LEAD AND OTHER HEAVY-METAL
GLAZE SOLUBILITY

In response to some recent queries on the above
subject, the following ts a procedure for determining
the existence and solubility of heavy-metals in glazes,
This ts a reprint of information made available by the
Canadian Guild of Potters in March 1970, in an article
by Gordon Barnes, their Research Chairman. A full
copy of the article is in the Guild office.

Most concerns are with low fire functional ware from
places such as Mexico or China. While lead begins to
volatize at Cone 5, this test may be a good indicator of
the presence of other heavy metals as well.

Materials:
4 oz. white vinegar
|/8 tsp. Liver of Sulphate (also known as Sul-
phated Potash or Potassium Sulphide)
2 clear glasses, sarne shape and size.

Procedure:

1 Put 2 ozs. of vinegar in the test pot and soak at
room temperature for 12 hours.

2. Dissolve the Liver of Sulphur in 2 ozs. hot water.

3. Place the test vinegar in one glass and an equal
amount of fresh vinegar in the other glass.

4. Put 2 tsp of the sulphur solution in each glass,

5. Awhite cloudy percipitate will form in the fresh
vinegar.

6. If the test vinegar percipitate is tinged tan or
brown, there are heavy metals present and the
glazes deserve more accurate analysis before us-
ing on the inside of any container.

“Frad-Up: Contemporary Works in Clay” will be naving t& Fitn Annual
Exhibiion and Sale on May 27th and 28h, Dam. to Spam, at the Metehosin
Communty Hall, Yictora. information (804) 474, 2897 evenings

Sculptural ceramic workshop ny Chuck Wiesingeron June ardand 4m, Victona, BC.
Canada, © am to 4pm, fee $40, students #20 Sponsored by “Fired-isy

infomation (60474-2897 evenings.
Arlene Yarned

Co-Ordinator

GREENBARN
POTTERS SUPPLY LTD.

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Some pottery suppliers seem to be having
difficulties these days. We intend to be around
for quite a while yet, and want to thank
everyone for their continuing support as well
as to reassure you that we intend to be here
to supply your needs for clay, materials, tools,
and equipment, for years to come.

to improve and broaden our service to the
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EASTER HOURS: aay
Closed: Friday March 24th rit
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Sunday, 26th

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Monday, 27th

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SPINA SEMINAR ™
The seminar is on again this year!

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more details soon,

April 29th in Namaimo. We will have

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FAP SP LP

9548-192nd St. Surrey
Phone: 888-3411

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