This is nice to know and I have read it before - I believe one of the issues
with copper in a glaze is that it is one of the ingredients that leaches
very readily so if you are not getting significant amounts of copper
leaching from your pots that have a high amount of copper in the glaze (4%)
then you can feel secure that the base glaze is stable. However, what is
'significant' The question being posed here is what are the limits of
leaching for a standard of 'food safe'. As I said I don't think there is
any consensus on what is 'food safe'.

I believe the only standards in this regard that you find listed in this
country (U.S.A.) are for Lead and Cadmium (if I did not mention that... bad
on my part).

If you leave a lemon slice on a pot overnight and the color changes, this is
not a good glaze to use period. It is not a matter of 'food safe' - it is a
matter of quality. Who wants a pot that you think of as lasting over life
times that is going to be ruined the first time it is used with an acid base
food. Who wants to drink their orange juice, lemonaid or margarita and have
it ruined by a metallic taste.

"Lee In Mashiko, Japan" wrote in message
...
On Sep 11, 7:21 pm, "dkat" wrote:


John and Ron suggest using EPA standards for water (note that cobalt,
copper
and lithium are not listed by the EPA).

Copper is an essential nutrient that is become less available in our
modern food because it is being leached out of our soil by pesticides
and fertilizers. Amounts released by well made glazes are less than
dietary requirements.

The original concerns about copper was related to lead glazes
where poorly formulated copper glazes helps lead be more soluble.

In India, the switch from copper and brass water containers for
plastic is causing problems with water safety. Plastic contained
water depends upon sunlight to keep it from going foul.

--
Lee in Minneapolis.