Place your pennies in each of the different liquids or mixtures. Wait 3 minutes. Scrub the pennies with a sponge. Observe. For better results, let the pennies sit in the liquid or mixture overnight.
Coca Cola with work the best. (1)
Soap and water will work the best. (3)
Lime juice will work the best. (2)
Ketchup will work the best. (3)
Vinegar and salt will work the best. (4)
Vinegar and salt worked the best. After only 11 seconds the pennies in vinegar and salt were noticeably cleaner. And after a little scrub they were shiny like new. We are going to leave them over the weekend to see if they get even shiner!