What "Food Safe Glaze" Actually Means — And Why It Matters More Than You Think
If you use handmade ceramics for eating and drinking, you have probably seen the term "food safe glaze" on a piece of pottery. It sounds reassuring. It is meant to. But the gap between what that phrase implies and what it actually guarantees is significant — and worth understanding.
This article explains what Swiss and European law actually requires, what it doesn't cover, and why testing matters beyond legal compliance.
What the law says — and what it doesn't
In Switzerland, ceramic tableware is regulated under legislation aligned with the European Directive 84/500/EEC. This directive establishes migration limits for two metals: lead and cadmium.
That's it. Two elements, out of dozens that can be present in ceramic glazes.
For those two metals, specific maximum levels apply depending on the type of object — a cup, a flat plate, a large bowl. If a piece respects those limits, it can be sold legally. If a manufacturer labels a ready-to-use industrial glaze as "food safe", it means those two elements are within legal limits.
Nothing more.
No legal migration limit exists in Switzerland for: cobalt, arsenic, barium, chromium, boron, mercury, lithium, rubidium, selenium, strontium, nickel or zinc — among others.
These elements are present in many commercial glazes. They can migrate into food and drink in contact with ceramic surfaces, particularly when that contact involves acidic foods such as vinegar, tomatoes, citrus, wine or coffee. And because no legal limit has been set for them, there is no requirement to test, disclose or restrict their migration.
Why do different countries test different things?
The variation across Europe is striking. As Joëlle Swanet — one of the leading specialists in ceramic glaze chemistry in the French-speaking world — has documented in her research: Belgium tests lead and cadmium only. France adds cobalt, aluminium and arsenic. Austria includes antimony, zinc and barium. Finland monitors chromium and nickel. The Netherlands maintains the most comprehensive list, covering cobalt, arsenic, barium, chromium, boron, mercury, lithium, rubidium, selenium and strontium, in addition to lead and cadmium.
The same glaze. The same cup. Different levels of protection depending on where you happen to live.
This inconsistency reflects an ongoing regulatory process rather than a scientific consensus that the unlisted elements are safe. The European Commission has been working toward a revised directive for over a decade, with proposals to expand the list of tested elements significantly. As of now, however, the revision has not been finalised.
The problem with "food safe" industrial glazes
When a ceramist purchases a ready-to-use industrial glaze labelled "food safe", they are working with a product that has been formulated to stay within the lead and cadmium limits required by law. That is a genuine guarantee — and it is not nothing.
But it does not mean the glaze has been tested for arsenic migration. Or boron. Or nickel. Or zinc. The label addresses what the law asks for. The law asks for very little.
This is not a criticism of manufacturers. It is simply a description of what legal compliance currently means in this context.
What independent testing actually involves
A comprehensive glaze migration test goes well beyond the legal minimum. The standard process involves immersing a glazed ceramic sample in a 4% acetic acid solution — which simulates acidic food contact — at room temperature for 24 hours. The solution is then analysed using ICP-MS (inductively coupled plasma mass spectrometry), a highly sensitive method capable of detecting trace quantities of numerous elements.
A full test of this kind analyses migration across 27 or more elements simultaneously — not just two. If the result shows zero detectable migration for all tested elements, that is a meaningfully different claim from "within legal limits for lead and cadmium."
Why the current legal limits are also outdated
There is a further complication. The migration limits established for lead and cadmium in the 1984 directive have not been updated to reflect current toxicological understanding. The German Federal Institute for Risk Assessment (BfR) noted as early as 2005 that the existing legal limits for lead could be exceeded while still remaining technically compliant — and that the limits should be reduced by a factor of up to 400 to reflect what is now considered acceptable exposure.
The limits have not been changed.
This means that a ceramic piece can respect current law and still release amounts of lead or cadmium that modern health science would consider inappropriate for regular daily use.
Why formulating from raw materials changes everything
This is precisely why I formulate every glaze at Clay & Tao from raw materials — and why the chemistry training I received from Joëlle and Eric Swanet matters so much in this context. A glaze is glass. When the chemical formula is unstable, the glass will deteriorate progressively over time — even if it appears solid straight out of the kiln. With each use, each acidic contact, each thermal cycle, the surface degrades a little further. Migration does not happen all at once: it accumulates, slowly and invisibly, over months and years of regular use.
Knowing how glaze chemistry actually works — the interactions between oxides, the proportions that create stability, the behaviour of a formula at temperature — makes it possible to formulate a glaze whose structure is so robust that nothing migrates, regardless of what elements are present in the composition. The goal is not to avoid certain elements. It is to ensure that the glass formed in the kiln is completely sealed, and remains so for the lifetime of the piece.
Every glaze at Clay & Tao is independently tested for 27 elements. Not to verify that migration stays within legal limits — but to confirm that there is none.
Lead · Cadmium · Mercury · Arsenic · Antimony · Barium · Beryllium · Bismuth · Boron · Chromium · Cobalt · Copper · Nickel · Zinc · Tin · Aluminium · Iron · Manganese · Molybdenum · Selenium · Strontium · Vanadium · Titanium · Thallium · Uranium · Silver · Gold · Lithium · Rubidium · Caesium
What this means in practice
If you use handmade ceramics regularly — for your morning coffee, for cooking, for daily meals — it is reasonable to want to know what has been tested and what hasn't. A few questions worth asking:
Has the glaze been tested by an independent laboratory?
How many elements were tested?
Were the results zero migration, or within legal limits?
Does the ceramist know the composition of their glazes?
These are not alarmist questions. They are the kind of questions a careful consumer might reasonably ask about any material that comes into regular contact with food.
Sources
European Commission — Revision of EU Rules on Food Contact Materials (ceramic and vitreous FCMs) food.ec.europa.eu/food-safety/chemical-safety/food-contact-materials/revision-eu-rules_en
EUR-Lex — Summary of Council Directive 84/500/EEC on ceramic articles in contact with foodstuffs eur-lex.europa.eu/EN/legal-content/summary/ceramic-objects-in-contact-with-foodstuffs.html
European Parliament — Parliamentary Question E-10-2025-000380 on lead and cadmium in ceramics, glass and enamelled tableware (2025) europarl.europa.eu/doceo/document/E-10-2025-000380_EN.html
German Federal Institute for Risk Assessment (BfR) — Opinion No. 043/2020: Ceramic crockery — BfR recommends lower release of lead and cadmium bfr.bund.de/cm/349/ceramic-crockery-bfr-recommends-lower-release-of-lead-and-cadmium.pdf
German Federal Institute for Risk Assessment (BfR) — Opinion No. 023/2005: Lead and cadmium from ceramics bfr.bund.de/cm/349/lead_and_cadmium_from_ceramics.pdf
Benelux Union — Official Bulletin 2024/2: Decision on migration limits for lead and cadmium in ceramic food contact materials benelux.int/wp-content/uploads/2024/12/Bulletin-2024-2-FR.pdf
Swiss Federal Food Safety and Veterinary Office (OSAV/BLV) — Tableware and kitchen utensils blv.admin.ch/blv/fr/home/gebrauchsgegenstaende/materialien-in-kontakt-mit-lebensmitteln/geschirr-und-kuechenutensilien.html
Clay & Tao glazes are tested by an independent laboratory for 27 elements. Results are available on request.
