What would you consider the optimum % of humidity in a gun safe to discourage rust? I have a humidity meter in my safe that I try to keep around 25%. Just a random number that seems good to me. I live in mid-coast Calif. and use just an appliance light bulb in the safe to develop enough heat to maintain low humidity.
I know there are commercial humidity "sticks" designed for this.

I have a Golden Rod Dehumidifier in my safes. Works for me.

However, your "small" bulb will probably work also. How small?

Constant temperature change is not good. Condensation will rust your guns and the safe itself.

Use a golden rod if you must. I never used one. I keep the temperature constant and use gun socks. Been working well for me for years.

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