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Painting a cast iron radiator

Filed Under: fix-it, home decor, remodeling

Though many people in our neighborhood have updated their heating systems, we've never considered it. Cast iron radiators, which we have in every room of our house, are surprisingly efficient. If you have unpainted radiators in your home, most home heating experts recommend keeping them that way. Unfortunately, all of ours were painted when we moved in.

If you're going to do anything with a painted radiator, it's important to first make sure that you know what kind of paint you're dealing with. Since your radiator is likely in an older home, it could be covered in lead paint. If so, it's best to research proper ways to protect yourself from that hazard.

If your radiator is lead-free, you basically have two choices. You can either sandblast the beast, something we've not yet tried. Or you can just grab a piece of sandpaper and get started. Sandblasting is by far the best quality option, but if you've ever tried removing a cast iron radiator, you'll know why we chose the sandpaper. Those things are heavy and removing them requires draining your entire system.
Once you've decided on your method, use a wire brush to scrub away all dust, grime, and loose chips. Sand well, and you're ready to paint.

You have a few choices when it comes to paint. You can choose to spray on a high-heat paint if you like, but in hot water systems such as ours, the radiators don't get hot enough to require it. Instead, we use an oil-based primer followed by the oil-based color of our choice. Latex is not recommended because it can lead to rusting.

Though there's plenty of debate on the topic, there doesn't seem to be a consensus on color. Some people believe that color affects the efficiency of the radiator, while others say the effect is negligible. What most experts DO agree on is that metallic paint is not a good choice, as it reduces the radiator's ability to heat a room. If you like the look of the old, unpainted radiator but yours is painted, you can recreate it by using a bronzing technique.

Finally, we've experimented with different types of brushes to hit all the tight spaces in a radiator, but have yet to come up with one we love. Has anyone out there painted a radiator and found a tool that can get into all the hard-to-reach places?


  • Scott

    On the other hand, if you do decide to remove them you can take them to a powdercoat house and never have to repaint them ever again. The powdercoat will outlive your heating system.

  • Bethany Sanders

    Very good point, Scott. If we decided to remove one, we'd probably have them all done. We removed one once in our bathroom and it was such a mess. If I'm going to go through that again, I'll do every last one!

    Thanks for reading!

  • Linda

    Hi, Bethany... Yes, there is indeed a specialty tool designed specifically for this task. It's called an "angled radiator brush" and and the one we have is made by Stanley. It has a long handle and the brush end is offset at a 45 degree angle in order to get behind radiators and other hard-to-reach places. We found ours at a specialty paint store.

    Best wishes, Linda

  • Jean Pellerin

    We took the big old cast iron radiator outside and after washing it down (it was in pretty good shape- not rusted) , I painted it with high-temperature aluminum paint I got at a Paint & Hardware supply. It is a really runny stuff- you don't "spread" it on- you kind of wash it on (more like pour)- and it drips like mad. To get into the inside parts (impossible with a regular brush) - I took the handle off a foam brush and duct-taped a piece of wire coathanger on. Then I could reach long parts and bend the wire to reach into odd places. It was still hard- but it worked.
    Now- could someone tell me how we can get it back into the house??? They took it out sideways,but it took three guys. Now only two are here.... and it's a narrow door with steps.
    I think they are going to kill themselves!!!!

  • 4 Comments / 1 Pages

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