Is An Acetone Bath Safe?

Acetone does not alter the surface of the metal, it merely dissolves any contaminants present on the surface of the metal. It's a strong solvent, so it is useful for removing oils, dirt, etc. without needing to physically touch the coin and risk scratching it. I would caution against using it on copper unless you plan to follow it up with a Verdi-Care or Blue Ribbon treatment to protect the surface.

However, like any solvent used on coins, there's a chance that the surface UNDERNEATH the dirt might be less attractive than the dirt. Test on coins you don't really have any attachment to, such as dirty junk silver.

Acetone will remove skin oils that would damage the surfaces in the future. It also contains traces of acid. I would not finalize with an acetone rinse for that reason. Your final rinse should be in water, distilled if possible, pat with a dry cloth and let air dry for a bit.

The problem is coins sometimes get things adhered to them. You remove that stuff and what is under the gunk is worse than if you had left it there. Old black stuff on copper coins is generally something I would not try to remove. You might find the surface below the gunk to be pitted and corroded, which is worse than what you started with.

Most circulated Morgan dollars do not require any type of cleaning. There are rare cases where a coin may have some glue or tape on it that can be aided by an acetone dip but those are rare.

Acetone will not remove toning. An acid dip can do that but circulated Morgans are almost never dipped since a lack of natural color will, very often, result in a "details" grade which reduces the value to melt.

So long story short - DO NOT ATTEMPT TO CLEAN YOUR COINS. If you find a rare date in bad shape, you can send it to a conservation service such as NCS. Before doing that post pictures because, more likely than not, your coin is naturally beautiful and already appealing to collectors. Most collectors love natural toning.