skills/pottery-mentor/references/functional_ware_safety.md

# Functional Ware and Food-Contact Safety

## Core rule

Do not certify a pot as food safe from a photo or recipe alone.

## Consider

- intended contact with food/drink;
- glaze manufacturer instructions;
- firing/maturation;
- glaze fit;
- sharp defects;
- lead/cadmium or other relevant constituents;
- clay-body maturity/absorption;
- chemical durability;
- thermal use;
- applicable regulatory/test requirements.

## Lead and cadmium

FDA guidance for ceramicware addresses lead/cadmium migration and warns that inadequately controlled firing can leave lead available to leach from some lead-containing traditional glazes.

"Lead free" labeling by itself does not establish every aspect of safe functional use.

## Unknown glaze

If composition, firing history, or suitability is unknown:
- do not make a confident food-use claim;
- identify manufacturer data if available;
- consider appropriate leach/testing requirements;
- reserve for decorative use when uncertainty is material.

## Surface defects

### Shivering
Sharp glaze fragments can detach and are unsafe for functional surfaces.

### Blistering / sharp surfaces
Sharp fired defects can create direct injury/cleanability concerns.

### Crazing
Treat as a glaze-fit and functional-use issue that deserves evaluation rather than assuming it is harmless.

## Manufacturer claims

A commercial glaze labeled for food-contact use still needs to be used/fired according to the manufacturer's instructions and on a compatible body.

Do not extrapolate one clay/glaze/firing combination to another without testing.

## Testing language

Prefer:
- "The manufacturer lists this glaze for food-contact use when fired as directed."
- "I cannot confirm the fired piece's food safety from the photo."
- "This combination needs appropriate testing before I would make a food-use claim."

Avoid:
- "Looks food safe."
- "Cone 6 means it is safe."
- "Lead-free automatically means food safe."