Common Paint Problems & Solutions
Peeling From Masonry or Brick
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.
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).
Peeling From Hardboard Siding
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.
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.
Peeling From Mill-Glazed Western Red Cedar or Redwood Siding
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.
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 with an alkyd or latex primer. 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.
Peeling from Asbestos Shingles
After years of wear, asbestos cement siding can develop a surface layer of fine dust similar to chalk causing paint to peel.
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. Sound substrate should be primed with an alkyd or latex primer.
Poor Galvanized Metal Adhesion
• Improper surface preparation.
• Failure to apply a primer before application of an oil-based paint.
• Failure to sand baked-on enamel finishes or glossy surfaces before painting.
Any rust on the metal should be removed with a wire brush; then, an acrylic latex corrosion-resistant primer should be applied (one coat is usually sufficient). New or previously painted galvanized metal that is completely rust-free should be cleaned to remove all fabricating oils, then can be painted with a top quality acrylic latex paint without applying a primer; however, a metal primer should always be applied to unpainted galvanized metal before applying an oil-based or vinyl latex top coat.
Stains from red cedar, cypress, and redwood are due to a combination of moisture and insufficient sealing. Moisture carries water-soluble color extracts (tannic acid) contained in the wood through paint films. Staining is more likely to be visible when light or medium colors are used. It occurs more frequently with a latex coating than a solvent or oil based coating.
Solution for Unpainted Wood:
If staining occurs during paint application, use two coats of primer before topcoating. A waiting period of 24 hours after application of the first primer is recommended before applying the second coat and/or finish coat. Tannic acid stains will penetrate the first coat of primer leaving brownish streaks or rings. If stains do occur, reprime the stained spot, allow to dry and apply the finish coat. Sometimes it is best for the new wood to weather for several weeks prior to painting.
Solution for Previously Painted Surfaces:
Stained areas can be washed with a one-to-one mixture of denatured alcohol and water. Wood bleach (oxalic acid) can also be used. Rinse treated areas well, let dry, then apply one coat of desired primer and topcoat.
Wax Bleeding on Hardboard Siding
A cause of discoloration seen on painted hardboard siding is "wax bleed". Wax or petrolatum is used in the manufacture of hardboard siding to make it moisture resistant. Wax can migrate to the surface. Once on the surface, wax can change the appearance of a coating by its "wetting" effect or its tendency to increase dirt retention. Contributing factors include: 1. Dark paints exhibit discoloration more readily due to a tendency to absorb heat. 2. Areas lacking adequate coats are more likely to stain. This appears as irregular discoloration on brushed or rolled surfaces where wax bleeding occurs in valleys or thin areas in the application pattern. 3. Paints containing low levels of binder are more porous and are more likely to allow wax migration from hardboard. 4. Exposures subjected to direct sun and heat will accelerate wax bleed.
In order to correct a situation where discoloration exists, one must first identify the problem as wax bleed. Do the following:
Place a few drops of household bleach on the discolored area. If there is no whitening or bleaching on the surface, the stain is probably wax.
Place water droplets on both normal and discolored areas. If the water beads up and runs off, a wax film is likely.
Clean discolored areas with detergent solution if surface wax is light. In severe cases, surface must be thoroughly cleaning by wiping with rags wet with a solvent such as mineral spirits. Change rags frequently and allow surface to dry before painting.
Blistering refers to the formation of a blister caused by vapor expanding between the coated surface and the film. Due to humidity, construction defects, or lack of effective vapor barriers, moisture condenses on or saturates wood siding. Lower humidity and high temperature generate pressures within wood and on adhesive bond of the coating as trapped moisture evaporates. Solvent based coatings are most susceptible. Fresh blisters are filled with water. As the surface dries, water evaporates, but the paint film does not recover. Blistering is accelerated by the swelling effect of moisture on wood. Continued swelling and contraction between day and night humidity and temperature variations weakens adhesion. Another cause is solvent entrapment, or painting with solvent based coatings in direct sunlight on a surface that is too warm. This problem is prevalent in darker colors, due to absorption of heat, more than light colors. Thicker application or recoating prior to complete cure of a previous coat contribute to this type of failure. Under this condition, the paint surface dries before all the solvent is released from the underlying film. Expansion of trapped solvent produces blisters.
If blistering was caused by moisture, a number of solutions exist. Repair loose caulking and install vents or exhaust fans. If the home has lap siding, install siding vents. Vents or fans allow moisture from in the house to evaporate before penetrating wood siding. This will minimize future blistering problems. Sand and scrape peeling paint to bare wood. Prime exposed areas and repaint. If large areas of paint have blistered and need to be removed, high pressure washing or use of a heat gun will speed the process. Heat blisters develop in FRESHLY applied coatings only. When broken, they don't contain liquid and are not associated with a surface defect that requires remediation. These blisters may be removed by scraping and sanding. The surface should be recoated under more favorable conditions.
