Found these coins yesterday I think the two larger ones are too corroded to identify, the other little I found about 8 inches from these two

[kmk]

 

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[Bucket Lister]

The way I look at it with bad coppers is that I cannot ID them in their bad condition so they are totally worthless. If I try a strong cleaning method, the worst that can happen is that they remain worthless. For me, over half the time, I get an ID and a date range. Then I have some useful data for my historical interest.

+1. I can't speak for any of the methods suggested/tried, because I haven't tried them except for ultrasonics, and that was many years decades ago.

 

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[Caliche]

Do the cheap $20 ultrasonic cleaners from Amazon do anything to coin crust / mineral deposits?

 

[Almy]

I'd guess that the lower one is a King George II British halfpenny. They were minted 1729 to 1754. I think I can see a large, left-facing bust with the back of the head quite near the rim of the coin. These were counterfeited a lot.

 

[Gare]

Any update yet ? NICE finds also

 

[Bucket Lister]

Do the cheap $20 ultrasonic cleaners from Amazon do anything to coin crust / mineral deposits?

IMO/E, you get what you pay for.

Those cheapies appear to be intended for eyeglasses, which usually aren't the most challenging when it comes to cleaning.

IDK if they make units specifically for coins; some articles are about using ultrasonic jewelry cleaners for coins.

Again, it's been many decades.