Copper does not necessarily cause glazes to leach if used in moderate amounts

These are four cone 6 glazes of diverse chemistry. They have varying melt fluidities. They are soaked (halfway up) in lemon juice overnight. None show any evidence of surface changes. All contain 2% copper carbonate. If the copper was increased, especially to the point of going metallic or crystallizing, the leaching test would produce different results (especially on the ones that are running, they lack SiO₂ and Al₂O₃). So, if you use copper sensibly (in moderate amounts), there is a good chance of making a glaze that resists leaching.

Videos

Links

Glossary	Leaching Ceramic glazes can leach heavy metals into food and drink. This subject is not complex, there are many things anyone can do to deal with this issue
Glossary	Food Safe Be skeptical of claims of food safety from potters who cannot explain or demonstrate why. Investigate the basis of manufacturer claims and labelling and the actual use to which their products are put.
Oxides	CuO - Cupric Oxide
Hazards	Copper Oxide and Carbonate

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