Dehumidifier and humidity percentage.

CapnMac, The info on Dew Point was a good review, forced me to review some college thermo and also think about the alternative situation you discussed. Dew Point and relative humidity are related, so conflation is not necessarily a bad thing 100% RH at 70 Deg F implies the dew point is 70 Deg

I have always looked at my "environment" that needs protected as the room or space I am in, not a gun safe, cigar box or tool box, hence my general interest in controlling Relative Humidity. (mostly because I got sick of my shop tools getting rusty) If a gun safe, cigar box or tool chest is the environment that needs to be controlled, options relating to Dew Point or Relative humidity are available, and as CapnMac indicates, heating the inside of the safe to a temp above the Dew Point prevents rust from forming.

Automatic De-humidifiers for rooms are quite common and with my multi-purpose goal, I think the room dehumidifier option is best for me. Also dehumidifiers function by removing moisture from the air.

For a safe, the golden rods are listed as dehumidifiers, but as CapnMac indicates they are heaters, and drive the interior temp above the dew point, which lowers the relative humidity, but do not remove moisture. The idea of combining a Golden Rod with a desiccant seems like a good idea.

I live in a relatively dry climate (Idaho) and run a HUMIDIFIER in the winter because it gets TOO DRY in the house. I try to keep the house around 40-45% relative humidity. That said, year round I have a Holden Rod heater and desecant in my gun safe. The safe is about 30-35% humidity and 70-72* F. Constant temp with low humidity. I have no wood-stocked firearms in the safe to be concerned with.