A dishwasher strips the seasoning off cast iron and leaves bare metal sitting wet for an hour. It will come out grey, sticky and starting to rust.
Cast iron works because of seasoning: thin layers of oil polymerised onto the metal. Dishwasher detergent is specifically designed to break down oil, and the dry cycle is nowhere near long enough to dry out a heavy pan. Those two facts together are why every cast iron maker says no.
| Short answer | Never, including enamelled with a bare rim |
|---|---|
| What it destroys | The seasoning layer, which is what makes it non-stick |
| What follows | Surface rust, usually within a day |
| Correct method | Hot water, stiff brush or chainmail, dry on the burner, light oil |
| Soap | Mild dish soap is fine, despite the myth. Dishwasher detergent is not. |
How to clean it properly
- Clean it while it is still warm, not cold the next morning.
- Hot water and a stiff brush or a chainmail scrubber. A little mild dish soap is fine.
- For stuck-on food, coarse salt as an abrasive beats any amount of soaking.
- Dry it immediately, then put it on a burner for a minute until no steam comes off.
- Wipe a thin film of neutral oil over the cooking surface while warm, then buff until it looks almost dry.
What happens when you get it wrong
- Grey, dull metal. That is the seasoning gone. The pan will stick at everything until you build it back up.
- Orange rust. Bare iron plus an hour of steam. It usually appears within a day.
- A rough, patchy surface. Partial stripping is harder to fix than full stripping, because the remaining layers are uneven.
- Enamelled pans. The enamel survives, but the bare rim and handle edges rust, and repeat cycles dull the finish.
A chainmail scrubber and a stiff brush handle anything a dishwasher would, in about ninety seconds.
If the seasoning is already gone, scrub it back to bare metal, oil it thinly and bake it upside down at 450F for an hour.
Frequently asked questions
Can you put cast iron in the dishwasher?
No. Dishwasher detergent is designed to break down oil, and seasoning is oil bonded to the metal. The pan comes out stripped, and an hour of steam with no seasoning left means rust.
What happens if you accidentally put cast iron in the dishwasher?
It is recoverable. Scrub off any rust with steel wool or coarse salt, wash and dry it completely, coat it thinly with neutral oil and bake it upside down at around 450F for an hour.
Can you use soap on cast iron?
Yes. The idea that soap ruins cast iron comes from the days when soap contained lye. Modern mild dish soap will not strip properly bonded seasoning. Dishwasher detergent is far harsher and will.
Is enamelled cast iron dishwasher safe?
Manufacturers often say yes, but repeated cycles dull the enamel and any bare rim or chip will rust. Hand washing keeps enamelled pans looking right for far longer.
How do you stop cast iron rusting after washing?
Dry it immediately and finish it on a hot burner until no steam comes off, then wipe a thin film of oil on the cooking surface while the pan is still warm.