Make a paste out of baking soda and water and clean lightly with a toothbrush. Afterwards rinse. it works great and I picked it up from a numismatics forum.
3d whiting (crest)
penny bath
it really depends on what kind of juice
lemon juice, because it has antioxidense!>*^#$
well add juice to the penny
orange jucie
because you know what kind and you can try it on the pennys
woman
All bamboo cleans the air to a greater oor lesser degree.
A window viper would be the your answer !
Vinegar with salt.
septic