Recent Questions

Q: I have tried everything I can think of to keep paint on exterior window sills. What do you suggest?

A: You should prepare and repaint the entire window unit. Begin by removing all loose paint with a wire brush or scraper. Don't forget the ends and underside of the sill, as peeling or cracking often begins there. Next, remove any old caulking from the joints in the frame and the areas where the frame meets the sill and where the frame and sill meet the siding. Finish the surface prep by sanding the wood until it has a bright, new look. This removes any decayed wood fibers from the surface and provides a sound surface to paint. Now apply one coat of A-100 Exterior Alkyd Wood Primer, again paying special attention to the end grain and underside of the sill. After the primer dries, apply an acrylic latex caulk to the joints in the frame, the space between the frame and sill, and the space between the window and the siding. Follow with two coats of a top-quality acrylic latex satin or gloss house paint, like SuperPaint. After you replace the storm window, make sure the drain holes at the bottom are open. This will prevent the condensation that builds up on the inside of the window from collecting on the sill.

Q: Can mildew be permanently prevented?

A: No. Paints can be formulated to inhibit mildew growth, but under some conditions, mildew eventually will reappear on any type of paint.

Q: One of my customers is experiencing a great deal of peeling under the eaves of his house. Is moisture the culprit or do you think I failed to properly prepare the surface the last time I painted?

A: The eaves of a house are a frequent location for paint problems, with peeling topping the list of concerns. Moisture drawn out of the house sometimes is the source of the problem, but more times than not the culprit is lack of inter-coat adhesion. This occurs when paints are applied to old, hard and glossy paint films and when dirt and contaminants, such as salt, is not properly removed prior to painting.

Q: Why does wood fencing darken significantly when left unprotected?

A: Ultra-violet radiation from the sun causes wood to naturally darken. For wood surfaces that have never been coated, or which have been finished with clear varnishes or lightly pigmented stains, this darkening can be unattractive.

Q: The following day after painting the siding on a house, I noticed wrinkles in various areas of the finish. What went wrong?

A: When paint is applied in excess of the recommended wet film thickness or when two coats of paint are applied too quick. This will not allow sufficient drying and wrinkling may occur. This surface imperfection should be corrected once the paint film has dried by power sanding. The smooth area should then be primed with a quality oil or latex primer prior to topcoating.

Q: After painting an aluminum siding with a latex house paint, there where sections of the house that contained streaks. What happened?

A: When dew forms on latex paints before the film has fully cured, a concentrated residue from the paint material can form on the surface, causing staining, unsightly runs and gloss patterns. This finish problem is known as surfactant leaching. Aluminum siding is particularly prone to surfactant leaching because this type of substrate reacts to temperature changes faster than wood. To avoid this problem, apply paint during temperatures that allow proper curing. Avoid painting during hot and humid days with significantly cooler evening temperatures.

Q: I recently was asked to quote on a re-paint job for a new stucco house with unsightly stain streaks. Do you know what possibly could be causing this?

A: Stucco and mortar joints contain hydrated or "hot" lime, a dry compound added to improve the workability of these materials. If the high alkalinity of mortar, cement mixes and concrete is not addressed prior to painting, a reaction can occur when moisture is present, resulting in blistering, peeling and burning stains.

Q: What causes reddish colored stains on cedar and redwood?

A: The culprit here is a water-soluble dye called tannin. Moisture in the wood will cause the tannin to migrate to the surface and stain the paint. New red-colored wood must be sealed with a quality alkyd or latex undercoater to create a barrier between the topcoat and the wood. More severe cases of tannin bleed may need one or two coats of an alkyd primer to prevent discoloration.

Q: Why do doors painted with latex paint sometimes stick to the weather-stripping?

A: Latex paints contain chemicals called plasticizers that allow proper film formation and keep the coating flexible. Many vinyl and plastic weather-stripping materials also contain plasticizers to give them flexibility. When two surfaces containing plasticizers come in contact with each other, they can have the tendency to stick. This condition, known as blocking, will generally occur during the early curing time of the coating, but it can continue for some time. Blocking can also occur on double-hung windows and garage doors. The easiest way to prevent blocking is to use a non-blocking acrylic, or alkyd base paint in areas where it may occur.

Q: What causes white powdery deposits on masonry surfaces, and how can I fix them?

