So I know there is a wide range of opinions on the issue of cleaning coins, and whether it is something that should be done, and under what circumstances it should be done. This is one of these examples where the coin isn't something special, won't be going out for any grading, and holds more sentimental value than anything else, and won't be sold. With all that being said - let's take a look at this 1857 Flying Eagle Cent before the cleaning: As you can see the back was loaded with gunk from it's prestigious 167 years of living. When I got this coin, the gunk on the reverse often bothered me enough that I did extensive reading on the topic of cleaning coins, yet I never did anything with it until today. Behold the after cleaning: It looks much better after a 20 minute pure acetone soak, and an hour bath in distilled water. Air drying of course! Let me hear your thoughts on the before and after!
Your process is completely acceptable. Acetone and distilled water do not harm the coins surfaces. No harm no foul, IMO.
The way you cleaned that coin will not hurt it so you did good. However, you got rid of that black “gunk” as you called it and you also stated that it “holds more sentimental value” so I can’t help but think some of that sentimental value is forever gone.
The sentimental value is more based on the possession of the coin rather than appearance. It's been a coin that managed to stay in our family for four generations. Being the proud owner of the coin now and being able to keep it going for years to come is where the sentiment comes from.
Much approved after cleaning. Glad to hear that the coin has been in your family for so long. It's well worth taking care of. Bruce