Newbie Needing Advice - Cleaning Coins?

Like most things in life, it all depends. Suggest posting just a few large and sharp photos for us to ponder. A Wheat cent with old glue on the surfaces might do well with an acetone soak. A badly rusted steel cent is usually toast. Looking forward to viewing some pics.

What kind of coins? As a general rule never clean coins, especially if you do not know what you are doing. Sonic cleaners are a no-no for coins.
John1

Maybe if you dropped your common coins in used motor oil then a sonic cleaner may work. I used a sonic cleaner at my former workplace to clean dirty machine parts. But I trust John1's opinion and avoid it entirely.

Do not clean your coins! We've all been at a place in our collecting life when we were experimenting with cleaning coins, and ultimately destroyed them. Avoid that stage in your collecting life and don't clean your coins.

For the record, the OP is asking about uncleaned ancient coins that are still "raw", and have just been dug out of the ground. Essentially, these are "metal detecting finds on steroids", and usually come out of the ground looking like little green rocks. They will need cleaning to make them look like coins again; every single ancient coin currently in existence, except for the gold coins, has had to be cleaned this way.

There is an art to cleaning ancient coins, not entirely unlike the art needed to extract a fossil from the surrounding rock. I know that I personally do not have the skill and/or patience for cleaning an uncleaned ancient coin, so I have never tried. The problem is, after a couple thousand years of being buried, the "dirt" that surrounds the coin isn't just dirt any more; some of the metal from the coin has dissolved and leached out into the surrounding dirt, and some of the chemicals in the dirt have reacted with the metal - making the boundary between "coin" and "not-coin" difficult to discern. But I do know a few rules of thumb.

- Acetone, by itself, will literally do nothing to an uncleaned coin.. unless for some reason someone took an uncleaned coin and put it into a PVC coin album. Acetone is only useful to an ancients cleaner if you use an oil-based cleaning method, and need to get the oil off the coin once you're done.
- Soap water, likewise, does very little to help. If regular water doesn't shift it, adding soap won;t make any difference.

There is a sequence of reagents that are used for ancient coins - you generally try to work your way down the list. The chemicals and processes get harsher and harsher as you go down, so you don't want to jump all the way to the bottom, when something milder would work better.
- Deionized water. Let it soak for several weeks.
- Olive oil. Also needs soaking for weeks. The traditional method of treating an uncleaned coin, and still used by some; inconsistency in modern olive oil production causes variable results. Using modern refined machine oils don't seem to have the same effect, as they lack the mild acidity needed.
- Picks and tools. "Diamond-dusted dental tools" are sold by ancient coin dealers for this purpose, to remove the stubborn bits of rock and debris from a coin's surface. Of course, you have to be very careful to remove just the debris, and not carve or create new detail onto the surface - that's called "tooling", and is universally regarded as a bad thing. Picks are what you want to use on a "desert patina" coin, because many collectors tend to like the cameo effect that results from the selective removal of encrusted sand from the high points on a coin.
- Electrolysis. Can give mixed results, and almost always strips away all of the original patina of a coin.
- Lye (sodium hydroxide). Yes, it's nasty and corrosive. But for some coins, it's the reagent of final resort. You will almost certainly get a pitted, corroded mess at the end of the process, but it might at least be an identifiable mess.

Be aware that you are probably not the first person to look at those "uncleaned coins" - they've probably been picked over by dozens of expert eyes before winding up in your bulk lot. Those expert eyes are likely to filter out most (but not all) of the true "gems", leaving behind the common coins and the coins they think might not clean very easily. As such, they will liekly come from multiple different sources, meaning each coin will require a different kind of treatment for optimal cleaning.

Finally, be aware that in the end, some ancient uncleaned coins are just "slugs" - they have no details left to reveal, no matter how carefully and expertly you try. Perhaps they were very heavily worn coins before they got buried, or perhaps they were buried in nasty corrosive soil or some other environment that completely destroyed their integrity. We've sometimes had "keen but clueless" people come onto the forum who insisted that if they kept trying harsher and harsher cleaning methods on their slugs, new details would eventually emerge. Sorry, but that's not how the Law of Entropy works. Once your coin is "cleaned" down to bare metal, further cleaning isn't going to reveal anything new.