Materials & Safety: What SEIDO Cookware Is Made Of

What are SEIDO Cookware products made of?

The SEIDO Cookware range is deliberately simple: three uncoated stainless steel frying pans — 20 cm (8 in), 24 cm (9.5 in) and 28 cm (11 in) — and a stainless steel lunch box 3-pack, 800 ml (27 oz) each. Every product is made without synthetic coatings and without intentionally added PFAS: the frying pans are tri-ply clad, with a 304 (18/8) stainless steel cooking surface, and the lunch box containers are 304 (18/8) food-grade stainless steel.

The frying pans' cooking surface is bare 304 stainless steel — the same grade used across commercial kitchens and food processing equipment. The lunch boxes are built for adult routines — office, gym, commute and weekly meal prep — and are microwave-safe by design. Every product is backed by a 5-Year Limited Warranty (lunch box lid parts: 1 year).

What does 304 (18/8) stainless steel mean?

304 stainless steel is the standard food-contact grade of stainless steel. The designation 18/8 refers to its composition: roughly 18% chromium and 8% nickel, alloyed with iron. The two names describe the same material — 304 is the technical grade, 18/8 is the composition shorthand.

Chromium is what makes stainless steel stainless. At 18%, it reacts with oxygen to form a passive layer — an invisible, self-renewing film of chromium oxide only a few nanometres thick. This layer separates the steel from whatever touches it and re-forms on its own if the surface is scratched or polished.

Nickel stabilises the steel's structure and improves its corrosion resistance, which is why 18/8 is the standard for equipment that touches food: commercial kitchens, food processing lines and everyday cutlery.

• 18% chromium — reacts with oxygen to form the passive layer that makes the steel stainless
• 8% nickel — stabilises the alloy and adds corrosion resistance
• Iron — the balance of the alloy, with small, tightly controlled additions

Does stainless steel cookware contain PFAS?

PFAS (per- and polyfluoroalkyl substances) are a family of synthetic compounds used in many non-stick coatings. In cookware, PFAS are a coating question — they are associated with the applied layer, not with the metal beneath it.

Uncoated stainless steel has no coating to contain them. The cooking surface of a SEIDO Cookware frying pan is bare 304 (18/8) stainless steel, and SEIDO Cookware products are made without intentionally added PFAS and without synthetic coatings. For shoppers searching for cookware made without intentionally added PFAS, uncoated stainless steel is a direct answer: no applied layer, no place for coating chemistry to live.

Our wording is deliberate. 'Made without intentionally added PFAS' describes exactly what we control — our materials and our manufacturing process — without overstating what any manufacturer can measure to absolute zero. We hold precision in claims to the same standard as precision in products.

Why does SEIDO Cookware make uncoated frying pans?

A coated frying pan's performance depends on a layer applied to its surface — and that layer is the weak point. Coatings can scratch, flake and degrade with heat and use. When the coating goes, the pan goes with it.

An uncoated frying pan removes the problem instead of managing it. There is no applied layer, so there is no coating to flake into food, scratch off or degrade with normal use. The cooking surface is the material itself: 304 (18/8) stainless steel. Food release comes from technique — proper preheating and a little oil — not from a coating with a shelf life.

How does SEIDO Cookware verify its materials?

We publish what our products are made of, and we test it. The 304 stainless steel of our lunch box containers has been lab-tested for its total chromium content, and the report is published on this page.

We name the alloy, we state the composition, and we give measurements in plain units. Materials questions deserve materials answers.