Posted 10/30/2010 10:25 am
The key is not to over-scrape so that you get into the metal and remove the patina or damage the actual coin. As Tim states, be patient and keep in mind that it may take years before you get the "concrete" off. If you are sure that you're dealing with a "bump" of crust, you can carefully use a dental pick on it - sometimes a big flake will come off so that the olive oil can work itself deeper into the crust and continue to loosen it. Try alternating between olive oil and distilled water, too. Good luck!
