Vinegar and peroxide for cleaning coins of crust.

I can't help you with an exact answer to your question, but all i can say is that if you are not sure what coin is there and it's potentially a good one, you better wait for an answer of someone with experience.

I tried vinegar and water solution in some copper coins and they ended up in a funny pink color, fortunately they were not rare or big value coins.

Something that i tried with a few coins fully covered of crust was to remove it with pliers, you gotta be very careful and 'cut' the crust on the edge but regulate the strenght to not damage the coin, once i remove most the edge, then i put them in a small plastic thing with water in the fridge. Usually it's enough to do this a couple of times and then the crust falls out without problems. BUT, if the metal of the coin is too damaged, when you use the pliers it can break the coin as if it is clay.

Hope it helps & good luck.

I'm always strongly against using vinegar, because vinegar is made of acid, and acids are... well acids. They tend to damage other materials.

I am a coin collector as well and I will simply say that under no circumstances should you ever clean a coin. PERIOD! Now if you don't care about the value because its a junk coin. vinegar and peroxide works really well. I used it on a quarter and nickel I found recently. The vinegar does more as far as eating the metal so I would say more peroxide than vinegar. Now if you think the coin may have value, some hobby and coin shops have a cleaning product that is more or less safe. It's still advised that you just use soap and your index finger to clean it or just don't. Hope that helps.