Recent Questions

Q: Should I caulk the lap joints on my siding? I have heard that uncaulked lap seams allow moisture to escape.

A: It is not a good idea to caulk the lap on your siding. To do so could trap moisture from inside the home behind the siding, causing it to come out through the paint, resulting in peeling.

Q: I occasionally paint buildings where non-galvanized iron nails were used in siding and have rusted, causing a bleeding on the old paint surface. Will an acrylic latex cover these stains and prevent further bleed-through, or must something be done to these nailheads before applying the acrylic latex topcoat?

A: Stains caused by rusted nails will bleed through the topcoat of even the most durable paints unless a stain-resistant solvent-based or acrylic latex primer has been applied first. If you are painting new exterior construction where non-galvanized nails have been used, it's advisable to spot-prime the nailheads and any knots in the wood prior to applying the topcoat.

Q: How do I find out if the paint on a house exterior is latex or oil? Is there a quick test?

A: If the old paint is peeling, take a good size piece of the peeling paint and hold the edges of it between your thumb and index finger. Exert pressure on both sides of the chip. If it is very flexible and bends easily, it is probably latex. If it is hard, brittle and breaks instead of bending, it is most likely oil-based paint. Another way to test the paint is to wet a rag with denatured alcohol and rub the surface of the paint. If the paint softens or rubs off, it is most likely latex. An alcohol test usually will not affect an oil-base paint.

Q: Why do I need to use a primer instead of just using two coats of the finish paint?

A: A primer is beneficial because it helps provide a uniform surface that promotes good adhesion of the topcoat. A primer can also serve a special purpose by sealing a porous surface, blocking out stains, preventing rust formation on iron and steel, and preventing tannin bleed on wood. Most finish paints are designed to provide a decorative or protective finish for a substrate. In most situations, they do not provide the features of a primer, so it is always important to follow the manufacturer's recommended coating system.

Q: What causes fisheyes

A: Fisheyes are caused by some type of surface contamination that was not removed in preparation for painting. This contamination can be from body oils, silicone from furniture polish, or any greasy or oil substance. The slippery deposit on the surface does not allow the paint to adhere, causing it to shrink away from the contamination and form a dimple-like void in the paint film.

Q: What types of cleaners can I use to remove mildew?

A: Try using a solution of one quart household bleach in three quarts of water. Apply the solution to the area with mildew and then rinse off with water. Never add detergents or ammonia to the bleach/water solution. Always protect your skin and eyes against splashes.

Q: What is the best way to clean a new galvanized surface before painting?

A: If it is not practical to allow the surface to weather for six months before painting, it must be cleaned with a solvent to remove any surface contaminants and oils applied by the manufacturer to prevent oxidation of the zinc in the galvanized coating. This is best accomplished by using a water-soluble degreasing cleaner applied with a clean cloth or sponge. Change sponge or cloth and cleaning solution frequently so the dirt and oil are removed from the surface, not just spread to other areas. Rinse the surface thoroughly and allow to dry before painting.

Q: How long should I wait to apply paint over new stucco?

A: Until recently, you had to wait one to two months for the stucco to cure properly. However, new-generation masonry primers speed up the process considerably. For instance, Loxon Exterior Masonry Primer from Sherwin-Williams can be applied as soon as the stucco is hard, dry and at a pH level of less than 13. After the primer dries, you can follow with latex house paint immediately.

Q: Can you paint over existing glass particle type stucco and if so, how?

A: Handle it the same as you would a regular stucco finish. Loxon Exterior Masonry Primer can be applied as soon as the stucco is hard, dry and at a pH level of less than 13. After the primer dries, you can follow with Duration® or Super Paint. The small glass particles should be imbedded into the stucco enough that they shouldn't bother the adhesion of the new paint.

Q: Is it necessary to prime aluminum or vinyl siding before painting?

A: No, as long as the siding has had a chance to weather a year before painting. You do need to clean the surfaces first with an Extra Strength Cleaner Degreaser. You want to be sure the surfaces are free of chalk and residue.

Q: How should vinyl siding be prepared prior to painting?

A: Power wash the vinyl siding or use warm soapy water to remove dirt and chalk. Wire brushing or sanding can mar the surface and cause permanent imperfections.

Q: How would you handle aluminum siding that has been painted a few times and now has a chalky quality that rubs off when touched?

A: Any surface that has a chalky feel should be cleaned to remove the chalk before painting. The easiest and most effective way to do this is by pressure washing and using a chemical injection system attached for the detergent. Be sure to allow the siding to dry a day or so, to allow the water that is driven up behind the siding to work its way out before painting.

Q: Is acrylic latex paint a good product for rough-sawn exterior grade plywood siding? Should the plywood siding be treated with a preservative before applying the primer and then topcoat?

