Ron Roy on tue 16 oct 01
Hi Pam,
It is my understanding that Manganese is not a problem for the user - but
can be a serious problem for the maker - dust and firing fumes.
On the other hand - if the glaze is unstable enough to change colour in use
it will not be the best of situations. Matte glazes are seldome stable and
you should think twice about putting them on food bearing surfaces.
RR
>I just had Clay Art Center in Tacoma make me up a batch of an old glaze I
>found, called Mocha Matte. It has manganese in it, and am wondering of it i=
s
>food safe. They say it is, but I don=EDt have the formula, and am wondering=
of
>any of you glaze guru=EDs out there can give me the word=D6=D6I haven=EDt=
done the
>lemon slice or vinegar test on anything =F1 just got a couple of test piece=
s
>out the other day, and the part with the Matte on it is along the edge and
>side of the bowls.
>
>Thanks in advance,
>
>Pam in Seattle
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
=46ax 613-475-3513
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