Toning in a jar....

tracker

Years ago when my parents were still alive, they saved a lot of their loose change... putting it in jars, coffee cans, etc... . I notice a lot of the coins which were stored in large jars have spectacular toning, yet the coins in coffee cans and containers which block out light have virtually no toning whatsoever. Just seems odd that light would play a part in toning. Any thoughts?

nwcs

From what I understand, heat (from light) accelerates toning by speeding the chemical change (oxidation) of the coin surface.

windwhispersintrees

Or, it could be that the jars(old fashioned wire bale & glass lid type?), might not have been as airtight as the cans (plastic lids?)
I like the sunlight/heat theory, assuming the coins weren't stored in a dark closet.

perfectstrike

Light, heat and the amount of contaminants present are all factors. Mixing copper and silver in the same container will accelerate toning under all combinations I've tried. Covered vs uncovered doesn't seem to have that much significance. Heat with sunlight produces much quicker reaction than heat without sunlight. I haven't tried and metal containers, but clear class and opaque glazed ceramic. I live in the Metro Atlanta area and a single SAE in a shaded exterior location already looks AT on one side.

perfectstrike