Cherry darkens rapidly when exposed to sunlight.

Another alternative is to wash it with a sodium hydroxide
(caustic soda lye) solution. The darkness of the effect is
dependent on the strength of the solution. You can rinse
with white vinegar to neutralize the caustic, or just leave
it exposed to the air for a few days as residual sodium
hydroxide will react with carbon dioxide in the air to form
sodium carbonate.


Isn't Draino mostly sodium hydroxide? Can't remember, and don't have any
on hand.