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safety of glaze--semi rant for newbies

updated tue 13 jul 04


Lili Krakowski on mon 12 jul 04

Oh my dear! Oy, my dear!


Jacob writes:


" The pots I make turn out smooth and glossy so I assume they are =
non-porous, but I don't know if they are non-toxic (If it says they are =
non-toxic on the glaze container are they safe?"

Wouldn't that be dreamy? ! But it's like assuming -and that too =
would be so nice-that because someone is a great lover he will be a =
great husband!


Glazes-with some exceptions - that are shiny and glossy are shiny and =
glossy. That does NOT mean they are food safe (lead made some of the =
shiniest and glossiest of glazes), stable (lead, ditto) or non-porous =
(many crazes are invisible to the naked eye for a while-or why Hobart =
Cowles considered a strong magnifying glass and essential glaze making =
tool.) The container only tells you that there is nothing toxic in the =
glaze. Toxidity is NOT the only risk, and you can ruin the safety by =
adding, let us say, certain colorants.


Porosity is a function-by and large-of the BODY. Of the clay. Raku =
pots are porous, low fired ware is porous, and you get to non-porosity =
only at the higher ranges-our beloved c4-6 range generally offers some =
non porous bodies. =20

Visualize this: What you are doing is putting a yummy frosting on a =
half-baked cake. What you need to do is bake that cake. For a proper =
pot as for a proper cake you need both a good cake and a good frosting; =
a good clay and a good glaze ("good" here meaning appropriate.)

To try another image: as we see on TV, especially under "entertainment" =
a lot. We see absolutely beautiful young bodies dressed in what =
appears to be torn up underwear. We see diverse singers overweight and =
overage and dressed gorgeously. The same applies to clay and glaze. =
Great bodies, wretched glazes. Not so great bodies, fabulous glazes. =20

Can a truly porous body be used safely under a glaze that fits? In my =
opinion I'd rather not. It is fine, and correct to say that many people =
have used, do use, non-vitreous, quite porous pottery for food. One: =
many folk potters have no choice; even if they had "better" clay =
bodies, they would have to charge too much for the folk to pay. Two: =
their primary concern is to find food to go in the pot not to worry =
about the pot. Many of these folk still use lead utensils, drink =
polluted water, and on and on.. Sad reality but real.

Also: I always have had serious qualms about what bacteria may go into =
the porous ware from the food. Of course when the dog washes the dishes =
for you, or you use water from a polluted multi purpose stream etc.

I think anything that has to do with food should be immensely cleanable. =
Scrub scrub! Hot water. Strong soap. If necessary boiling =
water..(Remember: I grew up way before anti biotics came along. )=20


The argument that these people have done it forever does not hold water! =
People ate off lead glazed ware for forever too..

Last but not least. "Primitive" folk don't sue. We, as a culture, do =
a lot of suing. =20

I am concerned about what big stores sell. As I am concerned when =
magazines -including alas some clay mags-show markets in tourist places =
selling lovely pottery-and not a word about whether those glazes are =