How do I make my darkroom dry?
Easiest way to maintain a dry darkroom is to use a dehumidifier. If you live in a very humid area, like the southern part of the U.S., you may need to leave the dehumidifier on ALL THE TIME. You will need to connect a drainage hose to the dehumidifier so it does not fill up and stop working.
Also, you should have a device, whether it’s a dehumidifier, fans, or a small heat source to keep the room at 70°F-80°F. When a dehumidifier is running, it will typically give off enough heat to warm up the space by itself.