Cast Iron: Seasoning & Care
Updated August 15, 2026
Seasoning is oil polymerized into a hard, slick coating by heat: rub the pan with a whisper-thin layer of neutral oil, wipe it until it looks dry, and bake upside-down at 450–500°F for an hour. Day to day, just cook, wash (yes, soap is fine), dry on the burner, and wipe with a drop of oil.
The soap myth, retired
Seasoning isn't a film of grease soap can wash away — it's polymerized oil, chemically bonded plastic-hard to the iron. Modern dish soap won't touch it. What actually damages seasoning: long soaks (rust), the dishwasher (rust, always), scouring with bare steel wool down to metal, and long-simmered acidic sauces, which soften seasoning and pick up metallic flavor. Tomato sauce gets the Dutch oven; steaks get the cast iron.
The routine, and the rescue
After cooking: wash warm with a brush, dry immediately on a low burner until water's gone (air-drying is how rust starts), then rub in half a teaspoon of oil with a paper towel until the pan looks dry, not greasy. That 90-second ritual is 95% of cast-iron ownership — every cook adds a micro-layer of seasoning, which is why old pans are slick.
Rusty pan: scrub the rust off with steel wool or a half-potato and coarse salt, wash, dry hot, and re-season with 2–3 thin oven cycles. Thin is the law — a thick oil coat bakes into sticky varnish that has to come back off. Cast iron is nearly unkillable; every thrift-store crust hides a good pan.
Quick answers
- Can I use soap on cast iron?
- Yes — modern dish soap is mild and can't remove polymerized seasoning. The real enemies are soaking, the dishwasher, and being put away wet.
- What oil is best for seasoning?
- Any neutral high-smoke-point oil: grapeseed, canola, vegetable. Flaxseed builds a famously hard layer that's also famously prone to flaking. Thinness matters more than the oil.
- Why is my cast iron sticky?
- Too much oil, baked too cool — it varnished instead of polymerizing. Bake it hard at 450–500°F to finish the cure, or scrub back and re-season thin.