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How do I Paint Cor-Ten Steel?

Daniel Wallace

Cor-Ten, or weathering steel, is a popular option for exposed steel elements. The rust forms a protective barrier and inhibits further rusting while giving the steel a rich and natural color. Despite this property, you may want to paint it for increased longevity or for a different color. In addition, Cor-Ten constantly exposed to water or salt spray can corrode faster than normal mild steel because the protective properties of the barrier are stripped away. Fortunately, it can be painted just like mild steel. Painted Cor-Ten has both the protection of the paint and its natural properties.

  1. Put on the dust mask and use the wire brush to remove all loose rust. Don't be shy, but it is okay if some of the rust won't come off.

  2. Make sure the material is clean and dry. Wipe it down with rags.

  3. Hold the primer can approximately 10 inches from the material. Depress the nozzle after you start moving the can and release it before you stop moving. Don't go back and forth in one "shoot" because the thinner and more even the coat of paint, the better. Paint in the same direction until you have the timing down. Keep feathering the paint on until the accessible portion is primed. If you need to move the piece to reach another part, wait at least 15 minutes. Let the primed piece dry. The can will say the time, but it is generally about 30 minutes to an hour. You can touch up spots as you see them but keep a light hand and keep the spray can moving.

  4. Paint the final coat the same way that you primed it. Always keep the can moving and stay at least 10 inches from the material to prevent runs. Allow the piece to dry completely before moving to avoid damaging the finish.