Exterior Surface Preparation Guidelines

The best paint we make will not perform as intended if applied over a poor surface. Clean and dry, glossy surfaces dulled, stains, mildew and other contaminants removed all are critical to optimal paint performance.

If there is one absolute guarantee with paint it's that it will fail if not applied to a properly prepared surface.

The information listed here will give you a detailed guide to making sure your paint project works. They are not intended to be all inclusive as each paint project can have unique situations that need to be addressed to insure a good paint job.

If you can't find an answer to your needs here, please email "Ask the Pro" or call 800-383-8406 and we'll make sure you get the answers you need.

Wood - New
      To Be Painted
      To Be Stained
   Previously Finished
      To Be Painted
      To Be Stained

Hardboard Siding - New
      To Be Painted
    Previously Finished
      To Be Painted

Cementitious Panels / Siding New
      To Be Painted
   Previously Finished
      To Be Painted

Concrete / Masonry - New
      To Be Painted
   Previously Finished
      To Be Painted

CMU (Concrete Masonry Unit, Cinder Block) - New
      To Be Painted
   Previously Finished
      To Be Painted

Gypsum Board (Drywall, Sheetrock) New
      To Be Painted
   Previously Finished
      To Be Painted

Ferrous Metal (Steel, Iron) - New
      To Be Painted
   Previously Finished
      To Be Painted

Non-Ferrous Metal (Aluminum, Galvanized) - New
      To Be Painted
   Previously Finished
      To Be Painted

Each system will have a link (Top) to return to the beginning of this page.

Wood - New (Top)
To Be Painted

Wood - New (Top)
To Be Stained

Wood - Previously Finished (Top)
To Be Painted

(*NOTE: If lead is suspected in the original paint, do not attempt to remove paint or scrape, sand, use heat gun, etc., which might release lead into the environment, rather contact a contractor qualified for lead paint assessment and abatement.)
1. If mildew is present or suspected treat with a 3:1 water and household bleach solution, leaving it on for 20 minutes and adding more as it dries. Wear eye and skin protection. Rinse thoroughly and let dry.
2. Remove any dirt and contaminants by high pressure water blast. Water pressure should not exceed 2,500 psi to help prevent damage to the wood surface.
3. Dull any glossy areas with fine (220) grit sandpaper. Wear eye protection, dust mask and work gloves.
4. Fill any gouges with an exterior, non-shrinking patching compound; let dry and sand flush.
5. Fill gaps (1/8” to 1/4”) with a quality acrylic or siliconized acrylic caulk, and immediately smooth it flush. Allow to dry over night and make a second application if needed. Do not sand caulk applications.
6. Gaps larger than 1/4” should be prefilled with foam backer rod prior to application of a quality acrylic or siliconized acrylic caulk.

Wood - Previously Finished (Top)
To Be Stained

Hardboard Siding - New (Top)
To Be Painted

Hardboard Siding - Previously Finished (Top)
To Be Painted

Cementitious Panels / Siding New (Top)
To Be Painted

1. If mildew is present or suspected treat with a 3:1 water and household bleach solution, leaving it on for 20 minutes and adding more as it dries. Wear eye and skin protection. Rinse thoroughly and let dry.
2. Remove any dirt and contaminants by high pressure water blast. Water pressure should not exceed 2,500 psi to help prevent damage to the wood surface.
3. Fill any gouges with an exterior, non-shrinking patching compound; let dry and sand flush.
4. Fill gaps (1/8” to 1/4”) with quality acrylic or siliconized acrylic caulk, and immediately smooth it flush. Allow to dry over night and make a second application if needed. Do not sand caulk applications.
5. Gaps larger than 1/4” should be prefilled with foam backer rod prior to application of a quality acrylic or siliconized acrylic caulk.
6. All nail heads should be counter sunk and filled with quality acrylic or siliconized acrylic caulk, and immediately smooth it flush. Allow to dry over night and make a second application if needed. Do not sand caulk applications.

Note: New siding and panels supplied from the manufacturer pre-primed should be considered un-primed if exposure to the elements exceeds 90 days. Factory applied primers are commonly applied at very thin dry film thickness and are intended to protect the surface for a minimal time prior to installation.

Cementitious Panels / Siding Previously Finished (Top)
To Be Painted

Concrete / Masonry - New (Top)
To Be Painted

1. If mildew is present or suspected treat with a 3:1 water and household bleach solution, leaving it on for 20 minutes and adding more as it dries. Wear eye and skin protection. Rinse thoroughly and let dry.
2. New concrete and masonry, depending on temperature and humidity, requires a minimum of 30 days to dry to insure surface alkalinity is acceptable. The PH should be between 6 and 9 prior to paint application.
3. Remove any loose or protruding masonry excess by a stiff scraper. (A hammer may be necessary to chip hardened areas.)
4. Fill any gouges with exterior cement / concrete patch; let dry and sand flush.
5. Fill gaps (1/8” to 1/4”) with quality acrylic or siliconized acrylic caulk, and immediately smooth it flush. Allow to dry over night and make a second application if needed. Do not sand caulk applications.
6. Gaps larger than 1/4” should be prefilled with foam backer rod prior to application of a quality acrylic or siliconized acrylic caulk.

