Currently toning

 

You may want to keep a close eye on the coins. Bank vaults are notorious for being kept at a high humidity because they are designed to protect paper & documents - not coins. And humidity causes coins to tone and often even corrode. Once it begins, it can happen quite quickly and it may well progress way beyond what you would like. And if left unattended it can also cause damage and the coins will lose most of their value.

This came up some time ago on another coin forum about banks. So me being a curious person and having numerous banks here in the Chicago land area, I went to many of them and asked about the additon of humidity in safe deposit areas. Having accounts in several I thought they would at least not throw me out if the question was weird. EVERY single bank I went to said that is just not true. Most said to add humidity to one area and then air condition the rest would not be economically feasible. Most banks I checked had the safe deposit box rooms open during working hours so adding humidity to such an area would just not be possible. All banks I checked also stated additional humidity would do more damage to documents than just being dry. Then there is the personal problem. Individuals that can not stand high humidity could not work in such an area and therefore specialized personal would have to be hired.

 

 

I rather suspect the explanations are because the people working in the banks really don't know much about them. Ever hear of a humidifier ? They are not expensive and they are very easy to install in the HVAC system.

 

As one who has actually built the banks from the ground up, I can safely say they have them.