PROBLEM: Peeling from Concrete Floors

CAUSE: Concrete floors present numerous potential adhesion problems for coatings. Concrete is a highly alkaline material which reacts chemically with oil or alkyd based finishes to weaken their adhesive bond. Concrete also transmits moisture bringing soluble salts, to the surface (efflorescence). This will gradually generate a sandy or dust-like condition at the surface. Grade level or sub-surface floors are continually subjected to moisture penetration. All concrete should be cast over a vapor barrier. Sub-surface concrete should also be cast over a generous level of gravel with further means to remove water when conditions are severe. Moisture is the primary cause for adhesion failure. Other possible causes include hard-troweled concrete which presents a physical barrier to adhesion by not permitting penetration of coatings. Older concrete can become crumbly, and accumulations of grease or oil create a barrier limiting adhesion.

SOLUTION: Remove paint by scraping and sanding. Clean floor by scrubbing with hot water and a strong detergent solution. Avoid mild dishwashing detergents. These contain skin softening ingredients which interfere with paint adhesion. It may be necessary to use chemical stripper, if the above procedure fails to remove the paint. Follow the directions carefully. Floors that have been subjected to long term oil and grease must be aggressively scrubbed with a grease dissolving compound, such as Benjamin Moore M83 Industrial Maintenance Oil and Grease Emulsifier. Follow the label directions carefully. In all cases, rinse the floor thoroughly. Allow the surface to dry for several days. The next step, called etching, requires protective goggles, boots and rubber gloves to be worn during the process. Mop on 10% solution of muriatic acid and water on clean floor.

ALWAYS MIX ACID INTO THE WATER, NEVER MIX WATER INTO ACID. Allow solution to remain on surface until bubbling ceases (10 to 15 minutes). Flush surface with water and dry completely. When floor is properly etched, it should resemble texture of fine sandpaper. Etching neutralizes the alkaline surface and provides a better bond. It also helps remove salt deposits (called laitance) that can occur on concrete surfaces. Sand off any crumbly areas of loose concrete. The floor should now be ready to paint.

PROBLEM: Peeling from Masonry and Brick

CAUSE: A common cause of peeling on surfaces composed of mortar, brick, building block or concrete is efflorescence, where soluble salts are present. When dissolved by water, they are carried to the surface and remain after the water has evaporated. These salts can push paint away from the surface and peeling results. Efflorescence occurs on brick walls of new construction. A common building practice is to treat new brick or concrete with muriatic acid, rinsing with water to clean away excess mortar. Rinsing removes only those salts on or near the surface. After painting, salts remaining within the bricks will absorb the moisture and travel to the surface, causing peeling. Peeling can also occur when alkyd or oil paint is applied over unetched concrete. Alkyd resins that come in contact with an alkaline surface form a soap film between the concrete surface and the coating, called saponification. This will cause softness and loss of adhesion of the alkyd coating.

SOLUTION: If efflorescence is evident, it must be removed before repainting. First, remove all flaking or chalking paint from the damaged area by wire brushing or sandblasting. If necessary, try applying a solution of 5% muriatic acid or undiluted vinegar. Rinse with clean water. Fill all cracks with masonry patching compound, latex concrete patch, or caulking compound. If the surface is very porous, apply an alkali-resistant primer or block filler. Cover with latex house paint. To prevent recurrence of efflorescence on interior walls, the exterior walls should be sealed. NOTE: Extraneous water sources must be removed before painting (e.g. migration at ground level, often caused by poor drainage).

PROBLEM: Peeling From Hardboard Siding

CAUSE: Hardboard siding is reconstituted natural wood. It is fabricated by reducing natural wood to fibers, adding resins, and then pressing the fibers together into panels. It can be either tempered or standard. Tempered board is denser and has a higher moisture resistance. Standard hardboard should not be used outdoors in areas where it will be directly exposed to the weather. Peeling is often due to poor maintenance of the coated surface. It generally originates at butt joints and drip edges. Water contact directly with bare hardboard in these areas eventually penetrates into the board to repeatedly permeate and expand the compressed wood fibers in the board. The swelling process is irreversible, resulting in delamination of both the paint film and the board.

SOLUTION: Whether supplied bare or factory primed, hardboard must be primed. All joints or bare edges must be primed and caulked to avoid contact with water. Coated hardboard surfaces require regular maintenance to detect possible areas of deterioration or cracking before board failure occurs on a large scale. Where cracking or peeling is observed, it MUST be scraped and sanded immediately, then primed, caulked if necessary, and topcoated. All loose paint must be removed, and the edges of the areas of good paint should be sanded smooth.

PROBLEM: Peeling From Mill-Glazed Western Red Cedar or Redwood Siding

CAUSE: Mill-glaze occurs on smooth, flat-grained western red cedar and occasionally on redwood. Controversy exists over the exact cause of this condition, but the general belief is that it occurs as a result of planing and/or drying the lumber. During the milling or planing process, overheating of the flat- grained smooth siding may bring water soluble resins to the surface creating a hard, varnish-like glaze.

