Cleaning Coins With An Ultrasonic Cleaner

Oh, and I wouldn't rub it dry, I would pat it gently dry with a fresh microfiber cloth then allow about 30 minutes to air dry the rest of the way. Perhaps in a container with a desiccant.

Thanks for that. Do you think if it were suspended in the water held in a plastic basket therefore not rubbing against anything would that be ok? I am only trying to do this so I can see what the coin is (very black at moment)

Ultrasonic cleaners need some kind of detergent or surfactant in the liquid to work properly - just putting water in there will make little discernible difference to soaking the coin in water in an ordinary container.

Using ultrasonics to clean coins has two major drawbacks: uncertainty over the exact nature of the detergent (with the possibility the detergent could harm or discolour the coins) and the impossibility of suspending a coin in the solution without having the coin touch anything - not other coins, not the sides of the cleaner, not a plastic tray or string or anything else that could be used. One of those super-powerful electromagnets that can levitate things might in theory do the trick, though I don't think the ultrasonic cleaner mechanism would still work with such a powerful electromagnetic field nearby.

The problem is that anything placed in an ultrasonic cleaner vibrates back and forth very rapidly. If it is touching anything, the vibration creates a friction spot, causing wear at that spot.

Ultrasonics have their place - I imagine they'd be very good at helping clean up coins dug up out of the ground. But for ordinary coins that have simply discoloured, I wouldn't recommend them.

If you want to see what your very dark-coloured coin actually is, try scanning it or taking a picture, then brightening the image with photoshop or some similar program.

I did try it as coin was pitted, only an 1856 5 centime but after all the advise wont do anything with any others.
Great site anyway I will certainly be digging out the other coins/medals that I cant identify.
Thanks everyone.

I have an ultrasonic cleaner I bought for cleaning carburettor parts. I have experimented with grimy, circulated coins and it does shift the dirt. I have tried different detergents and found many are brightly coloured and can leave stains on the coins so, one step forward and one step back! The stains usually come off with acetone. I use water from my rain water tank which is very soft (minimal dissolved salts compared with our local town supply).
I have looked at surfactants available on the market -common at rural supply store for adding to herbicide sprays. But, so many different chemicals and claims, I steered clear. And, many are sold in 20 litre drums when I would only want a few drops.

I was concerned with coins rubbing container, or each other, so made up separators from thin polycarbonate sheet with multiple holes drilled to allow free flow of water. Haven't noticed any signs of buffing or rub marks but I have not tried uncirculated coins which don't need any such treatment anyway. I have quite a few common coins in UNC -maybe I should try a few?

My conclusion is that this does clean grimy coins but, not really more effective than an overnight soak and toothpick treatment.
I have also tried with a water/acetone solution (acetone is relatively expensive and evaporates quickly) and that does get rid of some greasy type deposits. But, a swap with acetone on a cotton bud does that too (toothpick for stubborn deposits).

I have read that some dealers clean ultrasonically. Anyone know anything about their practices?

My suggestion is feel free to experimant if you have access to an ultrasonic cleaner but don't expect any miracles. And, be it on your own head if you try it with valuable coins and downgrade them!
Of course, if you come up with outstanding results post details here.
I would not suggest purchasing a cleaner just to try for coins.

Jeff
PS. Ultrasonic cleaners do work well with jewellery, especially with ornate patterning. But, check carefully before disposing of the water -I had to recover a diamond from the S bend of the sink. It shook out of a workmate's engagement ring. She was not happy but the jeweller who reset it did confirm my theory that the mount was already loose and it could have fallen out any time (lucky for me).

And also try some battery acid, a wire wheel on a bench grinder and some Butane torches too work.
Yes kids will be kids. However, once more, remember that as I pointed out, some waters are worse than others. In fact the biggest problem people have with house plants is using tap water for them. Tap water contains so much STUFF that just shouldn't be used for plants of coins.
Vinegar too is man made product. And all man made products can and do differ from one batch to another and one manufacturer to another.
Any time someone suggests using a man made product on coins, always remember the same STUFF they say may not be the same one you can buy. You have to be real carefull of experts on the internet. And too, remember that if what someone says doesn't work, TO BAD. It's your coin, not theirs, so who looses?