EXPERT ADVICE

How to Prep Surfaces for Painting

Paint preparation is a must. A properly prepared surface is clean, solid and dry, without cracks and imperfections. Whether you're prepping drywall for paint or painting over old paint to revitalize your space, it's the key to good-looking, long-lasting results. Here's how to prep a variety of surfaces before you apply paint.

Interior Paint Prep

Before you paint the entire space, it's a good idea to test the paint you plan to use. Prepare, prime (if necessary) and paint an inconspicuous spot. Wait the appropriate drying time as specified on the label, then look for any adhesion or compatibility problems before proceeding with a full-scale application.

Bare Wood

  1. Fill nail holes, joints and cracks with patching paste.
  2. Sand smooth and remove sanding dust with a tack cloth.
  3. Prime all bare wood and patched areas.
  4. Finish with an easy-to-clean latex semi-gloss or gloss topcoat.

New Plaster Walls

  1. Plaster must be clean and completely cured before prepping surface.
  2. Treat textured, soft, porous or powdery plaster with a solution of one pint household vinegar in one gallon of water. 
    1. Repeat until surface is hard, rinse with clear water and allow to dry.
  3. Dilute your primer with 10% water and then apply to the wall and let dry.
  4. Finish with a latex topcoat.

New Dry Wall

  1. Panels must be securely nailed or glued in place.
  2. All panel joints must be taped and filled before painting.
  3. When joint cement and/or patching materials are thoroughly dry, sand smooth, wipe away dust, then prime.
  4. Finish with a latex topcoat.

Wallpaper

  1. Always remove wallpaper before painting. Use a chemical wallpaper remover or rent a steamer, if necessary.
  2. Once the paper is removed, wash off old adhesive. Rinse with water and allow the wall to dry before priming.

Previously Painted Surfaces

  1. Wash off dirt, grease, soap and oil buildup with the appropriate cleaner and rinse thoroughly.
  2. Remove loose paint and powdery substances.
  3. Patch holes and cracks with spackling or patching compound. Allow to dry, then sand smooth.
  4. For glossy or nonporous surfaces, lightly sand to a dull finish or use an abrasive cleanser. 
  5. Remove sanding dust or cleanser residue.
  6. Prime all bare areas prior to applying topcoat. This will avoid "spot priming," which can result in a non-uniform appearance between primed and non-primed areas.

Tip: Seal stains (such as water, smoke, ink, pencil or grease stains) with PrepRite ProBlock® Primer/Sealer.

Exterior Paint Prep

For exterior surfaces, don't paint immediately after rain (or if rain is predicted), during foggy weather or when the temperature is below 50 degrees Fahrenheit, unless you're using products specifically designed for these conditions.

Painted Wood, Plywood, Composition Board

  1. Sand any exposed wood to a fresh surface.
  2. Patch all holes and imperfections with a wood filler or putty and sand smooth.
  3. Prime any patched areas.

Masonry, Concrete, Cement, Block

  1. All new surfaces must be cured according to the supplier's recommendations before prepping, usually about 30 days. If painting cannot wait 30 days, allow the surface to cure 7 days and then prime.
  2. Remove all form release and curing agents.
  3. Fill rough surfaces to provide a smooth surface.
  4. Repair cracks, voids, and other holes with patching or sealant.

Aluminum & Galvanized Steel

  1. Wash to remove any oil, grease or other surface contamination.
  2. Remove corrosion with sandpaper, steel wool or other abrading method.

Steel

  1. Remove rust and mill scale with sandpaper, steel wool or other abrading method.
  2. Prime any bare areas the same day the surface was cleaned.

Vinyl Siding

  1. Clean the surface by scrubbing with warm, soapy water, then rinse throughly.
  2. Do not paint vinyl siding with a color darker than the original color. Painting with darker colors may cause the siding to warp.

Warning! Removal of old paint by sanding, scraping or other means may generate dust or fumes that contain lead. Exposure to lead dust or fumes may cause brain damage or other adverse health effects, especially in children or pregnant women. Controlling exposure to lead or other hazardous substances requires the use of proper protective equipment, such as a properly fitted respirator (NIOSH approved) and proper containment and cleanup. For more information, call (in the U.S.) the National Lead Information Center at 1-800-424-LEAD or contact your local health authority.

Sherwin-Williams Primers

Explore our range of primers designed to meet the challenges of specific surfaces.