douglas adams on sat 17 jul 99
Hi all! I have read in" Crystalliane Glazes" by Diane Creber, that
using a leaded firt 'renders the lead non-lechable and safe to use for
commercial application' (pg 36). Does this mean it is food safe and can be
used on mugs and plates, or does it mean the potter will not get lead
poisioning while using the glaze?
Anyone who could clairify this for me, I would appreciate your help. Thanks
again.
Ron Roy on mon 19 jul 99
Not true - never will be - when a lead glaze is melted - regardless of
where the lead came from - it can still release lead into foods. What
determins the durability of a glaze has to do with it's resistance to acid
and alkalie attack - not which frit it happens to have started with.
Diane has been reading too many pottery books written by those who should
know better.
RR
>----------------------------Original message----------------------------
> Hi all! I have read in" Crystalliane Glazes" by Diane Creber, that
>using a leaded firt 'renders the lead non-lechable and safe to use for
>commercial application' (pg 36). Does this mean it is food safe and can be
>used on mugs and plates, or does it mean the potter will not get lead
>poisioning while using the glaze?
>Anyone who could clairify this for me, I would appreciate your help. Thanks
>again.
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
Tom Buck on tue 20 jul 99
This business of fritted lead glazes and food-safety has regularly been
chewed over on Clayart. If you went to the Clayart archives you would
discover that the general consensus is
1) lead-containing glazes should not be considered food safe
without actual proper leach tests being performed; and
2) too many base glaze mixes in the literature make lousy
glass, and lousy glass means lead release to food.
So, the best advice is to avoid the use of lead, fritted or
otherwise, in any glaze used on a pot that could end up holding say orange
juice, or a salad doused with oil/vinegar.
Tom Buck ) tel: 905-389-2339
(westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street,
Hamilton ON L8T 3E1 Canada
John Hesselberth on tue 20 jul 99
douglas adams wrote:
>----------------------------Original message----------------------------
> Hi all! I have read in" Crystalliane Glazes" by Diane Creber, that
>using a leaded firt 'renders the lead non-lechable and safe to use for
>commercial application' (pg 36). Does this mean it is food safe and can be
>used on mugs and plates, or does it mean the potter will not get lead
>poisioning while using the glaze?
>Anyone who could clairify this for me, I would appreciate your help. Thanks
>again.
Hi Douglas,
This statement is just plain wrong--it was made by someone who apparently
doesn't understand the technology and is a good example of why you
shouldn't believe everything that gets printed in a book. Using lead in
fritted form has no effect on leaching--leaching is determined by overall
glaze composition and firing conditions. The only way to know if a
lead-containing glaze meets federal or state standards for use with food
is to have it tested by a professional testing lab. Further you must
test often to make sure that small changes in firing conditions or glaze
composition don't affect the leaching.
We've covered this subject many times on ClayArt and I think I can
summarize by saying most studio potters have no business using lead
containing glazes on functional work. We don't have the necessary
control of our processes nor the necessary access to testing of our
product to assure its safe use.
Using lead in fritted form does make it somewhat safer for the potter to
handle.
John Hesselberth
Frog Pond Pottery
P.O. Box 88
Pocopson, PA 19366 USA
EMail: john@frogpondpottery.com web site: http://www.frogpondpottery.com
"It is time for potters to claim their proper field. Pottery in its pure
form relies neither on sculptural additions nor on pictorial decorations.
but on the counterpoint of form, design, colour, texture and the quality
of the material, all directed to a function." Michael Cardew in "Pioneer
Pottery"
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