A: The deposits, known as efflorescence, are caused by moisture in the masonry. The moisture dissolves salts in the masonry -- the mortar, block, concrete, etc. -- and is drawn to the surface by the heat of the sun. The water evaporates, leaving behind white deposits that must be removed before painting. After you find and fix the source of the moisture, remove the efflorescence with a wire brush and coat the surface with a masonry primer and topcoat.

Q: What causes small cracks to form on a recently painted wall?

A: This problem is commonly called "alligatoring." The most common cause of alligatoring is the application of too thick of a paint film. The surface of the film dries first, with the rest of the film taking longer to dry than normal. When the underside of the paint finally does dry, it shrinks, causing the top of the film to pull apart and leaving unsightly cracks. You can prevent this by applying the paint at the manufacturer's recommended thickness and spreading rate. A less frequent cause of alligatoring results from painting over a contaminant on the surface such as oil, silicone, body oils, hair spray, etc. You can prevent this by thoroughly cleaning the surface before painting.

Q: Why after one year am I getting discoloration on some areas of preprimed finger jointed wood-work coated with a latex semi-gloss?

A: The most likely cause of the discoloration is the resin in the glue used to hold the wood together. An alkyd primer applied to the wood before the latex semi-gloss will usually lock this in, but sometimes you need to resort to an alkyd stain killer, or even a pigmented shellac stain killer in severe cases.

Q: After a new home is painted and the wood shrinks along with the caulk, is it normal to need to recaulk and/or repaint before the first year?

A: With the settling you get in a new house and as the wood dries and shrinks, you're bound to have some places that will need touched up with more caulk and paint. Usually after the first year, you won't have any more shrinkage. Make sure you use a good acrylic latex caulk that is flexible and will withstand some movement in the joint.

Q: I recently painted a house with vertical wood siding white, but now notice rust staining from nails. What should I do?

A: If steel nails or uncoated steel hardware is exposed to air or moisture, unsightly stains can develop on adjacent paint surfaces. This problem is easily rectified by sanding the metal clean and applying a rust-preventative primer. Nails should then be countersunk and caulked or wood filled.

Q: On a newly cedar sided house I am painting, I have noticed discoloration of the paint film after the paint dried. What could be causing this to occur?

A: Red-colored woods, such as redwood and cedar, contain a water-soluble dye called tannin. If latex topcoats are applied directly to these wood surfaces, a reddish discoloration may form through the paint finish. Discoloration may also occur on these woods by water migrating to the surface.

Q: What usually causes a coating to fail?

A: The most frequent causes for premature paint failure are as follows: insufficient surface preparation; low film build; improper coating was used; product not applied as directed; or environmental conditions (moisture, fumes, chemicals, etc.).

Q: Why is it so difficult to keep paint from peeling off of exterior wood decks?

A: The culprit here is moisture. Usually, only the top and ends of the boards used on a deck are painted. This leaves the sides and bottom uncoated and able to absorb moisture from rainfall and the soil under the deck. The moisture, drawn to the surface by the heat of the sun, destroys the adhesive bond between the wood and the paint, causing it to blister and peel. The best way to protect a new deck is to apply a deck sealer/toner or semi-transparent stain.

Q: About a year ago, I cleaned and refinished a pressure-treated deck with a clear water repellent. It looked like new when I finished the job, but a few weeks ago my customer called me back because the deck had turned gray again. What went wrong?

A: You probably didn't provide the wood with any protection from the damaging effects of the sun's ultraviolet (UV) rays. Clear water repellents do a great job of protecting wood from damage caused by water, but they usually don't provide any UV protection. Wood that is not protected from UV rays can turn a silver gray color in as little as six months. After you use a deck cleaner to restore the wood to a "like new" look, apply a finish with UV protection. If you want to change the color of the deck, use a semi-transparent stain or a toner. For a clear, natural wood look, try one of the new clear wood finishes that offers UV protection. Many are water reducible for easy clean-up.

Q: What causes frosting? How can it be avoided? What is the proper way to remedy it?

