"Correct" humidity level for gun safes?

[Monkeyleg]

My safe has a Goldenrod dehumidifier in it, and I've put a small hydrometer in there to monitor the humidity. For months it's ranged between 24 and 28%. Today there's been a few thunderstorms and the humidity outside (and inside) is probably 90+ %. In my safe it's 36%.

Is that acceptable for a period of a day or a few days? Does anyone else measure their safe's humidity?

 

[Double Naught Spy]

The lower the humidity in the safe, the better. That said, Goldenrods do nothing to change the humidity level in the safe. Instead, they create a thermal uplift draft and slight warming of the air. Warmer air is able to hold a higher amount of moisture whereas cooler air holds less and will drop moisture (sort of like what happens with dew). So, the warmer air and draft essentially helps keep the moisture in the air and in motion so as to preclude moisture from settling on your firearms.

Some folks think the Goldenrod actually removes moisture from the air. Given that the safe is closed most of the time and probably has a fairly good seal against the elements, just where is the moisture going to go? A goldenrod does not work as a dehumidifier. Dehumidifiers do remove moisture from the air and either deposit the moisture in a reservoir in the device or send it down a drain.

 

[Airwolf]

My Sentry 14 gun safe is running around 70-75 degrees/50-55% humididy with a goldenrod in it. The safe stays closed 99 percent of the time (opened just a couple of times a day for a few moments each time).

The safe is not fireproof and is by no means anywhere near airtight.

I have had zero problems with rust or wood being too dry.

On the other hand I've got a Sentry document safe that is fireproof and it gets VERY humid. I've never measured it but without dehumidifer crystals papers get damp feeling and very musty.

 

[Monkeyleg]

Thanks for the reply, Double Naught and Airwolf.

Goldenrod's website says the their dehumidifiers work by warming the air that comes in through air leaks at the bottom and allowing the warmed air to escape at the top of the safe. In fact, they make a point about having air passages/escapes for both top and bottom.

Doing a little checking on metals and humidity, I found that at 15% humidity no steel would develop rust, nor would brass or copper tarnish. Of course, the article didn't mention whether wood might crack due to drying out.

At some point, there's going to be a learned THR metals scholar who will give us all the right answer. Until then, I'm trying to get the humidity in my safe back into the 20's.