Concrete / Masonry - Previously Finished (Top)
To Be Painted

(*NOTE: If lead is suspected in the original paint, do not attempt to remove paint or scrape, sand, use heat gun, etc., which might release lead into the environment, rather contact a contractor qualified for lead paint assessment and abatement.)
1. If mildew is present or suspected treat with a 3:1 water and household bleach solution, leaving it on for 20 minutes and adding more as it dries. Wear eye and skin protection. Rinse thoroughly and let dry.
2. Remove any dirt and contaminants by high pressure water blast. Water pressure should not exceed 2,500 psi to help prevent damage to the surface.
3. Dull any glossy areas with medium (120) grit sandpaper. Wear eye protection, dust mask and work gloves.
4. Fill any gouges with exterior cement / concrete patch; let dry and sand flush.
5. Fill gaps (1/8” to 1/4”) with quality acrylic or siliconized acrylic caulk, and immediately smooth it flush. Allow to dry over night and make a second application if needed. Do not sand caulk applications.
6. Gaps larger than 1/4” should be prefilled with foam backer rod prior to application of a quality acrylic or siliconized acrylic caulk.

CMU (Concrete Masonry Unit, Cinder Block) - New (Top)
To Be Painted

1. If mildew is present or suspected treat with a 3:1 water and household bleach solution, leaving it on for 20 minutes and adding more as it dries. Wear eye and skin protection. Rinse thoroughly and let dry.
2. New concrete and masonry, depending on temperature and humidity, requires a minimum of 30 days to dry to insure surface alkalinity is acceptable. The PH should be between 6 and 9 prior to paint application.
3. Remove any dirt and contaminants by high pressure water blast. Water pressure should not exceed 2,500 psi to help prevent damage to the surface.
4. Remove any loose or protruding masonry excess by a stiff scraper or wire brush.
5. Fill any gouges with exterior cement / concrete patch; let dry and sand flush.
6. Fill gaps (1/8” to 1/4”) with quality acrylic or siliconized acrylic caulk, and immediately smooth it flush. Allow to dry over night and make a second application if needed. Do not sand caulk applications.
7. Gaps larger than 1/4” should be prefilled with foam backer rod prior to application of a quality acrylic or siliconized acrylic caulk.

CMU (Concrete Masonry Unit, Cinder Block) - Previously Finished (Top)
To Be Painted

(*NOTE: If lead is suspected in the original paint, do not attempt to remove paint or scrape, sand, use heat gun, etc., which might release lead into the environment, rather contact a contractor qualified for lead paint assessment and abatement.)
1. If mildew is present or suspected treat with a 3:1 water and household bleach solution, leaving it on for 20 minutes and adding more as it dries. Wear eye and skin protection. Rinse thoroughly and let dry.
2. Remove any dirt and contaminants by high pressure water blast. Water pressure should not exceed 2,500 psi to help prevent damage to the surface.
3. Dull any glossy areas with medium (120) grit sandpaper. Wear eye protection, dust mask and work gloves.
4. Fill any gouges with exterior cement / concrete patch; let dry and sand flush.
5. Fill gaps (1/8” to 1/4”) with quality acrylic or siliconized acrylic caulk, and immediately smooth it flush. Allow to dry over night and make a second application if needed. Do not sand caulk applications.
6. Gaps larger than 1/4” should be prefilled with foam backer rod prior to application of a quality acrylic or siliconized acrylic caulk.

Gypsum Board (Drywall, Sheetrock) New (Top)
To Be Painted

1. If mildew is present or suspected the best option is to replace the gypsum board.
2. Remove any dirt by stiff broom or compressed air. Wear eye protection, dust mask and work gloves.
3. Following application of tape joint compound sand joints to achieve the smoothness required using either drywall sanding screens and/or sand paper.
4. Fill any gouges with an exterior, non-shirnking patching compound; let dry and sand flush.
5. Fill gaps (1/8” to 1/4”) with non-shrink spackle and immediately smooth it flush. Allow to dry over night and make a second application if needed.
6. Gaps larger than 1/4” should be cut out and patched with scrap gypsum board followed by the required taping and joint compound.

