Any thoughts on cleaning excavated hard metals?

Being a hard metal digger, much of my scrap metal poundage comes out of the ground. From years down below, it indubitably has a heavy patina -- a polite way of saying it's oxidized to hell and back.

When in the ground for an extended stay, copper, brass and bronze all oxidize to a nearly identical smooth brown hue, often chocolate brown. The metals can also show splotches of typical red rust stains, compliments of any nearby ferrous metals.

Has anyone ever tried to bulk bath/wash/soak heavily-tarnished copper, brass or bronze? I'm thinking in terms of maybe 100-pound plastic bins loaded with assorted hard metals.

I realize nothing -- short of industrial tumbling -- will actually get long-buried metals up and shining again, but I'm thinking a soak might make it a lot more presentable to a buyer while also showing a metal's true colors to aid in sorting metals.

Related question: Is it even worth the trouble, profit-wise, to clean such copper/brass/bronze?

I would think for scrap value a wire brush would be the best way to get the big crud off. Beyond that I see no reason to clean scrap.

Now if it might be something that could be sold as a useful object then a bath of vinegar and salt works well. Might try a low wattage reverse electro plating to remove the outer layer. I have some experience with metal detecting and finding stuff you can't identify right away. So if you are not sure what something is then perhaps its better to hold onto it for now. Mike

+1 on white vinegar. soaking for a couple days does wonders on steel at least.

If the peices are small enough get one of the electric drum type cement mixers from harbor freight. Throw your metal in with a dry bag of quickcrete or some small gravel and let it tumble it will clean it nicely

If you try the cement mixer just throw some sand in it. It'll work better than anything else you use.

Looks like I'll try that improvised tumbler route. Concrete mixer here comes some dirty copper.

I do understand that, in the long haul, it isn't always worth a clean-up effort when it comes to final scrap price. However, some of my dug items are so discolored I actually have to sell the dealer on the fact it's truly hard metal.

And, yes, I always keep in mind that some/many objects are worth much more than their scrap value -- sometimes hugely so. It is not hard to find what are sometimes called architectural salvagers, who pay way beyond weight value for vintage hard metal items. Not long ago, I found two solid brass gargoyles on brass bed posts tossed in an old town dump. In scrap they were a tidy 50 bucks. Instead, I sold them to an antique shop for three times that. What's more, I now have a buyer who wants to see "everything" I have before I scrap it. Yet another phase of scrapping.

Thanks for the help folks.