How to clean cast iron grates without ruining them

Seasoning versus build-up

Seasoning is a thin, smooth, evenly black layer of polymerised oil bonded to the iron — it is the non-stick surface and you want to keep it. Build-up is thick, uneven, flaky and often sticky or shiny in patches. It traps old fat, smokes, and tastes of last summer.

The goal of cleaning cast iron is to remove the second without stripping the first. Aggressive abrasion cannot tell them apart; a chemical degreaser plus a soft brush largely can.

Step by step

1. 1

   Cool the grates completely

   Cast iron holds heat far longer than it looks. Wait until it is genuinely cool to the touch, then brush off ash and loose flakes with a soft grill brush.

2. 2

   Foam both sides

   Lift the grates out if you can and coat top and bottom. Grease collects underneath where you can't see it.

3. 3

   Let it dwell, then work the texture

   Two to five minutes depending on build-up, then use a soft-bristle or nylon brush along the bars — not a steel wire wheel.

4. 4

   Rinse, dry immediately, re-oil

   Rinse with clean water, dry at once with a towel (bare iron rusts within minutes), then wipe a thin film of high-smoke-point oil over the surface and heat the grill for 10–15 minutes to set it.

What to avoid

• Soaking cast iron in water — it rusts, quickly and deeply.
• Dishwashers, which strip seasoning and leave the iron bare.
• Steel wire wheels and angle grinders, which remove seasoning and can leave bristle fragments behind.
• Putting grates away damp; always dry and oil first.
• Pressure washing, which strips seasoning and drives water into the grill body.

Keeping them clean between deep cleans

• Burn off at high heat for 10 minutes after cooking, then brush while warm.
• Wipe a light coat of oil onto the bars before each cook.
• Deep clean with degreaser once a month in season.
• Store the grill covered and dry through the off-season.