Yea, for my coppers it would take forever. It's a slow process and yes, it will continue to take off the dirt and green, but I ain't that patient. I have had them in there for 6 mos and still didn't get all that green off of them. But you will not like what is under that green lol Sometimes the green hides the pits that are under there. It is worth a try on the different types of conditions your coins are in, (dirt, green, red colors, etc...) They will all clean differently.