Lap marks sometimes occur when wet and dry layers overlap during application of paint or stain. This nonuniform appearance can be caused by: too much heat or draft during application; painting exterior in direct sun; 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.
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.
All latex paints contain detergent-like materials called surfactants which are necessary for the stability of the paint formulation. In cases where surfactant is leaching from the dried film, this material will dissipate in small amounts. They tend to come out of the film slowly and are easily removed by normal weathering. Under certain curing conditions, such as low temperatures, condensing moisture, etc., this leaching process occurs rapidly and results in a surfactant build-up on the surface. Leached surfactant can appear as a thick brown syrup-like deposit or rundown. On occasion it may assume a white crystalline form. Surfactant leaching is not limited to exterior coatings - it may appear in bathrooms or other areas where moisture condenses on walls. In these instances, a clear amber glossy rundown will be visible.
Most often, weathering removes the visible film of surfactant from the surface. The sheen and the color are restored. However, most accumulations of surfactant are observed in areas protected from natural weathering. In these instances, it can be removed with a fine mist from a garden hose or by light rubbing with a wet cloth. Often the best solution is to do nothing and let nature take its course. The surfactant will do no harm and time will correct the problem. Surfactants must be removed prior to painting.
• Forms most often on areas that tend to be damp, and receive little or no direct sunlight (walls with a northerly exposure and the underside of eaves are particularly vulnerable.)
• Use of a lower quality paint, which may have an insufficient amount of mildewcide.
• Failure to prime bare wood before painting.
• Painting over a substrate or coating on which mildew has not been removed.
Test for mildew by applying a few drops of household bleach to the discolored area; if it disappears, it is probably mildew. Remove all mildew from the surface by scrubbing with a diluted household bleach solution (one part bleach, three parts water); wear rubber gloves and eye protection. Power washing is also an option, however the bleach solution must still be used. Rinse thoroughly, prime any bare wood, then apply one or two coats of top quality exterior paint, which typically contains more mildewcide.
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.
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.
Poor Hiding of Colors
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.
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 colorst hat require a tinted deep base primer to obtain good hiding. Don't forget to follow your retailer's recommendation for type and size of applicators and purchase good quality tools.
Peeling From Plaster Walls
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. Plaster being an older substrate, cracking and peeling may be caused by an excessive paint build up.
New plaster should be primed AFTER 30 days curing. This will allow for reduction in moisture and alkali content. After curing and before priming, the plaster should be wiped with a damp cloth to remove powder and dust. Peeling areas should be scraped down to a sound surface. Smooth the scraped edges with sand paper. If peeling is severe, then all the paint should be removed. Otherwise the remaining coating will peel, thus causing the new coat to fail. Cracks and holes in plaster should be repaired before repainting. If patching is necessary, a water-mix patch should be used when the intended topcoat is latex. Oil based patching compounds sometimes bleed into latex. When using a water-mix patch, thoroughly dampen the surrounding edges of the damaged areas to prevent the plaster from absorbing moisture and becoming crumbly. If the surface is badly disintegrated, mount canvas or "hardboard" over the plaster. Apply primer before and after filling cracks and holes. Sand when dry. Generally an alkyd primer performs best.
Picture Framing on Drywall (a.k.a. Hatbanding)
Hatbanding is caused by excessive cutting-in of the walls, corners, trim and ceiling areas with a brush or by rolling walls with an excessively long nap roller cover, thereby producing a heavy textured application when compared to brush applied cut-in areas. It may also be caused when applying a wet finish coat onto areas that are already dry.
Feather-edge brushing of the finish coat when cutting- in of the areas to be painted produces a coat of paint that is approximately the same thickness as the coat applied later with a roller. The brush should leave a thin, feathered edge of paint that will merge into a smooth layer of new paint. By doing this, problems of the finish coat (i.e., hatbanding) are reduced. When rolling on smooth surfaces (i.e., drywall), use roller covers ranging from 1/4" to 1/2" nap, depending on the sheen of the finish coat to be applied. When rolling into surfaces that have been previously cut-in with a brush, turn roller sideways (rotate 90 degrees on the wall) and apply a thin coat of finish, rolling into the previously cut-in areas. Make sure to roll the finished coat back into the drying paint. Properly primed drywall reduces the occurrence of hatbanding.
Peeling from Concrete Floors
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 and poor surface preparation are the primary causes 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.
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.
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.
On-screen & printer color representations may vary from actual paint colors.
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