SOLUTION: If the surface is unpainted, it is advisable to roughen smooth siding slightly prior to priming. Two coats of primer may be necessary where severe staining exists. A waiting period of 24 hours after application of first primer coat is recommended before applying second coat and/or finish coat. Tannic acid stains will penetrate first coat of primer leaving brownish streaks or rings. Refer to "Cedar Stain" for additional information. If stains do occur, reprime stained spot and dry thoroughly before applying finish coat. For repainting over mill glaze problem areas, remove the failed coating areas by pressure washing or hand scrapping. Sand and prime as recommended above. Newly installed siding should be sanded and primed as soon as possible. Ultraviolet rays from the sun tend to degrade the integrity of the wood's surface. A 50% loss in adhesion occurs on western red cedar weathered for 16 weeks prior to finishing. Bare weathered siding should be sanded prior to coating to remove loose, dead wood fibers caused by extended exposure.

PROBLEM: Peeling From Asbestos Shingles

CAUSE: After years of wear, asbestos cement siding can develop a surface layer of fine dust similar to chalk causing paint to peel.

SOLUTION: CHECK FOR LOCAL OR STATE REGULATIONS REGARDING THE REMOVAL OF ASBESTOS CONTAINING PRODUCTS BEFORE TRYING TO CURE THIS PROBLEM! Loose paint should be removed by pressure washing. Use extreme caution when scraping or sanding asbestos shingles. It is extremely important to wear protective gear to prevent inhaling asbestos dust particles. It is equally important to prevent fibers and dust from entering occupied areas and to prevent accumulations of dust being left for tracking into these areas. After the shingles have completely dried, check for structural integrity. If they remain soft, no coating will offer long term service.

PROBLEM: Lap Marks

CAUSE: Lap marks sometimes occur when wet and dry layers overlap during application of paint or stain. This nonuniform appearance can be caused by: working too long in one area when painting; too much heat or draft during application; too porous a surface; or the use of an improper thinner. Too much heat or draft causes a rapid loss of solvent or water and speeds up the set time, resulting in a thicker film wherever overlapping occurs.

SOLUTION: Another coat of paint, spread uniformly, is necessary to cover lap marks. If the finish coat is relatively transparent or the surface is overly porous, a second coat or a primer coat may be necessary. To avoid lap marks, do not paint one section of a large area from top to bottom completely. Instead, paint in small enough sections to maintain a wet edge. (Top to bottom painting is appropriate on shingle surfaces since they provide natural breaking points.) Painting on hot, windy days accelerates drying time. Avoid painting under these conditions. Add thinner sparingly if it is needed.

PROBLEM: Uneven Gloss

CAUSE: Surfaces with varying porosity may, after painting appear nonuniform in sheen. This problem is sometimes referred to as "flashing". Uneven application can result in varying film thicknesses that may cause uneven gloss. Fog-strike or moisture on the paint film during drying can locally also affect gloss. Uneven gloss may also be caused by an unsealed porous surface. In this case, a primer-sealer is necessary to prepare the surface. Areas surrounding nail heads and wall studs tend to retain gloss because metal conducts heat and speeds up drying time. In addition, painting over a paint film that is not thoroughly dry or that is too soft can cause uneven gloss.

SOLUTION: If the surface is extremely porous, a prime coat is necessary. Otherwise, another finish coat, spread uniformly, should correct the problem. Some unevenness can be expected on rough surfaces, but additional coats tend to give better uniformity. If moisture contact has caused flatting or if temperature variation has occurred, apply another coat of paint when moisture is not present and/or when changes in temperature are less likely. If the undercoat was not dry, allow the flatted paint to dry hard and apply another finish coat.  

PROBLEM: Poor Hiding Of Colors

CAUSE: Possible causes of poor hiding include over-extended spreading, a radical color change, uneven application, excessive thinning, or inadequate mixing of paint. Certain colors such as yellow, red, and orange tones inherently offer weaker hiding.

SOLUTION: Most paints are designed to be applied as received. Thinning, if necessary, should be at a minimum. An additional coat of the same material and color, applied with a good quality tool at the recommended spreading rate, will usually provide good hiding. The exceptions are extreme color changes, extremely porous surfaces, and certain deep, clear colors. These require a prime coat tinted to the approximate color of the finish coat. Benjamin Moore color chips and color cards use a triangle symbol to identify deep, clear colors in the Moor-O-Matic III system that require a tinted deep base primer to obtain good hiding. Don't forget to follow your dealer's recommendation for type and size of applicators and purchase good quality tools.  

PROBLEM: Peeling From Plaster Walls

CAUSE: Paint peeling from plaster could be the result chalking of the surface. This chalking can be caused by alkali, moisture, or insufficient wet troweling of the white coat. Another reason for peeling is the presence of a glue size (from removed wallpaper), which absorbs water, underneath the paint.