Preparing Surfaces for Paint

 

Preparing the surface is a crucial part of the house-painting process. Generally, the more preparation work you do, the smoother and more long-lasting the finished surface will be. But anyone who paints his or her house learns quickly that there is a point of diminishing return when it comes to preparation. You must decide for yourself how much sanding and scraping is enough for you to obtain a finish that meets your demands. But whether you are attempting to create a glass-smooth finish with a professional look or you simply want to freshen up the look of your house, always remove and spot-sand all paint that has lost its bond with the surface.

 

Everything You Need:

Tools: pressure washer, paint scrapers, finishing sander, wire brush, stiff-bristled brush, file, sanding blocks, hammer, putty knife.

Materials: sandpaper, epoxy wood filler, caulk, colored push pins, tape.

Preparation defines the final appearance. For the smoothest finish, sand all the way to bare wood with a power sander (top of photo). For a less time-consuming (but rougher) finish, scrape off loose paint, then spot-sand the rough edges (middle of photo). Pressure-washing alone removes some flaky paint, but it will not create a satisfactory finish (bottom of photo).

 

Tips for Pressure-washing

 

Direct the water stream at a downward angle when pressure-washing siding. Avoid getting too close to the surface with the sprayer head, because the force of the stream can damage siding and trim. When pressure-washing high on the wall, use an extension attachment. Attach a rotating scrub brush attachment to clean hard-to-reach areas, like cornices and soffits. Check with the rental store for available pressure-washer accessories.

 

Tips for Protecting Your House & Yard

 

Protect delicate plants and shrubs with tarps when you are working near them. Also lay tarps on the ground around your house to collect debris. Turn off air conditioners and other appliances, and cover them with plastic sheets to protect them from debris and paint.

 

Remove shutters and decorative trim to protect them from damage and to give you better access to the surface of your house. Inspect the shutters and trim to see if they are in good repair, and fix them if necessary. Prepare, prime, and paint them before reinstalling.

 

Options for Removing Paint

 

Use a heat gun to loosen thick layers of paint. Aim the gun at the surface, and move it constantly. Follow with a scraper once the paint releases. Read the manufacturer’s directions and precautions.

Use chemical stripper to remove paint from delicate trim. Work in a well-ventilated area, wearing heavy-duty rubber gloves. Read the stripper manufacturer’s directions and precautions.

Rent a siding sander to remove large areas of paint on wood lap siding. Rent a sander with a disk the same diameter as the width of the reveal area on your siding. Get instructions from the rental store.


How to Prepare Surfaces for Paint

  1. Pressure-wash your house. Pressure-washing cleans the surface and dislodges loose paint. Allow the house to dry thoroughly before continuing with the preparation work.
  2. Scrape off loose paint that was not removed during pressure-washing, using a paint scraper. Be careful not to damage the surface with overly aggressive scraping.
  3. Remove loose paint in hard-to-reach areas with detail scrapers (available at building centers and woodworker’s stores). Some have interchangeable heads that match common trim profiles.
  4. Use a finishing sander with 80-grit sandpaper to smooth out rough paint.
  5. Use sanding blocks and 80 to 120-grit sandpaper to remove paint and smooth out ridges in hard-to-reach areas of trim. Sanding blocks are available at building centers in a variety of shapes and sizes, like the teardrop design shown here. Or, you can make your own blocks from dowels, wood scraps, garden hose, or other household materials.
  6. Inspect all surfaces for cracks, rot, or other damage. Mark damaged areas with colored push pins or tape so you can locate them easily when making repairs.
  7. Repair all the damaged areas.
  8. Use a finishing sander with 120-grit sandpaper to sand down ridges and hard edges left from the scraping process, creating a smooth surface. Also sand repaired areas.
  9. Scuff-sand glossy surfaces on doors, window casings, and any surfaces painted with enamel paint, using a coarse abrasive pad or 150-grit sandpaper. Scuffing creates a better bonding surface for primer and paint.
  10. Fill cracks in siding and gaps around window and door trim with paintable siliconized acrylic caulk. The caulk makes a tight, long-lasting seal.

Tips for Removing Clear Finishes

 

Pressure-wash stained or unpainted surfaces that have been treated with a wood preservative or protectant before recoating with fresh sealant. Clear topcoats and sealants can flake and peel, just like paint. Use a stiff-bristled brush to dislodge any flakes of loosened surface coating not removed by pressure-washing. Do not use a wire brush on wood surfaces.

 

Tips for removing paint from metal & Masonry

 

Use a wire brush to remove loose paint and rust from metal hardware, like railings and ornate trim. Cover the surface with metal primer immediately after brushing to prevent new rust from forming. Scuff-sand metal siding and trim with medium-coarse steel wool or a coarse abrasive pad. Wash the surface before priming and painting.

 

Use a drill with a wire-wheel attachment to remove loose mortar, mineral deposits, or paint from mortar lines in masonry surfaces. Clean broad, flat surfaces with a wire brush. Correct any minor damage with masonry repair products. Remove rust from metal hardware with diluted muriatic acid solution.

Caution: When working with muriatic acid, wear safety equipment, work in a well-ventilated area, and follow the manufacturer’s directions and precautions.