How To Unstick Stuck Coins? (Dime, Two Pennies)

I'd try an acetone soak.

I'd start with an overnight soak in distilled water. That should work if they are stuck together from sugar residue from soft drinks, some glues, etc. If that doesn't work, acetone would be a good next step.

As there is no such thing as a "universal solvent" which can dissolve everything equally well, this is a case where following the "polarity latter" would be helpful:
- Try water first.
- Then try ethanol, methanol. isopropanol, or some similar alcohol.
- Then try acetone.
- Then try xylene. Eucalyptus oil would be a similarly-acting, more environmentally friendly substitute, but will leave your coins smelling all eucalyptussy.
- Then try hexane. Gasoline would work here too.

Working your way down this list should eventually hit on something that works to dissolve the glue. Of course, it's easy for me to suggest this, given that I work in a lab with bottles of all these things just sitting around and fume cupboards where I can slosh them about without worrying about breathing in the fumes. All of those solvents except for water are volatile, toxic and flammable so you may not want to fill your house with them.

And they're all, apart from water, more expensive than the 12 cents you'd get by freeing those specific coins, which is why we'd recommend starting at the water end of the ladder, because the water is cheapest.

If just "separation of the coins" rather than "removing whatever the goo is" is your priority, then I can also suggest an ultrasonic bath like the ones used for jewellery cleaning. We wouldn't normally recommend ultrasonic baths to clean collectable coins because they cause "rub", but we're not talking about "keepers" here.

Finally, we can't discount the possibility that the coins have actually corroded, melted, or otherwise fused together physically, such that no solvent can now separate them.

Be careful - Don't end up saying:

"I spent $72 on solvents to unstick 12¢ of coins"...........

It would appear that Sap has the best list of things to try..

SUCCESS!!!

I partook of what's sometimes referred to as "the universal solvent"--water--and soaked my mini stack overnight. When I reached for it this morning, what to my wondering eyes did appear but three separate coins! For the record, we've got a 2004-D dime, and two 2019 pennies. Thanks to everyone for your suggestions.

So... anyone know what I can buy for 12 cents?

Well done.