Moisture: the safe deposit box's worst enemy.

[bcbgcbrcb]

Having worked in banks for 25+ years, I can tell you that vaults do not have any air control system inside so the summers during overnight hours can get pretty hot inside and the winters are the opposite, depending on the climate where you live.

[frankbmd]

Bill,

Protecting your collection from a thermonuclear weapon or an electromagnetic pulse might require additional measures.

[conor912]

Originally Posted by bcbgcbrcb

Having worked in banks for 25+ years, I can tell you that vaults do not have any air control system inside so the summers during overnight hours can get pretty hot inside and the winters are the opposite, depending on the climate where you live.

Sounds like attic/basement/garage conditions to me.

[e107collector]

I've used one of these for many years. Just plug it in to reactivate every month or so. I love it!

http://www.cabelas.com/product/Liber...t=dehumidifier

Tony

[TanksAndSpartans]

I use this to monitor the situation: http://www.lowes.com/pd_396632-53921...ductId=3830957

I found this recommendation:

http://www.archives.gov/preservation...ly-papers.html

But Googling turns up several variants - I'd be concerned about a RH below 30 or above 60.

Given I keep the cards in an air conditioned house, I don't find the humidity gets that far over 50 even in the humid months, but I still use this to knock it down some:

http://www.amazon.com/Eva-dry-Renewa.../dp/B000H0XFCS

I'd do some testing and if I found the bank was letting the RH get too high because the AC was turned off at night or whatever reason, I'd think about taking my cards out at least during humid time periods. Lack of humidity in the air can cause the cards to get brittle, but for my climate, I don't think that's as much of a concern.