How to Prepare Steel for Paint

Even though steel will accept any kind of paint, unless the surface is prepared and keyed properly the paint will soon peel off. This is especially true with a galvanized steel surface. Correctly prepared and painted, the finish could last for over a century; witness a vintage car manufactured in the late 19th century and still bearing the original paint. Imagine how the same car would look of it was first painted with a modern high-tech polymer.

Portable hand-held siphon sandblaster (optional)
Sandblasting grit (optional)
Rented compressor (optional)
80-grit emery paper
Coarse steel wool
Wire brush
120-grit emery paper
Organic rust remover for large areas
2-inch paintbrush or 7-inch medium nap paint roller for large areas
Coarse-bristle broom for large areas
Garden hose with a high-pressure nozzle for large areas
Cleaning rag
Denatured alcohol
Micro fiber tack cloth
Zinc chromate self-etching metal primer (aerosol)

Instructions

- 1
  Remove all traces of rust before painting steel. One of the easiest ways of doing this is by blasting the surface with an inexpensive portable hand-held siphon sandblaster powered by a compressor; this method is especially useful on irregular surfaces such as cast iron patio furniture.
- 2
  Work outdoors and load the sandblasting hopper with commercially available sandblasting grit, start the compressor and aim the nozzle 4 to 6 inches from the rusty metal. Press the trigger and work the sandblaster back and forth as you would a paint spray gun.
- 3
  Abrade the rusted steel surface with either some 80-grit emery paper, coarse steel wool or a wire brush to remove every trace of rust. For an extra smooth finish complete the job with 120-grit emery paper.
- 4
  Use an organic rust remover on large surfaces such as roofs, garage doors or corrugated iron. Apply the material liberally with a 2-inch paintbrush or 7-inch medium nap paint roller. Allow 15 minutes for the liquid to react.
- 5
  Scrub down with a coarse-bristle broom. Rinse off with a garden hose fitted with a high-pressure nozzle. This material will not harm vegetation or injure your skin.
- 6
  Clean the hand-prepared steel area to be painted with a rag soaked in denatured alcohol. Wipe down with a micro fiber tack cloth to remove any remaining sanding residue. This is not necessary if organic rust remover has been used.
- 7
  Prime the steel surface with an aerosol can of zinc chromate self-etching metal primer. Shake the can and hold the nozzle 12 to 14 inches from the surface; spray with even, overlapping sweeps. Apply a single coat and allow an hour's drying time before handling.

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Painting