Here are the finds from 3 nights at some Chicago parks this week. NOX is king of the parks and beaches IMO. I also brought my xp Deus x35 coil and my ratio of good targets to trash dug was considerably better with the NOX.
I use water and toothbrush first to see what it looks like. Then for deeper cleaning in soak in peroxide overnight. Then rinse and toothbrush again. If still dirty put in peroxide bath for a few more hours. Rinse and toothbrush and let completely dry. Coat with vaseline or petroleum jelly and let sit overnight. Then rub clean with a soft cotton cloth. Works well with copper or brass. Only use water and soap on silver, unless heavily corroded or encrusted. Then I use baking soda scrub with my fingers lightly enough to ID it. Nickel is tough. The peroxide method works, but much abbreviated. Most of the time I just brush nickels with a dry toothbrush and then coat in petroleum jelly.
MineLab E-Trac, MineLab Safari, MineLab Explorer XS,
White's 5000 D, White's 6DB, White's 5000 D GEB
Sunray X-1 for the ML's, Garrett PP for the White's and a Backhoe
I never use hot peroxide only room temp. I start with water and soap and toothbrush. Clean as much dirt and crust off as possible to see if more cleaning is needed. Then use peroxide. Come coins are too far gone to get any ID and some coins have unidentifiable crud on them. Not much you can do other than physically remove with fingernail or some kind of a tool. Test the techniques on an old crusty copper penny before trying on the one you want to preserve. Don’t even try zinc pennies, they will it work well.