I would encourage you to place a temperature/hygrometer in your shop for a few weeks. I suspect you will find very high humidity and relatively low temperatures. As a consequence, whenever the sun comes out and your shop begins to warm a bit, all your castiron and steel tools are the coolest surface in the shop. Guess where the condensation is going to form? (you got it, your tools!).
There are two basic aproaches to tackling the problem. The majority of the responses have focused on products that place protective coatings on your tools to help prevent condensed moisture from oxidizing the underlying metal. These can be very effective at stopping rust and, at least up front, they are relatively inexpensive. But if you have lots of steel and castiron the elbow grease and time spent maintaining these protective coatings eventually begins to eat into your shop time. More to the point, its just no fun. We go out to our shop to create -- and occassionally destroy -- not polish our tools every week!
Which brings me to the second option. Namely, dealing with the excess moisture. Get rid of that moisture and ensure that the humidity is always low enough to keep the dew point well below the ambient temperature of you shop (which means no condensation). Initially, begin by trying your best to seal the shop up as well as possible. Weather strip the garage door and access doors, caulk around windows if they leak, if you have an attic access door, weather strip it as well. If your concrete floors are hopelessly porous, you can have them sealed (I would save this step to last unless you are fortunate enough to have an empty garage -- your floors have to be in pretty bad shape to be too porous for the final solution). Once you have made a reasonable effort to control the ingress of additional moisture it is time to look into a good dehumidifier (something in the 50-70 pint/day range). Set the dehumidifier to maintain a shop humidity of 45-50%RH and you should notice a tremoundous reduction in surface rust.
I maintain my shop at 40-45%RH (I have health issues and overheat easily, so the slightly lower humidity setting allows sweat to evaporate more quickly). In the 2-1/2 years that I have been dehumidifying my shop I have literally gone from applying protective coatings and polishing my tools from as often as once a month to less than once a year. Even then my polishings now are mostly to remove the rust *I* cause from transferred sweat!
Aside from the initial purchase of the dehumidifier I have found that during the most humid summer months the dehumidifier uses about $0.45 to $0.50 in electricity each day (or less than $15/mo based on a ~30day average during summer). Of course, in the winter months it uses next to no electricity as it seldom ever needs to run. If you decide to purchase a dehumidifier I strongly recommend models with digital humidity settings. They may misregister by as much as 5-10%RH, but once you know your models error it is very easy to set it to maintain a stable humidity (much more so than the older analog dial models). If you don't have a convenient floor drain (or other low-lying drain alternative) I would also suggest purchasing an external dehumidifier pump to automatically drain your dehmidifier. The dehumidifier dumps into the pumps reservoir tank and when the level is high enough the pump automatically comes on and pumps the water up and out (can be to a sink, washing machine drain, or -- in my case -- up and out the same window my window-mount A/C-heater is installed in).
Which approach you take is entirely up to you. I, however, am very greatful that I invested in a dehumidifier -- I just could not stand working in a 70F shop (when I had the A/C running) with 80% humidity. (I only run the A/C when I am in the shop, so it never gets a chance to make much of a dent in the humidity on its own.)
Good luck!
There are two basic aproaches to tackling the problem. The majority of the responses have focused on products that place protective coatings on your tools to help prevent condensed moisture from oxidizing the underlying metal. These can be very effective at stopping rust and, at least up front, they are relatively inexpensive. But if you have lots of steel and castiron the elbow grease and time spent maintaining these protective coatings eventually begins to eat into your shop time. More to the point, its just no fun. We go out to our shop to create -- and occassionally destroy -- not polish our tools every week!
Which brings me to the second option. Namely, dealing with the excess moisture. Get rid of that moisture and ensure that the humidity is always low enough to keep the dew point well below the ambient temperature of you shop (which means no condensation). Initially, begin by trying your best to seal the shop up as well as possible. Weather strip the garage door and access doors, caulk around windows if they leak, if you have an attic access door, weather strip it as well. If your concrete floors are hopelessly porous, you can have them sealed (I would save this step to last unless you are fortunate enough to have an empty garage -- your floors have to be in pretty bad shape to be too porous for the final solution). Once you have made a reasonable effort to control the ingress of additional moisture it is time to look into a good dehumidifier (something in the 50-70 pint/day range). Set the dehumidifier to maintain a shop humidity of 45-50%RH and you should notice a tremoundous reduction in surface rust.
I maintain my shop at 40-45%RH (I have health issues and overheat easily, so the slightly lower humidity setting allows sweat to evaporate more quickly). In the 2-1/2 years that I have been dehumidifying my shop I have literally gone from applying protective coatings and polishing my tools from as often as once a month to less than once a year. Even then my polishings now are mostly to remove the rust *I* cause from transferred sweat!
Aside from the initial purchase of the dehumidifier I have found that during the most humid summer months the dehumidifier uses about $0.45 to $0.50 in electricity each day (or less than $15/mo based on a ~30day average during summer). Of course, in the winter months it uses next to no electricity as it seldom ever needs to run. If you decide to purchase a dehumidifier I strongly recommend models with digital humidity settings. They may misregister by as much as 5-10%RH, but once you know your models error it is very easy to set it to maintain a stable humidity (much more so than the older analog dial models). If you don't have a convenient floor drain (or other low-lying drain alternative) I would also suggest purchasing an external dehumidifier pump to automatically drain your dehmidifier. The dehumidifier dumps into the pumps reservoir tank and when the level is high enough the pump automatically comes on and pumps the water up and out (can be to a sink, washing machine drain, or -- in my case -- up and out the same window my window-mount A/C-heater is installed in).
Which approach you take is entirely up to you. I, however, am very greatful that I invested in a dehumidifier -- I just could not stand working in a 70F shop (when I had the A/C running) with 80% humidity. (I only run the A/C when I am in the shop, so it never gets a chance to make much of a dent in the humidity on its own.)
Good luck!
