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How to Prepare Walls for Painting (page 3 of 3)

The key to a successful paint job is in the prep. Learn how to remove wallpaper, strip wood and patch walls to get them ready for a new coat of paint.

Excerpted from Do It Yourself Home Improvement

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Working With Wood

Woodwork provides the finer detailing in a home and its finish is a stamp of quality. To produce good results you must prepare surfaces, including doors, windows and decorative woodwork for moldings or paneling.

Stripping Wood
A good finish is often achievable by recoating the existing surface. However, you may need to strip woodwork before redecorating — the existing coating may be so bad that it cannot be successfully recoated; it may be painted, but you want a natural wood finish; or it could have a natural finish but you want to paint it or apply a different finish. Beware of surfaces with lead-based paint, which is toxic and now found only in older properties. It is a health risk if heated with a heat gun, and fine particles created by sanding are also toxic. Paint-testing kits are available to identify lead-based paintwork.

Using a Heat Gun

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Turn the heat gun on and direct the nozzle at the wood surface, leaving a gap of a few inches between the two (Image 1).

After a few moments, the paint will begin to soften and bubble, at which point use a shave hook or scraper to lift the old paint free (Image 2).

Move the gun along to the next area and repeat the process. Use a shave hook to remove paintwork in recesses, such as on paneling (Image 3).

Working Safely

  • Take great care using a heat gun. Wear goggles and a respiratory mask, and perhaps gloves. Take any other precautions that are advised by the tool's manufacturer.

  • Do not hold the gun for too long over the wood, to avoid the risk of scorching it or even setting it on fire.

Solution Stripping

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Wearing gloves, a mask and goggles, use an old paintbrush to apply the stripper (Image 1). Use dabbing strokes to build up a good layer of the stripper on the wood's surface. Allow it to soak in and react with the paint. This may take only a couple of minutes or up to half an hour.

Once the paint has bubbled up, scrape it off using a scraper and/or a shave hook (Image 2).

Thoroughly clean the surface afterward (Image 3). Mineral spirit and cold water are usually best, but check the stripper manufacturer's guidelines.

Paste Stripping

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Apply the stripper with a filling knife or small trowel to a depth of about 1/8 inch — or deeper if there are many coats of paint (Image 1). (Wear gloves, a mask and goggles.)

If your manufacturer specifies it, cover the entire surface with a special cloth. Leave for 24 hours. Use a scraper to peel away the paste (Image 2).

Thoroughly clean down the area (Image 3). If the manufacturer suggests it, use a "neutralizing solution" or use white vinegar and then clean water.

Dipping Doors
Removable items such as doors can be "dipped" professionally. The whole item is submerged in a tank of powerful chemicals, which lift all traces of paint from the wood surface. Many companies offer a pickup and delivery service.

Covering Old Paint

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Sometimes a natural wood finish may not be possible—if the wood is too rough, or the paint too ingrained to strip. Old beams may have stained finishes or may have been painted at some stage. You can have the paint sand-blasted away by a professional company but this is expensive, and extremely messy. An alternative is to apply the paint effect shown here.

Completely paint the beam, using an oil-based white eggshell (Image 1).

Apply a wood stain over the top of the eggshell. A mid-oak color is very effective (Image 2).

Rub varnish, oil or shellac across the whole surface to provide the effect of an oak beam (Image 3).

After half an hour, buff off the varnish, oil or shellac with a clean cloth. Some will remain embedded within the wood grain, resulting in the appearance of a natural wood beam (Image 4).

Preparing Beams

Natural wood beams are often tricky items to prepare for decoration, because of flaky surfaces and often very crumbly edges where the beam meets plaster. Trying to fill the edge is difficult and often ineffective, as the filler too crumbles and falls away. One way to secure the edge is to apply a clear matt varnish to the beam, overlapping slightly onto wall or ceiling surfaces. The varnish both binds the surface and provides a natural look. The wall or ceiling paint may then be cut in along the edge to create a neat finish.

Filling and Sanding Wood

Wooden surfaces are seldom completely smooth. Filling dents and sanding improves the finish. The type of filler to be used depends on whether the wood is to be painted or a natural finish applied. If it is to be painted, use powder filler — flexible filler can be used in joints or cracks. If a natural wood finish is to be applied, use a "stainable" filler the same color as the finish.

Priming and Filling Before Painting

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Prime bare wood before using filler to make it adhere better. Primer also makes it easier to see areas that require filling. If wood is painted, use primer only if there are large, bare patches — for instance, on external woodwork. Any knots in bare wood must first be coated with knotting solution (Image 1).

Allow primer to dry. Mix up filler, and apply to holes, dents or divots, using the flexibility of a filling knife blade to press in the filler (Image 2).

Allow filler to dry. Sand to a smooth finish (Image 3). Deep holes may require refilling and sanding to provide the best finish.

Filling for a Natural Wood Finish

Apply colored putty to holes in the wood surface with a putty knife. The putty color should match the natural wood finish to be applied.

Once the putty has dried, sand it smooth. Then apply coats of your chosen finish.

Further Information on Sanding
Sandpaper should be chosen according to the condition of the surface. So, for rough surfaces, begin by using a rough paper. As the surface becomes smoother, reduce the coarseness of the paper

Remember that sanding produces dust. This should always be brushed away before a coating is applied.
A vacuum cleaner nozzle is ideal for removing dust from baseboards or the profiles of moldings.
The best finishes are normally achieved when the wood has been wiped down with a damp cloth before coating, removing the finest residues. This is essential when sanding flat surfaces such as window sills.

Courtesy of DK - Do It Yourself Home Improvement © 2009 Dorling Kindersley Limited

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Excerpted from Do It Yourself Home Improvement

© Dorling Kindersley Limited 2009