Gypsum Board (Drywall, Sheetrock) Previously Finished (Top)
To Be Painted

(*NOTE: If lead is suspected in the original paint, do not attempt to remove paint or scrape, sand, use heat gun, etc., which might release lead into the environment, rather contact a contractor qualified for lead paint assessment and abatement.)
1. If mildew is present or suspected treat with a 3:1 water and household bleach solution, leaving it on for 20 minutes and adding more as it dries. Wear eye and skin protection. Rinse thoroughly and let dry.
2. Remove any dirt by scrubbing with detergent and water. Rinse thoroughly and let dry.
3. Dull any glossy areas with medium (120) grit sandpaper. Wear eye protection, dust mask and work gloves.
4. Fill gaps (1/8” to 1/4”) with quality acrylic or siliconized acrylic caulk, and immediately smooth it flush. Allow to dry over night and make a second application if needed. Do not sand caulk applications.
5. Gaps larger than 1/4” should be cut out and patched with scrap gypsum board followed by an exterior, non-shirnking patching compound; let dry and sand flush.

Ferrous Metal (Steel, Iron) - New (Top)
To Be Painted

1. Remove any dirt, grease and other contaminants by high pressure water blast.
2. Remove rust scale and/or rust staining by means of hand tool cleaning and /or power tool cleaning. Wear eye protection, dust mask and work gloves.
3. Grind any weld slag, metals burrs and other metal protrusions to smooth the surface using power tool cleaning.
4. High performance coating systems may require using SSPC-SP-5/NACE No. 1*, white metal blast cleaning, SSPCSP- 6/NACE No. 3* commercial blast cleaning, SSPC-SP-7/NACE No. 4* brush off blast cleaning or SSPC-SP-10/NACE No. 2* near white blast cleaning. Contact the Architectural Services Division at Kwal Paint for specific recommendations.
5. Optionally, a “Rust Converter” solution may be used when flash rust staining is present. Refer the the rust converter manufacturers recommendation for use.

Ferrous Metal (Steel, Iron) - Previously Finished (Top)
To Be Painted

(*NOTE: If lead is suspected in the original paint, do not attempt to remove paint or scrape, sand, use heat gun, etc., which might release lead into the environment, rather contact a contractor qualified for lead paint assessment and abatement.)
1. Remove any dirt by scrubbing with detergent and water. Rinse thoroughly and let dry.
2. Dull any glossy areas with medium (120) grit sandpaper. Wear eye protection, dust mask and work gloves.
3. Optionally a chemical de-glossing agent may be used. Refer the the deglosser manufacturers recommendation for use. Wear eye protection, dust mask and work gloves.
4. Grind any weld slag, metals burrs and other metal protrusions to smooth the surface using power tool cleaning.
5. High performance coating systems may require using SSPC-SP-5/NACE No. 1*, white metal blast cleaning, SSPCSP- 6/NACE No. 3* commercial blast cleaning, SSPC-SP-7/NACE No. 4* brush off blast cleaning or SSPC-SP-10/NACE No. 2* near white blast cleaning. Contact the Architectural Services Division at Kwal Paint for specific recommendations.
6. Optionally, a “Rust Converter” solution may be used when flash rust staining is present. Refer the the rust converter manufacturers recommendation for use.

Non-Ferrous Metal (Aluminum, Galvanized) - New (Top)
To Be Painted

1. Remove any dirt, grease and other contaminants by high pressure water blast.
2. Optionally, a “Conversion Coating” may be used to prepare the substrate for coating application. Refer the the conversion coating manufacturers recommendation for use.
3. Grind any weld slag, metals burrs and other metal protrusions to smooth the surface using power tool cleaning.
4. High performance coating systems may require using SSPC-SP-5/NACE No. 1*, white metal blast cleaning, SSPCSP- 6/NACE No. 3* commercial blast cleaning, SSPC-SP-7/NACE No. 4* brush off blast cleaning or SSPC-SP-10/NACE No. 2* near white blast cleaning. Contact the Architectural Services Division at Kwal Paint for specific recommendations.

Non-Ferrous Metal (Aluminum, Galvanized) - Previously Finished (Top)
To Be Painted

(*NOTE: If lead is suspected in the original paint, do not attempt to remove paint or scrape, sand, use heat gun, etc., which might release lead into the environment, rather contact a contractor qualified for lead paint assessment and abatement.)
1. Remove any dirt, grease and other contaminants by high pressure water blast.
2. Remove flaking and loose existing paint by means of hand tool cleaning and /or power tool cleaning. Wear eye protection, dust mask and work gloves.
3. Dull any glossy areas with medium (120) grit sandpaper. Wear eye protection, dust mask and work gloves.
4. Optionally a chemical de-glossing agent may be used. Refer the the deglosser manufacturers recommendation for use. Wear eye protection, dust mask and work gloves.
5. Grind any metals burrs and other metal protrusions to smooth the surface using power tool cleaning.
6. High performance coating systems may require using SSPC-SP-5/NACE No. 1*, white metal blast cleaning, SSPCSP- 6/NACE No. 3* commercial blast cleaning, SSPC-SP-7/NACE No. 4* brush off blast cleaning or SSPC-SP-10/NACE No. 2* near white blast cleaning. Contact the Architectural Services Division at Kwal Paint for specific recommendations.

Proper surface preparation is the foundation to a long lasting paint job,

Cleaning, patching and priming are the keys to excellence.