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Fix-It-Yourself Project #104
"How to Correct Common Paint Problems"

Tool and Material Checklist

Paint, Paint cleaner, Sandpaper, Sandpaper holder, Paint remover, Power sander/brush, Concrete patch, Drop cloth, Trowel, Caulk, Putty, Paint roller, Brush/roller cleaner, Turpentine or thinner, Exhaust fan, Solvent, undercoat, Sponge, Steel wool, Paint scraper, Wire brush, Paint brush, Crack filler, Patching plaster, Wood putty, Caulking gun, Putty knife, Roller tray, Paint pail, Glass scraper, Punch, Louvers, Vents or wedges


1. Stained Spots from Rusting Nail Heads

The problem is created by the use of uncoated steel nails and excessive moisture under the paint. The uncoated steel nails obviously cannot be removed, but the moisture problem can be corrected. Make an effort to locate the source of the excessive moisture. Check for leakage from the eaves, evaporation from plumbing pipes located nearby or sweating caused by heat from a bathroom or kitchen. If the source of the moisture can be located, attempt to eliminate the problem by shutting off the condensation that causes the moisture.

Remove the stained paint around all nail heads by sanding the area or using a wire brush. Sand right down to the nail head, then sand the nail head itself to make it bright by removing the built-up rust. Use a nail punch to countersink all nail heads approximately 1/8" below the wood surface.

Apply one even layer of undercoat over the countersunk nail and the area around it. After the area is primed, fill the countersunk hole with a good grade of caulking compound. Allow to dry and then apply one coat of a good grade of outside house paint. After adequate drying time, apply a second coat. This should cure the problem.

2. Peeling of Paint Under the Overhang of a Roof

Paint sometimes peels in spots under the overhang of a roof or in other areas of a house that are protected from weather. Such peeling is normally caused by a build up of "salt" deposits which would normally be washed away by rain in exposed areas.

To correct this problem, remove the old, peeling paint by sanding the surface thoroughly. After sanding, prepare a solution of three heaping tablespoons of any good powdered detergent to one gallon of water. Wash the sanded surface with this solution. Rinse with clear water and allow to dry.

After the surface is thoroughly dry, apply two coats of a good grade of undercoating paint. After the undercoat has thoroughly dried, apply one good coat of a top quality house paint. Under some conditions, two finish coats may also be required. This treatment normally corrects the peeling condition.

3. Flaking of Paint

Paint flaking is caused by moisture collecting behind the painted surface. Moisture enters the wood siding from the unpainted side. The absorbing and drying of the moisture causes repeated swelling and shrinking, thus breaking the paint film and causing it to pull away from the wood surface.

The first step in solving the flaking problem is to try to locate the source of the moisture. Check the area for leakage from the gutters or eaves of the house. If the area is near a bathroom or kitchen, pipes may be sweating or leaking or excess heat may be building up condensation.

It may be necessary to install attic louvers, moisture vents or exhaust fans to correct the build-up moisture. Scrape and sand away all flaking paint. Remove all paint as far out as approximately 12" in all directions beyond the area where the flaking condition occurs.

Sand the surface down to the unpainted wood and spot prime the area with a good grade of undercoat. Protect against a repeat of the moisture problem by caulking all seams, holes and cracks that may appear in the freshly sanded area.

After the caulking compound has thoroughly dried, apply at least one food coat of a top quality house paint according to the manufacturer's directions. Two coats are sometimes needed. These steps should totally remove the problem.

4. Spot Peeling

Spot peeling sometimes occurs on the siding of a house in areas exposed to the sun's heat. This usually is caused by moisture trapped in the siding and drawn to the surface by the sun's rays. This moisture pushes the paint away from the surface.

The first step in solving the problem is to try to locate the source of the trapped moisture. Check carefully for leaks in the gutter or eave of the house. If the peeling area is near a kitchen or bathroom, it may be necessary to remove the moisture and sweating build up by installing an exhaust fan.

Louvers placed in the overhang of the roof or wedges and vents placed in the siding sometimes allow the trapped moisture to escape. Remove all the old paint in the peeled area. Scrape off the paint approximately 12" beyond any sign of the peeled condition.

Sand the surface down to the original wood and prime it with a good grade of wood undercoat. Avoid a repeat of the peeling problem by caulking all holes, cracks and seams with a good grade of caulking compound. After the caulking compound has had time to thoroughly dry, apply at least one coat of a good grade of house paint. In almost all cases, this totally corrects the problem.

5. Peeling Downspouts and Gutters

Gutters and downspouts normally peel because they were not properly treated and primed when originally painted. Galvanized metal usually has a thin, invisible film that causes many paint problems.

