Why your griddle seasoning is flaking off

First: it is not rust

Rust is orange-brown and sits in or on the metal. Flaking seasoning is black and comes off in sheets or chips, often revealing darker, sound seasoning or gray metal underneath.

They have different causes and different fixes, and treating one as the other wastes an afternoon. If yours is orange, go to rust removal instead.

The cause, every time

Coats applied too thickly to polymerize properly.

A seasoning coat has to be a molecular film for the whole thickness to cross-link. When a coat is thick enough to see as a layer, the top carbonizes while the bottom stays soft and tacky. You have built a layer that was never bonded all the way through.

Add a few more cycles on top and you have a stack of partially-set layers with weak interfaces. Heat cycling expands and contracts the plate, the weak layer eventually lets go, and a sheet lifts.

That is why flaking usually appears months after the mistake that caused it, which is why people rarely connect the two.

Why adding more oil makes it worse

The instinct is to re-season over the flaking. That adds another layer on top of an unstable stack — the weak interface underneath is still there, and now it is carrying more weight.

You have to take the loose material off first.

The fix

1. Heat the griddle gently — warm, not hot.
2. Scrape firmly across the flaking areas with a stiff flat scraper. Loose material comes off readily; that is what makes it loose.
3. Work back to a sound layer. Keep going until what remains does not lift under the scraper. You are not necessarily going to bare metal — you are going to whatever is properly bonded.
4. Use a pumice block or heavy pad on stubborn edges where flakes are partly attached. These edges will lift later if you leave them.
5. Flush the debris out of the grease channel and drain. Flakes and grit end up there and come back into food otherwise.
6. Wipe clean, then re-season with properly thin coats. Thin enough that the surface looks almost dry. The process.

Partial flaking is fine to treat partially

If only one area is affected, you do not need to strip the whole plate. Take that area back, blend into the surrounding sound seasoning, and re-season the area. The color will be uneven for a while and it will even out with use.

Not to do it again

• Every coat thin enough to look almost dry after wiping back. If it looks wet, it is too thick.
• Heat until the smoking stops, every round. Pulling early leaves an unset layer. Why that signal works.
• Do not re-season a griddle that is cooking fine. More layers is not better. How often you actually need to.
• Use squeeze bottles so you dose a thin line rather than a puddle.

One more cause worth mentioning

Some oils polymerize into a notably hard, brittle layer — flaxseed is the common culprit. Hard and brittle on a large plate that thermal-cycles and gets scraped is a recipe for chipping. Oils compared.