Detergent strips the polish off copper and turns it dull brown within one cycle. On lined pans it also attacks the tin or the rivets, and that damage is not cosmetic.
Copper reacts with almost everything, which is why it conducts heat beautifully and why it needs looking after. Dishwasher detergent is strongly alkaline and oxidises the surface fast. The pan still cooks, but it will never look the same, and the lining underneath is the part that really matters.
| Short answer | Never, lined or unlined |
|---|---|
| First cycle damage | Dull brown oxidation across the whole surface |
| Lined pans | Tin lining can soften and pit; stainless linings survive better |
| Rivets and handles | Dissimilar metals corrode where they meet |
| Correct method | Warm soapy water, dry immediately, polish occasionally |
How to wash and restore copper
- Wash by hand in warm soapy water while the pan is still slightly warm.
- Dry immediately and thoroughly. Water spots on copper become tarnish.
- For tarnish, make a paste of equal parts salt, flour and white vinegar, rub it on, leave a minute, rinse and buff.
- Lemon half dipped in salt works for light tarnish and takes seconds.
- Never use abrasive pads, which leave permanent scratches in soft copper.
What happens when you get it wrong
- Dull brown, patchy surface. Oxidation, and the main reason people regret it.
- Pitted tin lining. On traditional tin-lined pans the lining is the cooking surface, and pitting means retinning.
- Corroded rivets. Where copper meets steel, detergent accelerates galvanic corrosion.
- Loose handles. Follows from the rivets, and it is not a simple fix.
Hand wash and a two minute polish once a month keeps copper looking the way you paid for it.
If you want copper that handles a dishwasher, buy copper-coloured stainless. It is not the same to cook with, and it is far easier to live with.
Frequently asked questions
Can you put copper pans in the dishwasher?
No. Alkaline detergent oxidises copper to a dull brown within a single cycle, and on lined pans it can damage the lining and corrode the rivets.
How do you restore tarnished copper?
A paste of equal parts salt, flour and white vinegar, rubbed on, left for a minute, rinsed and buffed dry. Half a lemon dipped in salt works for lighter tarnish.
Is copper-bottomed stainless dishwasher safe?
The stainless body is, but the copper base will dull and discolour. Many manufacturers advise hand washing for that reason.
Does tarnish make copper unsafe to cook with?
Tarnish on the outside is cosmetic. Damage to the inner lining on a tin-lined pan matters, because that lining is what keeps copper out of your food.
How often should you polish copper?
Once a month keeps it bright with very little effort. Many cooks let the outside develop a patina and only keep the cooking surface clean.