A: Frosting is a phenomenon caused when latex paint is applied in or is subjected to conditions that are too cold and/or too damp during the initial curing process. The lower temperatures and/or dampness do not allow the paint to coalesce, or form a proper film, which then exposes ingredients in the paint film to the elements. The ingredients that cause frosting are water-soluble sodium and calcium compounds. These are added to the paint to improve surface wetting, flow and leveling, and tint acceptance. When the paint film does not coalesce properly, these materials can rise to the surface, where they are exposed to moisture, usually combined with cool temperatures. When the moisture evaporates, a white "frosty" deposit is left on the surface. Frosting can usually be removed by flooding the surface with warm water. High-pressure washing is not necessary; just a lot of water to dissolve the material and flush it off the surface. To prevent frosting, always follow the manufacturers' application recommendations, but especially during the spring and fall when temperatures can drop drastically within the first 24-48 hours of applying paint.

Q: How do you determine the difference between wax bleed and mildew on hardboard siding?

A: Try to clean the area with a mixture of three parts water and one part household bleach. If it comes clean, it's probably mildew. If you spray the area with a spray bottle filled with water (like an old window cleaner bottle) and the water beads up and slides off, the problem could be wax bleed. To further complicate the issue, many areas affected by wax bleed will easily mildew. Because of the sticky wax on the surface, mildew attaches to it very easily.

Q: Some of the houses I repaint look like they have white crystals growing on the exterior siding. What are they and how do I get rid of them?

A: Frosting is a phenomenon caused when latex paint is applied in or is subjected to conditions that are too cold and/or too damp during the initial curing process. The lower temperatures and/or dampness do not allow the paint to coalesce, or form a proper film, which then exposes ingredients in the paint film to the elements. The ingredients that cause frosting are water-soluble sodium and calcium compounds. These are added to the paint to improve surface wetting, flow and leveling, and tint acceptance. When the paint film does not coalesce properly, these materials can rise to the surface, where they are exposed to moisture, usually combined with cool temperatures. When the moisture evaporates, a white "frosty" deposit is left on the surface. Frosting can usually be removed by flooding the surface with warm water. High-pressure washing is not necessary; just a lot of water to dissolve the material and flush it off the surface. To prevent frosting, always follow the manufacturers' application recommendations, but especially during the spring and fall when temperatures can drop drastically within the first 24-48 hours of applying paint. When painting during these times of the year, when the temperature may drop to between 35°F and 50°F, you should use Sherwin-Williams Duration®, Super Paint or A-100 exterior coatings.

Q: I was disappointed to find that the paint I applied over the caulk around windows of a house cracked. What didn't I do right?

A: When paint is applied over a partially dried bead of caulk, the paint forms a film first. As the caulk continues to dry, it separates from the underside of the paint film, resulting in cracks. To prevent this surface defect, allow sufficient time for the caulk to dry prior to painting. Conditions that affect the drying time of caulks are high humidity, wide joints in excess of 1/2 inch in width or depth, and low temperatures (below 40° F).

Q: I occasionally have problems with exterior doors being difficult to open after they've been painted. What causes this and how do I prevent it?

A: Latex paints contain chemicals called plasticizers that allow proper film formation and keep the coating flexible. Many vinyl and plastic weather-stripping materials also contain plasticizers to give them flexibility. When two surfaces containing plasticizers come in contact with each other, they can have the tendency to stick. This condition, known as blocking, will generally occur during the early curing time of the coating, but it can continue for some time. Blocking can also occur on double-hung windows and garage doors. The easiest way to prevent blocking is to use a non-blocking acrylic, or alkyd base paint in areas where it may occur.

Q: Last fall, I painted a house with a glossy oil-based exterior paint. The job looked fine when I finished around 5 p.m.; but when I returned the next morning, some areas were glossy, some flat. What happened?

A: Since you finished painting late in the day, during a season when the temperature usually drops dramatically as soon as the sun goes down, I suspect that moisture was the culprit. In the spring and fall, condensation (dew) forms on surfaces that have been warmed by the sun during the day, then cooled quickly when the air temperature drops after sunset. Using a glossy oil-based paint, which typically takes longer to dry, can compound the problem. The slower drying time allows moisture to get into the paint film before it's fully cured. The result is an uneven, mottled appearance. The problem can usually be fixed by allowing the paint to dry for a couple of days, then applying another light coat of the same paint. Allow this coat to dry for several hours before the sun sets and the temperature drops to prevent a reoccurrence of the problem.

Show More