Painting Walls: Wall Preparation Tips

By Howard Stier

Preparing walls for painting is the most difficult part of the painting process. But if you don't put the time to scrape, patch, sand and prime the walls, your finished project will show it.  So if you want beautiful, glass smooth walls and baseboards, follow these simple preparation tips.

What you'll need

• Vacuum
• Soap and water
• Bleach
• Non-ammonia detergent
• Drop cloths or newspaper
• Flashlight
• Paint scraper
• Joint compound
• Knife and wide blade
• Power palm sander or sanding block
• Solvent or spot remover
• White shellac or stain removing primer
• Primer or tinted primer
• Heat gun (if prepping baseboards)

How to Prep Your Walls:

1)Dust and vacuum all surfaces and for good measure, wash the walls down with soap and water. This is especially important in kitchens and bathrooms.  If you see evidence of mold which appears as gray-green speckles, use a solution of up to a quart of bleach to 3 quarts ammonia-free detergent. (Never mix bleach with ammonia).  Dab the solution on the area and allow to sit for about 10 minutes before rinsing thoroughly.

2)  Cover floors and furniture with newspaper or drop cloths.

3) Smooth the walls. Direct a flashlight across the walls to double check for any problems. For cracks or flaking areas, use a paint scraper until you reach a solid coat of paint beneath. If you find torn drywall, trim the torn piece with a knife and apply joint compound over the damaged area. For large bare patches, use a wide blade to apply joint compound, applying several thin coats instead of a thick coat. Once you have applied the compound and let it dry, smooth it with a palm sander or sanding block. Don't over-sand.

4. Fix surface stains with a detergent/water solution or solvent/spot remover.  If the wall is discolored, you will need to seal the area with a stain-removing primer such as white shellac which also effectively covers knots in paneling or trim and prevents resins from bleeding through.
5. Prime any repaired areas as per the manufacturer’s directions. This step will ensure paint will adhere well and will prevent future peeling. You will need to check recommendations for priming unpainted wood, which may need a different type of primer.  If you are repainting walls or ceilings, you may not need to prime first unless you are making a dramatic color change from a dark to light color, for example, or if you are trying to cover stained areas.  You will need to apply primer to any joint compound repairs to prevent an uneven appearance. Besides, a layer of tinted primer is less expensive than two coats of paint.

6. To prepare the trim, you will also need to lightly sand imperfections.  You may need to take old paint down to the raw wood by stripping, sanding, heating and/or scraping. If the paint was applied before the late 1970s, you need to test for lead before removing.

You'll need a heat gun to scrape off old baseboard paint. Keep the nozzle of the gun moving across the surface while you scrape it with a stiff scraper. A razor-edge scraper can be used to clear grooves in molding.