Very nice Indian Head Cent coins, I agree with Mackdog, your coin has allot more detail there. Maybe try to use a toothpic, a toothpic will clean off crud allot better than a toothbrush. Sometimes that dirt is like concrete and won't come off without force. Sometimes corrosion looks like coin. If not removed it will continue to eat your coin. NGC use acetone, then xylene baths to preserve coins. Everyone has there own cleaning methods and opinions, I'm not saying anyone is wrong. Just how I like to do mine. Allot of people say they love that green patina on there copper/brass coin, but I know that green is eating my coin.