A: Quality acrylic latex paint is an excellent choice for painting rough-sawn exterior plywood siding. Preservative treatment of the wood before painting is not necessary if proper construction practices are followed when installing the siding. There should be no contact of the bottom edge of the siding with soil or other surfaces where water can puddle.

Q: How long do I have to wait before staining or painting a new pressure-treated deck?

A: In the past, the rule of thumb was to wait until the green color faded away. Recent studies have shown that waiting the six to 12 months necessary for this to happen allows the wood to deteriorate too much. To adequately protect treated wood from the harmful effects of rain, snow, mildew and the sun's ultraviolet rays, the wood should be allowed to thoroughly dry first. Then if the wood will accept a finish, coat it with one of the Sherwin-Williams SuperDeck® systems.

Q: I have an old deck that my customer would like painted. What is the process for such a project? Will it extend the life of the deck?

A: Painting a wood deck can be the start of an ongoing, frequent painting project. You will be much better off in the long run to take the time now to remove any existing finish, clean the wood, and finish the deck with a deck sealer or stain.

When you apply paint to a deck, you put a continuous film of paint on the surface. Also, you are usually only able to paint the top and ends of the boards, leaving the sides and underside unprotected and able to absorb moisture. The moisture in the wood is then drawn to the surface by the heat of the sun and gets trapped under the continuous film of paint. The paint then blisters and peels, and you start the cycle over again.

A deck sealer or stain does not form a film like paint, but still protects the wood from the elements and allows moisture to pass through it, lessening the likelihood of blistering and peeling. Most of the sealers and stains are clear or semi-transparent, so the wood has to be in pretty good shape to be able to use them. There are some solid color stains designed specifically to handle foot traffic on a deck that can be applied on an old deck after it is prepared according to the manufacturer's label instructions.

Q: I have a house with masonite siding that hasn't been painted in several years. In places the paint is in really bad shape. What is the best way to remove the old paint? Do you recommend a quick-drying primer/sealer for priming damaged masonite siding?

A: The best way to remove the old paint is by scraping and sanding to bare wood. Be careful not to be too aggressive or you'll damage the siding. If the siding has deteriorated, or is "swelling" due to water absorption, it should be replaced. I recommend an exterior grade alkyd primer followed by two coats of acrylic latex house paint. The alkyd primer is best because it seals better on the lower edge of the siding, which helps prevent edge swell, a common problem on hardboard siding.

Q: Does preprimed hardboard siding have to be primed after it is installed on a house?

A: It is always a good idea to check the siding manufacturers' recommendations before painting, but in most situations it won't hurt to apply a coat of exterior alkyd primer before applying two coats of an acrylic latex topcoat. A coat of primer will promote better adhesion of the topcoat and assure that the hardboard, particularly the bottom edge, is adequately sealed from the elements.

Q: What determines if a joint should be recaulked? Should old caulk always be removed?

A: If the old caulk is cracking or pulling away from the surface, dig it out and replace it. Prime the bare wood then re-caulk. Any butt joint in siding or other joints between two pieces of wood should be caulked. You DO NOT want to caulk the lap joints of siding since they allow moisture to get out from behind the wood.

Q: How do I determine when a concrete floor is ready to paint?

A: New concrete should cure for at least 30 days. Check for moisture by taping a 2'x2' piece of 4-mil plastic to the floor with duct tape. If no darkening of the concrete or condensation is evident after 24 hours, the floor is dry enough to paint. The floor should be thoroughly cleaned and acid etched prior to application.

Q: Can acrylic latex house paint be applied over gloss alkyd paint? Is special prep work necessary to ensure good adhesion?

A: Yes, to both questions. But, to ensure good adhesion, glossy surfaces must first be washed clean and then sanded to allow the paint to "grip" the surface. Gloss alkyd paints that are exposed to harsh weather conditions have a tendency to "chalk" - that is, the old paint film develops a faded, powdery substance on the surface. So it's best to wash off any excessive chalk prior to applying an acrylic topcoat. When painting bare surfaces, use an appropriate primer before applying the topcoat. This will ensure the best adhesion and long-term durability.

Q: Many of the specifications I read call for solvent cleaning as the surface preparation. What's the best solvent to use?

A: The most popular specification for solvent cleaning is SSPC-SP 1, from the Steel Structures Painting Council. It describes solvent cleaning as "A method for removing all visible oil, grease, soil, drawing and cutting compounds, and other soluble contaminants from steel surfaces." Although they may be used in some situations, "solvent" does not necessarily refer to paint solvents such as mineral spirits, xylene, lacquer thinner, etc. Many contractors prefer to steam clean or use a water-based emulsion or alkaline cleaners to remove the contamination. For environmental and safety reasons, it's best to use the mildest "solvent" that will get the job done.

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