First thing to know is that ancient coins are different then the coins you are used too. The metal has combined with various elements in the ground and has minerialized. It’s delicate and cleaning requires a lot of patience and care. Without a whole suite of tools and experience at your back there is only a few safe things that can be done. Soaking the coin in distilled water is really the only way you can soften encrustations without damaging the coin itself. Then using something softer than the delicate coin to gently rub the dirt off one layer at a time. Toothpicks or bamboo skewers are great for this. Spend no more than 10mins at a time working on the coin before returning it to the distilled water and coming back another day. Change the water out every few days to once a week or so. This method will take months… Once you invest in a binocular microscope that is when the hobby kicks itself into high gear and you can use better tools.

Wow someone found the community! :-D Welcome. I got started in the hobby when I watched a video on Reddit of a time lapse of someone cleaning an ancient roman coin. I didn’t save it and have yet to find it again despite looking a few times. I was fascinated by it and started reading up on the subject. I didn’t want to start because I was afraid of destroying a piece of history. Then I found the 1/2 lb bag of practice coins that promised guilt free entry into the hobby. 95% of the coins were Roman because they’re apparently very prolific. I did find a coin that was paid to the crusaders. It lacks so much detail i haven’t been able to identify it outside figuring out its from the crusades. There were a few other non-roman coins but not in good enough shape that I was able to figure out what they are, outside of seeing they don’t look like roman coins.

Welcome :-) I’ve joined your community and look forward to posting there for some attribution help in the future. I was a lurker sometimes poster on the Reddit ancient coins subreddit, but I never really felt welcome because coin cleaning is generally negatively received there (with occasional exceptions). I can understand why because there is no shortage of people that buy ancients that are already cleaned and want to clean them, leading to an over cleaned coin at best and a destroyed one at worst. If you get those guys there send em here and we can reassure them that the coin is already clean. Maybe they’ll see examples of actually dirty coins that need cleaning and see that theirs is in good shape.