Lead-free pottery, and how to know

Why lead is in pottery at all

Not as an additive and not as a shortcut — as chemistry. Lead has been used in ceramic glazes for centuries because it works unusually well: it gives a smooth, glass-like finish at a lower firing temperature, it lets bright colors and patterns underneath show through, and it keeps moisture out of the body of the piece. California's health department sets this out plainly, and it is worth understanding, because the point is not that some potters are careless. The point is that lead glazes are genuinely good at being glazes, which is why the practice persisted long enough to need regulating.

Modern US studio potters overwhelmingly use lead-free glazes, and the commercial glazes they buy are formulated that way. The risk concentrates somewhere else: in older pieces made before the rules, in imported traditional ware, and in anything decorative that has been re-listed as something to eat off.

The limits, and the detail nobody expects

FDA sets action levels for how much lead may leach out of ceramicware, measured by filling or soaking the piece in a weak acid solution and testing what comes off. The levels are not one number. They vary by what the piece is, and the logic is exposure: the longer and hotter a liquid sits against a surface, the more lead comes out of it, so the categories that hold hot drinks are held to the tightest limit.

A mug is held to a limit six times stricter than a plate. That is the single most useful fact in this subject, because it tells you where to direct your attention: if you are going to be careful about one piece in a cupboard, be careful about the thing you drink coffee and tea out of every morning, not the dinner service. Ceramicware that exceeds the FDA levels cannot legally be sold in the US.

What lead-free legally means, and what it does not

Two terms get used interchangeably and they are not the same. Lead-free means the ware contains no lead. Lead-safe means it contains some lead, but not enough leaches out to exceed the limits. California's health department draws exactly that distinction, and it is the reason a listing that says lead-safe is not hedging — it is being precise.

FDA has also been explicit about the label itself: ceramicware that contains extractable lead when tested by the prescribed method should not be labelled Lead Free, and doing so can constitute misbranding. That guidance was issued after FDA received reports of traditional pottery imported from several Mexican manufacturers, labelled Lead Free, that in fact contained extractable lead at levels comparable to those found in lead-glazed pottery. The practical consequence for a buyer: the words on the box are a claim, not a test result, and they are worth more when the maker is identifiable and worth less when they are not.

What to look for in a listing

You cannot tell whether a piece contains lead by looking at it — that is the first thing California's guidance says, and it is true. What you can do is read the risk factors, which are well established, and read the listing for the claims a real maker volunteers.

• A stated food-safe or lead-free glaze. Any potter selling functional ware will say this, because it is the claim that matters to their customers. Silence is not proof of a problem, but it is a reason to ask.
• A named maker, studio or state. Accountability is the strongest available signal when you cannot hold the object. How to tell handmade pottery covers the other provenance tells.
• Functional, not decorative. Decorative ware may use glazes never tested for food contact, and a decorative piece re-listed as a serving dish is a real category on marketplaces. If the listing hedges, treat it as decorative.
• Decoration under the glaze, not on top of it. Run a finger over the pattern. If you can feel it, or see brush strokes standing above the glazed surface, the decoration sits on top — which is where lead-containing decoration is found.
• Nothing bright on the food-bearing surface. Including the upper rim of a cup, which is in contact with a mouth. Plain white ware rarely contains lead at all.

The pieces to be careful with

This is where an honest handmade-goods site has to be straight with its readers: California's health department lists home-made and hand-crafted tableware, from the US or abroad, among the categories to be careful with unless you are sure the maker uses a lead-free glaze. We are not going to leave that out. It belongs alongside the other high-risk categories, which are consistent across every public-health source: rustic glazed terra cotta from some Latin American traditions, such as Mexican bean pots, where the guidance is to stop cooking in them at once unless they are labelled lead-free or sin plomo; highly decorated traditional ware from some Asian communities; and antique tableware handed down, or bought at flea markets and estate sales, which predates the regulations entirely.

There is also one condition that is a stop sign rather than a caution. A corroded glaze, or a dusty chalky gray residue left on the glaze after washing, may represent a serious lead hazard, and a piece in that state should not be used. That is a visible, checkable thing, and it is the one case where you can act on appearance alone.

Three habits that reduce the risk on anything uncertain

1. Do not heat food in it. Cooking and microwaving speed up leaching. If you are unsure about a piece, it is a serving dish and not a cooking one.
2. Do not store food in it. The longer food is in contact with the surface, the more lead is drawn out. An unknown bowl is for the hour of the meal, not for the fridge overnight.
3. Keep acidic food out of it. Citrus, apples, tomatoes, soy sauce, salad dressing, fruit juice, cola, coffee, tea, wine. Acid pulls lead out far faster than neutral food does, which is why rice, potatoes, water and milk are the safe things to put in an uncertain dish.

Any two of those stacked together is worse than either alone — storing tomato sauce in a questionable dish and then microwaving it in the same dish is the example California's guidance itself uses. One more practical note: if a piece does contain lead, a dishwasher can damage the glazed surface and make it leach more next time, and in some cases lead may contaminate other items in the load. That is one of several reasons unknown and antique ware should be hand washed, and handmade pottery care covers the rest of the dishwasher question per glaze.