Got a bunch of uncleaned ancient coins today and starting to clean them...

dthigpen

By soaking them in olive oil for a couple days, then I'll wash in soap + water swish/rinse and light soft bristle toothbrush until I start seeing the metal of the coin itself; then back into the olive oil for a week and repeat until they're clean. Any recommendations on speeding this up or optimizing this process/making it safer?

PuddlePirate

I have several techniques I use depending on how badly encrusted they are. For me, I have found that after the first week or two of olive oil soaking I start using light household type acids. Try a white vinegar soak in between your olive oil soaks. If heavily encrusted, household cleaning ammonia (the bronze coins will turn the ammonia dark blue), alternated with lime/lemon juice and distilled water soaks.

I also have several brushes of various types and stiffness. If you use the small brass brushes (used for cleaning battery terminals - they cost about 1$ at an automobile supply store like NAPA) use a very light hand otherwise any fine details will simply go away They are good however for working through the heavy crud until details start to show and you go to a lighter brush.

If you discover a patina on the coin don't use ammonia on them unless you want to risk lifting the patina and having a "splotchy" textured coin. I have tried electrocuting them upon occassion, nothing stronger than a 9v battery. Sometimes you get surpising results with electrolysis. To do that you need to make your own "battery acid" which is quite simple; about 7 drops of lime juice to 1oz of water. Put the positive wire to the coin with a paper clip or aligator clip (whatever) but keep it dry, ground goes to fluid. The lemon juice will bubble and change colors - (blue for bronze and green for silver) let it go for about 15 maybe twenty minutes. Brush lightly afterwards. If you leave a thin flan coin in too long you can seriously damage it so pay attention! A 9v will last about 2 hrs so it gets expensive. Have alot of Patience, take your time and remember that no matter how good you are some of those coins are never going to come up beyond poor. The ones that do however make everything worthwhile.
Good Luck!

CIVITAS

I've heard of decent results with WD-40 because it's a much lighter weight oil, it can penetrate the crud quicker than olive oil.

MSD61

A dremel with a polishing wheel....LOL!!! WD-40is also a good choice

Askari

Hey Michael, I love your sig line pic -- is it the logo for a coffee shop?