Painting Exterior Metal

  1. Steel is a ferrous metal, which means that it is subject to rusting if exposed to moisture and oxygen.
  2. If painting previously uncoated steel, completely remove all rust with a wire brush.
  3. Next, apply a rust-inhibitive specialty primer to prevent rust from occurring. Note that two coats of primer will serve to extend the durability of the top coat paint.
  4. Finally, apply a coat of top-quality, 100% acrylic latex paint or oil-based paint over the previously primed substrate.

  5. Spray painting is also an option for steel. If using an anti-rust spray paint like Valspar® Anti-Rust Armor Enamel Spray Paint, it is best to paint before installing to protect the rest of the exterior from spray mist. Place the steel item on a work bench to have access to all sides for even coverage. Use short dusting strokes rather than one heavy coat. Follow topcoating instructions on back of the can.

    Note: There are some paints on the market today that are known as "Direct to Metal" (DTM) paints. They can be applied to metal surfaces without applying a primer.

Aluminum and Aluminum Siding
Aluminum is generally a very good surface to paint; however, there are a few potential problems of which to be aware:

  1. Check previously painted aluminum —especially aluminum with factory applied paints, such as aluminum siding, mobile homes or outbuildings. Does the paint look badly "chalked?" If the act of rubbing your fingertips across the aluminum surface yields a white powder, then the old coating is badly weathered and must be completely removed with a cleanser —like trisodium phosphate (TSP) or substitute. Once the surface has been cleaned of dirt, chalk, mildew or other contaminants, it can be painted with a premium-quality, 100% acrylic latex house paint.
  2. Note about Paint Finish Selection:
    Since aluminum is prone to denting, we recommend you use a flat or satin finish paint. Glossier paint will tend to accent any dents that may be on the surface.

Spray Painting
No matter which metal you're painting, spray painting might be an option.
If the object is able to be moved so overspray doesn't damage nearby items, consider spraying for convenience and the ability to apply a thinner coating.

To properly spray metal:

  1. Ensure the surface is clean and dry. Remove any dirt, grease, etc.
  2. Cover nearby area to protect from spray mist.
  3. Prime bare metal with an anti-rust primer to enhance corrosion resistance. This will also give the paint a better surface to adhere to. Use short, dusting strokes to cover substrate. Allow an hour* to dry before topcoating.
  4. Top coat with a multipurpose enamel or anti-rust enamel. Move can back and forth, releasing button after each stroke. Overlap each stroke. It is better to apply several thin coats than one heavy coat, which may cause runs or drips. Shake can frequently during use to ensure paint stays mixed.

  5. *Drying times may vary. Check directions on back of can.

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