back Follow these steps to prepare the wall surface for painting. 1) Cleaning
Take time to dust and vacuum all surfaces first. Then wash the walls with soap and water, especially in kitchens and bathrooms. If there are little gray-green dots of mold, add up to a quart of bleach to 3 quarts of an ammonia-free detergent solution. Protect nearby floors with newspapers and drop cloths. Allow the bleach solution to remain on the wall for 15 minutes, and then rinse thoroughly. 2) Smoothing Surfaces
Paint won't hide imperfections - in fact, it accentuates them, making any previously unnoticed bumps or dents stand out. To avoid surprises, shine a bright light at a low angle across the surface to spot problem areas before you begin to paint.
Scrape any cracked or flaking areas with a paint scraper until you reach paint that is solidly fixed on the wall. (Fig. 1)
Where the paper surface of drywall is torn, trim the tear free with a utility knife, and apply joint compound over the damage. (Fig. 2) Use a wide blade to fill large bare patches with joint compound. Apply several thin coats instead of one thick layer. Use a power palm sander or a sanding block to smooth the patches. Oversanding can scuff the drywall surface. (Fig. 3) 3) Sealing Over Stains
Remove surface stains as best you can with a detergent/water solution or an appropriate solvent/spot remover.
To prevent remaining discoloration from bleeding through, seal the area with a stain-killing primer, such as pigmented white shellac, which has tremendous hiding power and also makes a good primer on metal (Fig. 4). These sealers dry fast and won't slow you down. Similarly, coat knots in paneling or trim so that resins won't bleed through. 4) Priming
Prime all repaired areas, following the paint manufacturer's recommendations for priming. Some surfaces, such as unpainted wood, require primer with certain paints but not others. Failure to use a primer will reduce paint adhesion and lead to flaking and peeling paint.
Previously painted walls and ceilings generally do not require a primer unless you plan a radical color change (such as white over red) or you have stains to cover. But if you've patched with joint compound, the unpainted compound will absorb paint differently than surrounding painted areas, leaving a blotchy finish. Although you can usually apply two topcoats, it's better to use a less-expensive primer, perhaps tinted to a similar color as the top coat, covered by one top coat. (Fig. 5) 1) Heat it Up
Use a heat gun to gradually soften layers of paint. Work on one small area at a time, and keep the gun nozzle moving. (Fig. 6) 2) Scrape it Off
Use a stiff scraper to remove layers of paint heated by the gun. Use a razor-edge scraper to clear grooves in molding. more... | 
