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 skillets — 8-inch (20 cm), 9.5-inch (24 cm), and 11-inch (28 cm) — and a stainless steel lunch box 3-pack, 27 oz (800 ml) each. Every product is made from 100% 304 (18/8) food-grade stainless steel, without synthetic coatings, and made without intentionally added PFAS.

The skillets' 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 Warranty.

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 nanometers thick. This layer separates the steel from whatever touches it and re-forms on its own if the surface is scratched or polished.

Nickel stabilizes 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 silverware.

• 18% chromium — reacts with oxygen to form the passive layer that makes the steel stainless
• 8% nickel — stabilizes 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 nonstick 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 skillet 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 skillets?

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 skillet 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: 100% 304 (18/8) food-grade 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. Our 304 stainless steel holds third-party food-contact test certification — independent laboratory verification that the material meets food-contact standards.

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

What is California Proposition 65?

Proposition 65 — formally the Safe Drinking Water and Toxic Enforcement Act of 1986 — is a California right-to-know law. It requires businesses to notify Californians about potential exposure to substances on a state-maintained list. The list is long, covers many substances found in everyday products and foods, and California sets its own intentionally conservative warning thresholds.

Because the thresholds are conservative, Proposition 65 warnings appear on a wide range of ordinary household products. A warning is a disclosure required by California law. We treat it the way we treat every materials question: follow the rule, show the information, and let you read it in context.

Where a Proposition 65 warning applies to a specific product, it appears on that product's packaging and Amazon listing.