Remove the loose paint from the downspouts and gutters with a wire brush, scraper or some other stiff tool. If the job is a big one, it will be a lot easier if the downspouts and gutters are power brushed or sanded. Be sure to remove all loose paint in the peeling areas. Unless this is done the problem will occur again after another painting. Do not try to take shortcuts. Now is the time to correct the problem by doing the job right.

If you are painting with latex paint, clean the sanded area with a good grade of solvent. Apply a heavy coat of the solvent and allow it to evaporate. Special solvents are available for treating galvanized metal. After the solvent has evaporated, apply the latex paint directly to the bare galvanized area. If large areas are treated it will be well to finish the job with two top coats.

If you are painting with an oil base paint, prime the sanded areas with a good grade of metal primer. After the primer has dried, apply one coat of a good grade of metal paint. Finish off the job with at least one coat of a good quality house paint. In extreme cases, it will be wise to use two coats for the finish application.

6. Cracking or Alligatoring

Extreme cracking, sometimes known as alligatoring is caused by applying a second or third coat of paint before the previous coat dries. In some cases, cracking or alligatoring is also caused by using an undercoat that was not made for use with the type of finish coat applied to the surface.

The only solution to the problem is to completely sand away the cracked or alligatored paint from the surface, brush the area thoroughly to remove dust and loose paint particles. Apply once coat of a good quality undercoat paint. Allow the undercoat paint to dry thoroughly and then apply a second coat of a top quality house paint of the desired color. This will completely correct the problem.

7. Checking of a Painted Surface

Checking usually occurs on a painted plywood surface. As the plywood veneer ages, it cracks from repeated expansion and contraction. This weathering and aging causes the painted surface to check. When checking occurs, the entire checked area must be sanded smooth. It will be easier if you use a power sander.

After the sanding is complete, prime the bare wood with one coat of good grade undercoat. Fill all holes, cracks and seams with a good grade of caulking compound. After the caulking compound and undercoat paint have thoroughly dried, apply one layer of a good grade of outside house paint.

In some extreme cases, the plywood may be so aged that it is wise to replace the wood completely. If new plywood is added, you can prevent a recurrence of checking by sanding the surface of a new plywood smooth. After sanding, apply one coat of a good grade of latex wood primer. After the primer has thoroughly dried, apply one or two coats of a tops quality outside house paint.

8. Mildew on Paint

Mildew is caused by a combination of high humidity and high temperature. This creates a growth of fungus on the paint film. Mildew must be removed from the surface. If it is painted over, it will grow right through the new coat of paint.

Make a solution of 1/3 cup of any type of powdered detergent and 1/2 cup of household bleach mixed in one gallon of warm water. Scrub the entire mildewed surface thoroughly with this solution. Scrub the area hard and then rinse lightly with clean water.

Apply one coat of a good grade of undercoat paint and let it dry. After the undercoat layer has thoroughly dried, apply a finish coat of mildew resistant outside paint or a top grade of latex outside house paint. When these instructions are followed, the mildew problem is removed.

9. Blistering

Blistering is caused by moisture trapped in the wood and drawn to the surface by the sun's rays. As the moisture rises to the surface, it pulls the paint away and causes blistering. Try to locate the source of the excess moisture and eliminate it. Check first for leakage from the gutters or eaves of the house.

If the area is near a bathroom or kitchen, it may be necessary to install an exhaust fan to remove the excess heat, steam and moisture. Moisture vents or wedges can also be installed in the siding to permit the moisture to escape.

Scrape or sand away all the old paint in the blistered area. Scrape it right down to the wood. Scrape the unblistered paint out approximately 12" away from the blistered area. Sand the scraped are thoroughly, right down to the fresh wood. Then prime it with a good grade of undercoat paint.

Try to block future moisture problems by sealing all cracks, holes and seams with a good grade of caulking compound. After the caulking compound and undercoat have dried thoroughly, apply a second coat of a good grade or outside house paint. This eliminates the problem.

10. Chalking and Flaking on Masonry Surfaces

Chalking and flaking on masonry surfaces are usually caused by inadequate preparation of the surface when the paint was applied. This causes the paint to flake off or powder. To correct this problem, remove the chalking or flaking by brushing with a wire brush or sandblasting. If the job is big, use power sanders or wire brushes.

After the wire brushing or sandblasting is completed, seal all cracks with a good grade of concrete patch or caulk. After sealing the cracks, apply a good grade of masonry conditioner, using it exactly according to the manufacturer's instructions. After the masonry conditioner has thoroughly dried, apply one or two coats of a good grade of latex house paint or an exterior masonry paint. Your flaking problem is corrected.