Preparing and Priming Metal

All metals oxidize if they’re not properly coated, and paint can’t adhere to the oxide coating. To stop the oxidation process, strip away grease, dirt, and rust, then apply a primer that is chemically formulated to neutralize oxidation. This primer also provides a surface to which the finish coat can adhere. Primer made for automobile bodies is usually a good choice, but consult with your paint dealer to make sure. You also can buy special metal paints that combine the primer with a finish coating. Use these over surfaces that are in at least fairly good condition. Aluminized paint includes aluminum dust as a pigment and also works as a combination primer-finish on metals not exposed to severe weathering.

The finish paint must protect against weather and abrasion. Once the surface has been adequately primed, you can use almost any paint—exterior-grade for outdoors, indoor types for inside jobs. However, don’t apply a lacquer over anything but a lacquer-based finish paint or primer. Even polished decorative metals, such as brass, copper, and bronze, need protection if you want them to keep their shine. Buff tarnished hardware items with fine steel wool, metal polish, or a felt wheel and abrasive compound, then coat them with clear lacquer or polyurethane.

Tools: Paintbrushes, wire brush, drill with wire-brush attachment, sandpaper, and steel wool.

Wash and wire-brush surface. Wash the surface with a commercial degreaser, then wirebrush away any rust or peeling paint. A brush wheel Remove paint. Paint remover works better on metal than on wood. Use it to take off multiple layers.

attachment on a power drill makes short work of this task.

Rusty-Metal Primer - Standard metal primer works only when all the rust has first been removed and the surface is completely dry. Rusty-metal primer, on the other hand, can be applied directly on top of rust. It will not smooth the bumpy surface of the rust, but it will stop the rust from spreading and will provide “tooth” for the finish paint to adhere to.

Feather edges of well-stuck paint. Use a loose piece of sandpaper or a hand sanding block to feather the edges of the remaining sound paint. Otherwise, the repaired area will show through. Finally, wash or brush any paint flakes and dust away from the work area.

Prepare gutters and downspouts. Clean and paint the inside of metal gutters first. Gutters and downspouts (shown) often need only spot-sanding and priming.

Apply primer or sander. Treat sound paint with liquid sander. This product produces a “tooth” to which the new paint can adhere. Alternatively, sand the old paint thoroughly or apply alcohol-based primer.

Sand the primer. Lightly sand primed surfaces with very fine sandpaper or steel wool. Don’t sand through the primer.

Painting Metal

Spray, brush, or roll paint onto metal finishes. Whichever application you choose, bear in mind that several thin coats will hold up better than one or two thick layers. Let each coat dry before applying the next. Brushed or rolled-on paint should dry at least overnight (36 hours is better) before you apply another coat. A good job calls for patience and good lighting so you can correct problems before the paint dries. Work the paint in one direction and move from dry to wet areas. Don’t lap brushstrokes by painting over a dry edge. Smooth corners, too, so they don’t dry with accumulations of paint.

Tools: Brushes and drop cloths.

Apply the paint. Flow the paint on with smooth, even strokes. After a few minutes, check the freshly painted areas for drips, runs, and sags. When you’re painting a complicated piece such as a radiator or chair, be sure to look from several different angles so you can spot places you missed.

Seal gutters. To make galvanized gutters really last, paint the inside surfaces with an asphalt-based paint. Besides protecting the metal, it seals tiny leaks. After using the appropriate metal primer, the top coat of paint can be almost any outdoor type. (Aluminum or plastic gutters never need to be painted.)

Painting Masonry

Several types of paint will adhere to masonry. A paint dealer will carry paints designed for many types of surfaces and situations. Because they dry to a very hard finish, epoxy paints are probably the best all-around choice for floors, walls that are washed frequently, and exterior applications. Portland cement paint is another good choice; it works well on all walls except those previously painted with another type of finish. Latex paint, probably the easiest to apply, also adheres to foundation walls. Check with your paint dealer for other types suitable for specific applications.

Before painting a masonry surface—especially basement walls and floors—be sure to correct any existing moisture problems. If you don’t, no paint will adhere. Also, remove peeling paint with a wire brush, and make necessary masonry repairs. To finish the prep work, degrease the surface using detergent and water. Then etch the surface with a mixture of 1 part muriatic acid to 3 parts water. This removes and neutralizes alkaline material in the mortar joints. (Be sure to wear rubber gloves and a long-sleeved shirt to protect your skin from the acid.) Finally, rinse the surface with clear water. After the surface has dried thoroughly, apply the finish with a wide short-bristled brush or a roller cover with a long nap.

Tools: Scrub brush, paintbrush, roller with an extension handle.

Painting a floor. Apply a degreasing solution to an oily garage or basement floor. Some products spray on; others require a scrub brush. Use a roller with an extension handle to paint a floor—to prevent backache from bending over. Paint one section at a time.

Fill in a pitted surface. Smooth a rough-textured wall (but not a floor) with a 1:1 Portland cement and tile-grout mix, scrubbing it into depressions. To smooth a light texture, use an abrasive tool.

Apply the paint. Apply paint with an old or cheap stiff-bristle brush. You’ll have to push hard on the brush and even scrub it into very porous surfaces. If you want a rough texture, use a long-nap roller to apply the finish.

Painting stairs. To paint steps that are used daily, paint the risers and every other tread. When the finish is dry on those, paint the treads you skipped.

Log in to comment