Try a 40 gram hydrosorbent silica gel. It stays active for a month or longer. You have to recharge it in a oven for a couple of hours. So you may want to buy two and have a extra to put in the safe while you take out the old one and charge it. If you have a larger safe you could use a Remington dehumidifier. About twice as large and thicker than the 40 gram and it can be recharged by a outlet.
Comments
Perfect for safes.
[ Not my sale...just an example].
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