Workshop humidity is a problem in that it can result in rust. Especially an issue on the surfaces of precision tools.
The humidity in the air comes from a number of sources: atmospheric, gas fire, blow torch, breathing and of course from some processes. Such as steaming wood, this will generate a lot of water vapour.
This means we have water vapour in the air in most workshops. There are a number of ways to control or limit the impact of this on tools.
Rust Prevention
You can spray tools with ACF-50. This works really well to stop rust. Not sure how often you need to treat surfaces, especially surfaces like lathe beds where they rub. Treating tools with ACF-50 is a great idea if you plan on leaving the workshop unattended for a period of time.
De-Humidify
You can remove the moisture from the air in your workshop. This can be done using an electrically powered unit or using chemicals.
Chemical dehumidifiers are available in most household stores. They range from a simple bag of calcium chloride chips that you spread into a container to a scented compressed disc.
These products absorb the moisture from the air and collect it in a reservoir. The downside is you have to keep on renewing chemicals.
Electrical dehumidifiers are readily available in a number of sizes. Most of the small units once again collect the water in a container that will need emptying regularly. Larger units can be plumbed in.
You can buy 12V dehumidifiers and so it is possible to perhaps run these off-grid.
Dry Heating
Don’t add to the problem, use a dry heater such as an electric oil filled radiator or central heating. Avoid open gas fired radiators or space heaters. In a small workshop a small “greenhouse” frost protection heater (~150W) with a thermostat is a good way of reducing the condensation.
Controlled Heating
You can use a heater that is temperature controlled and so comes on when the temperature drops below say 7°C.
Alan @ Woody’s Workshop has designed a control system based on dewpoint measurement: Dewpoint alarm monitor to help avoid rust issues in the workshop.
This uses the Magnus-Tetens formula and covers the temperature range -45°C to 60°C with an uncertainty of 0.35°C.
You can use this to switch on a heater, dehumidifier or both. Using a monitor like this will reduce running costs.
There are a few ideas here for coping with workshop humidity and you may find you need to use a combination of heat, de-humidifying and rust control with something like ACF-50.