Is earthenware safe to cook in

Zlakusa pottery has no glaze. The question of lead and cadmium, rightly asked of glazed ceramics, therefore does not apply to it: there is no coating in the vessel for anything to pass from into the food — only a fired mixture of clay and calcite. Two real questions remain: what the porous wall does, and what the vessel is washed with.

Where the lead question comes from

Lead compounds were used for centuries as a flux in glazes fired at lower temperatures: they lower the melting point and give a bright, smooth layer. In a properly formulated and fully fired glaze the lead stays bound in the glassy mass. The trouble starts when a glaze is poorly formulated or underfired — then lead can pass into food, most readily into acidic food such as vinegar, lemon, tomato or wine, and the faster the hotter the dish and the longer it stands in the vessel.

So the question is rightly asked of glazed ware of unknown origin, and above all of decorative, hand-painted pieces never made for food in the first place, though they easily end up as a bowl in a kitchen. On an unglazed vessel that path simply does not exist, because there is no glaze.

What the regulations require

Ceramics intended for contact with food are not an unregulated field. In the European Union the limits on lead and cadmium passing from ceramic articles into food are set by Directive 84/500/EEC, as amended by Directive 2005/31/EC, which divides articles into three groups by shape and purpose — flatware, hollowware, and cookware together with larger storage vessels — with its own limit for each. Serbian rules on articles of general use impose the same kind of requirement.

For a buyer it comes down to two things visible to the eye: the glass-and-fork symbol on the product or its packaging, meaning the article is intended for contact with food, and the declaration of compliance a seller provides on request. A piece with neither is not necessarily dangerous, but nobody has claimed it is for food.

The unglazed vessel and its porous wall

All an unglazed vessel has is the material it is made of — clay and ground calcite, fired on an open fire. A porous wall gives nothing off into the food, but it takes up whatever reaches it, and that is the reason for the one serious rule of care: no detergent. Detergent stays in the wall and the next cooking returns it to the food. Fat from the seasoning stays in the wall in just the same way — only there it is wanted.

The second consequence of porosity is moisture. A vessel put away before it has dried completely can pick up a stale smell, and in time mould — that is the real hygienic risk with this kind of ware, not the material.

• No detergent and no dishwasher — the wall takes up both
• Dry it completely before putting it away, as a rule overnight
• Acidic dishes are cooked in it, but not stored in it for days
• Keep the sponge dedicated, for the pottery alone

If you already own glazed ware

Not every glaze is suspect — the great majority of ware sold through ordinary retail in Europe carries a declaration and stays within the limits. Caution belongs to pieces with no marking at all: souvenirs from a trip, old pieces of unknown origin, hand-painted ceramics bought as an ornament. Such a piece should not be used to store acidic food for long, nor for dishes that sit hot in it for hours; for dry things and for serving there is no objection. If the glaze has crazed into a network of fine lines or is flaking, the vessel is no longer for food whatever its origin.

Zlakusa pottery

unglazed — no glaze, and so no lead in a glaze

Composition

clay and ground calcite, roughly 1:1, fired on an open fire

Risk with glazed ceramics

a poorly formulated or underfired glaze, mostly with acidic food

EU regulation

Directive 84/500/EEC, as amended by 2005/31/EC

What a buyer looks for

the glass-and-fork symbol and a declaration of compliance

Real risk with unglazed ware

detergent in the wall and moisture at storage