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Thread: How to stop rust

  1. #31
    Join Date
    Aug 2015
    N. Texas
    Quote Originally Posted by Jim Becker View Post
    Keeping the shop air above the dew point really can help with this. A lot of rust problems on machinery is due to condensation because of temperature.
    ^^This would certainly keep it from raining in the shop!

    I'm with Alex. I have always believed the machinery must be kept above the dew point of the air, or the dew point of the air below the temperature of the machinery. So, either the tool 'warm' (relatively), or the air 'dry'. Either one will prevent the moisture in the air from condensing on a rust-prone surface.
    Molann an obair an saor.

    If Heaven ain't alot like Texas, I don't wanna go. - Hank Jr.

  2. #32
    Join Date
    Sep 2007
    Longview WA
    Blog Entries
    Quote Originally Posted by Doug Dawson View Post
    Sounds like you need a dehumidifier in your shop.
    One problem with a dehumidifier is in an unheated shop it can freeze up in cold weather.

    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  3. #33
    Quote Originally Posted by Jim Koepke View Post
    One problem with a dehumidifier is in an unheated shop it can freeze up in cold weather.
    It's about as unlikely to freeze in Port Arthur, Texas as it is to rain frogs. (Maybe I spoke too soon? :^) But more generally, yeah.

  4. #34
    Join Date
    Jul 2016
    Lebanon, TN
    Let the experiment begin.

    One roll of 24" x 10' of magnetic vinyl, $42 delivered to me with tax (

    I have 4 power tool tops and beds covered, got a couple more to do.

    Stuff was easy to cut and goes on in a couple of seconds. I also like the fact that it gives a bit of upper surface protection as well, I tend to put things down on top of some of these tables when that tool is not in use.

  5. #35
    I went 9 months with no protection when I first got my table saw/bandsaw. then I had a crazy warm day in January followed by a wet night and somehow the garage filled with moisture. overnight my hand tools and cast iron tops rusted.

    I cleaned them all up and glidecoated everything and oiled my hand tools. I ordered a dehumidifier that night and though it does run quite a bit Nothing has rusted since. I oil/coat every few months or as needed. I also added these to each drawer.

  6. #36
    Join Date
    Apr 2018
    Cambridge Vermont
    When the dead of winter can reach -40 and you are a part time hobbyist keeping your shop heated isn't always practical. It's the extreme temperature changes that cause problems around here. I wish I could get away with a dehumidifier. I'm trying to find someone local who has a mini split heat pump. I know they don't work down that low but if something like this could be a good addition for those nights when the heat pump isn't going to cut it.

  7. #37
    Join Date
    Nov 2003
    Central North Carolina
    When air is very cold, like -40, there is almost no moisture in the air. When warm air is cooled, any significant moisture that is in the air must be given up as the air is cooled. This is the "Dew Point" or temperature at which the moisture begins to condense out of the air. When it does, it will form on any surface that is colder than this dew point temperature. The warmer the air, the more moisture that it can hold, but as this warm air cools, much of this moisture must condense out of the air because the cooled air can no longer hold it. The temperature/humidity ratio at which the air humidity begins to fall out of the air is the dew point.

    Very cold machinery will develop condensation on it and rust will form when brought into a warm shop because of this, but if the shop stays cold (below dew point) condensation does not happen. Keeping the warm air relatively dry with a dehumidifier or air conditioner will keep the dew point low, so moisture won't condense out of the air if the temperature drops some. If it drops a lot, and suddenly there is a good chance that the dew point will be reached and the moisture in the air will begin to condense. In the Summer, when we get a cold front, it will rain, because the cooled air will cause the moisture in the air above it's dew point to condense. The same thing happens in your shop as warm air is cooled, but it's slower and not near as violent because the air temperature is dropping more slowly, but it will indeed rain on your tools, just in very small droplets. Covering the tops, just like throwing tarps over outdoor items will protect the tops from the rain, but not the internals.

    keeping the humidity of your shop air low will keep your tools from rusting, even if the shop temperature varies, as long as it stays above the dew point. Keeping the humidity of the air in your shop relatively low will also help you preserve your wood and projects that you make won't shrink and split when you take your finished projects into your warm, relatively dry homes.

    My shop is less than 20' above and about 100' from a 300 acre lake. When the temperature outside falls rapidly to below freezing, my cars and trucks develop a thick frost on them. My shop is well insulated, so the temperature doesn't change that rapidly, so I don't have severe rust problems on my shop machinery and I never cover them. I do have heat and air conditioning in the shop, but only run it when I am there or if the temperature outside will go significantly below freezing for an extended period of time, and mostly to protect my water lines, latex paint, batteries, etc. from freezing. I do wax my cast iron, but almost never see any evidence of rust on anything inside my shop. The wax is applied more to make project wood slide over the surfaces easily than to protect the metal from rusting.

    Last edited by Charles Lent; 04-01-2020 at 4:46 PM.

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