If you REALLY want to stress your brain,and your eyeballs....search a couple freezer zip locks full of 4000 or so Mercs.
Once a proof, always a proof. When a proof grades below 60, it enters the realm of "impaired proofs."
Thank you for that. And maybe you can tell me if there is a good source of information as to the details on specific coins that cause them to be ... errors, I guess. Kind of like the "spot the difference" game.
“This above all: to thine own self be true, And it must follow, as the night the day, Thou canst not then be false to any man.” ― William Shakespeare, Hamlet
Nah, impaired proof is when the boss marks the bottle and the maid/butler adds water to it so he won't know they have been takin a wee nip.