Cleaning a DJ

Hi.

I have been given a dj that had some copper coins kept in it. It has marks from them!

I have given it a few soaks in hot oxy and tried to scrub it with a brush but it's had no effect.
Any other ideas.
The marks are at the bottom so it's a but hard to reach!

I sometimes use a few ml of CRS to clean the conicals I use for yeast starters. I carefully tilt the conical to get the acid over the entire surface. I don't know what sort of oxide/tarnish you have but any acid such as citric or vinegar might help.

Hot caustic soda is great for stubborn stains if PBW doesn’t shift it.

Acid based cleaner might react will copper so make sure you're well ventilated. Does bring it up an absolute treat though
Caustic is unlikely to work imo, its mainly for organic matter.

It might sound stupid lol but what about cola?

I used to put uncooked rice in with the oxy and give it a good shake. This used to shift stubborn stains.
Don't eat the rice afterwards!!

Cheers,
Jon.

So the citric acid seems to have cleaned this up a treat. Cheers for all the input guys!

a bit of stainless steel chain with small links is ideal to throw in with warm water and allows you to swirl it around.