How cast iron cookware is made
Skillets, Dutch ovens, griddles, grill pans, kadais, dosa tawas and paniyaram pans are poured in sand moulds. Molten grey iron fills a cavity formed from a pattern; when it cools the sand is knocked out and the casting is fettled, which means the gates and fins are cut off and the edges ground. Some makers machine or grind the cooking surface smooth; others leave the as-cast texture.
Then the piece is cleaned by shot blasting and either pre-seasoned, with a thin layer of vegetable oil baked on in an oven until it polymerises into a dark coating, or enamelled, which brings in the checks on our enamelware page. Some traditional tawas get only an oil wipe against rust.
Sand casting leaves its own faults: gas holes, sand trapped in the surface, cold shuts where two streams of iron did not fuse, and cracks if a casting cools unevenly. A crack in a pan can be invisible until heat opens it. Cast iron household articles that are not enamelled (HS 7323 91) were a small export line at US$15.84 million in FY2025-26 (TradeStat, provisional). We have found no official source naming a cast iron cookware cluster, so we name no town.
What we check on cast iron cookware
| Check | How it is checked | What fails |
|---|---|---|
| Cracks | Piece hung by the handle and tapped (ring test); surface examined, especially at handle roots and spouts | Dull, dead sound instead of a ring; visible hairline crack |
| Porosity and blowholes | Cooking surface, walls and underside checked under raking light | Holes, pits, cold shut lines, especially on the cooking surface |
| Sand inclusions | Surface checked and scraped lightly with a fingernail | Sand grains embedded in or under the seasoning |
| Base flatness | Pan on a flat glass plate; feeler gauge under the edge | Rocking, a raised centre, a gap beyond your tolerance |
| Seasoning coverage and cure | Surface checked for bare grey patches; touched for tackiness; rubbed with a paper towel | Sticky or tacky surface, runs and drips, flaking, brown residue on the towel |
| Rust | All surfaces checked, including inside handles and lid rims | Orange spots, rust under seasoning |
| Weight and wall thickness | Each sampled piece weighed against the sample; wall measured at the rim | Outside the weight tolerance; thin spots |
| Fettling and edges | Hand run along rims, handles and the base | Sharp fins, grinding gouges, rough edges |
| Lids and markings | Lid fit rotated; cast-in logo and size marks read | Rocking lid, blurred or wrong cast marks |
Common cast iron cookware defects and how they are classed
| Defect | Typical cause | Class |
|---|---|---|
| Crack in body, handle root or spout | Uneven cooling, knock-out damage | Critical: can fail with hot food or oil in it |
| Hole through a wall | Gas porosity or shrinkage | Critical |
| Sticky or tacky seasoning | Too much oil, under-baked | Major |
| Seasoning flaking | Oil on a dirty or wet surface, too thick a coat | Major |
| Rust spots | Bare spots in seasoning, packed damp, humid storage | Major |
| Base rocking | Warped casting, pattern wear | Major |
| Sand inclusion on cooking surface | Poor mould sand, inadequate blasting | Major |
| Sharp fins or grinding marks off the cooking surface | Rushed fettling | Minor if not sharp; major if they can cut |
Your defect list decides the final class.
Market rules for cast iron cookware
- EU. Regulation (EC) 1935/2004 Article 3 covers the iron and the seasoning. The seasoning oil should be a food-grade vegetable oil, documented by the factory. Germany's LFGB is often named in purchase orders; there is no LFGB certificate. See EU 1935/2004 and LFGB.
- US. FDA has no approval for finished cookware. Any coating or oil on the food surface must be suitable for food contact, and FDA states that no regulation authorizes lead as a cookware component. Castings poured from mixed scrap are where buyers ask for lead tests. See FDA food contact.
- California. Enamelled cast iron and painted exteriors can raise lead or cadmium under Prop 65.
- Performance and claims. Induction, oven-safe and "pre-seasoned, ready to use" claims on the box should match what was tested. EN 12983-1 covers hob cookware of any metal and is a common buyer reference.
- Labels. Care instructions matter more than on any other pan: hand wash, dry, oil. Missing care cards are a common major finding.
Packing, transit and your purchase order
Cast iron rusts quickly in a humid container, and a pan that leaves the factory dry can arrive spotted. Pieces should be fully dry and cool before packing, wrapped in rust-inhibiting (VCI) paper or a film where agreed, with desiccant in the carton. They are heavy, so cartons need double walls, corner protection and the right stacking limit; a skillet handle can punch through a weak carton. The inspector checks dryness, wrapping, carton weight and a drop test where agreed, and notes storage conditions in the warehouse.
Put these in your purchase order:
- Iron grade and weight per piece, with tolerance.
- Cooking surface: as-cast or machined smooth.
- Seasoning oil, number of coats and cure; "no sticky surface" as a stated requirement.
- Base flatness tolerance and induction claim.
- Rust protection: VCI paper, desiccant, maximum days between packing and loading.
- Care card wording and cast-in marks.
For coated aluminium pans, see aluminium and non-stick cookware.
Sources
- Regulation (EC) No 1935/2004 on food contact materials (EUR-Lex)
- FDA: Warning about imported cookware that may leach lead (August 2025)
- BSI: EN 12983-1, Cookware for use on top of a stove, cooker or hob, general requirements
- Department of Commerce, TradeStat: commodity-wise exports (HS 732391, FY2025-26 provisional)