Tried to clean a Roman coin with cola, got a science fair volcano

Found a crusty old coin in a field near Hadrian's Wall last fall, figured it was Roman. Watched a video where a guy said a soak in cheap cola could clean it. Left the coin in a bowl of store brand cola overnight. Woke up to a fizzy brown mess all over my kitchen counter. The coin looked worse, covered in a sticky black gunk. My partner walked in and asked if I was doing a grade school volcano project. Learned that cola's acid can eat metal if you leave it too long, not just the dirt. Anyone know a safe way to clean a coin that's mostly just dirt and not much detail left?

3 comments

3 Comments

tyler6142mo ago

That cola trick is for modern coins, not ancient ones. Try soaking it in distilled water instead, it's way safer for old metal.

kevin_bailey2mo ago

Guess Tyler614's coins have never met the magic of a Coke bath.

ross.river22d ago

My old man collected coins for 30 years and he always said the same thing. That distilled water soak for like 24 hours is the gentlest way to go for anything older than 1800s. He had this one 1798 large cent that was caked in gunk and it came out looking way better after just sitting in distilled water. The coke thing works great for tarnished silver or modern clad but that acid is too harsh for old copper or bronze. If you really want to be safe, you can even switch out the water a couple times and use a soft toothbrush real gentle like. It takes patience but beats ruining something that's been around for centuries lol.