Tho some frown on it, put some baking soda on two fingers with IH in between and gently rub the penny with a little warm water for 30 - 60 seconds. Rinse in distilled water if you have it. Be sure to get all the loose stuff off first. It's worked for me for IH's and Silver coins. I have an 1891 IH in my gallery that I thought was roached, but one time with this method, and I couldn't believe it. Good Luck!