Recent Questions

Q: Which spray primers are acceptable for bare aluminum? I have heard that zinc primers are fine for nonferrous metals, but the spray cans never say anything about usage on aluminum. Can epoxy or acrylic be used without a primer?

A: Alkyd paints are "usually" not recommended for application direct to aluminum because of possible saponification (a reaction between the fatty acids in the alkyd and the aluminum salts when moisture is present). Since most aerosol spray enamels are alkyd based, you have the potential for problems when you apply them to aluminum. An epoxy ester or acrylic aerosol spray would be a better choice for painting small pieces of clean aluminum.

Q: What is the best paint to use on handrails, material handling equipment and other surfaces exposed to heavy wear-and-tear?

A: A two-component polyurethane coating will produce a hard, durable finish as well as provide effective color and gloss retention in areas that must withstand a lot of physical abuse. Over properly prepared and primed substrates, two-component polyurethanes provide a tough, long-lasting finish.

Q: Can paint that has been frozen still be used?

A: It depends on the coating, you will need to open the container and observe the coating. After gradually bringing frozen paint up to room temperature (70 degrees F), open the can and stir it. If the paint looks like a fresh, never-been-frozen can of the same product, it should be safe to use. When inspecting a thawed can of paint, be especially wary of lumps, thickening or solid pieces that can't be broken. If any are present, the paint should not be used. In general, it's best to prevent such problems by protecting paint - especially water-based latex paints - from freezing temperatures.

Q: My customer wants a pickle wash finish on her cabinets. How do I create it?

A: For a conventional system, use Wood Classics Stain Pickled White and one of the Wood Classics topcoats. A non-yellowing system would be a first coat of 10 parts White Vinyl Sealer (P63W2) mixed with 2 parts Vinyl Sealer (T67F3). Topcoat with one or two coats of Sher-Wood CAB Acrylic Lacquer. This system is designed for spray application. All of these products are available at your Sherwin-Williams Store.

Q: I paint for customers who need the toughness of an epoxy, but they find the odor too offensive. What should I use?

A: Your best option is to upgrade from a traditional latex or alkyd system to a water-based catalyzed epoxy. It will offer many of the same characteristics as a solvent-based epoxy, such as a abrasion resistance, hardness, chemical resistance and scrubability, without the strong and lingering odor. This is why water-based epoxies are often used in schools, nursing homes, hospitals, kitchens and food plants. Water-based epoxies are also highly compatible with other previous coatings, which eliminates the lifting problem you could encounter with a solvent-based epoxy.

Q: What basic ingredient gives paint its hiding power?

A: Of the three main paint ingredients - pigments, solvents and binders - the pigment provides hiding power and gives paint its color and shading. The solvents carry the paint to the surface, then evaporate, leaving behind a film of paint; the binders are bonding agents that hold the paint together.

Q: The VOC requirements I read about are expressed grams per liter, but I buy paint in gallons. How do I know if I'm in compliance?

A: Simply divide the grams per liter amount by 120 to determine the pounds per gallon figure. For instance, a product that has a VOC of 250 grams per liter would have 2.08 pounds per gallon, because 250/120 = 2.08. To convert from pounds per gallon to grams per liter, multiply the number of pounds by 120.

Q: What is the best paint to use on a garage floor?

A: It depends on what kind of finish you want. A clear heavy-duty, high-performance polyurethane will provide a durable, dust-free clear finish if the concrete has a uniform appearance. If the concrete's finish is not uniform, or if you want a colored finish on the floor, a two-part polyamide epoxy works best. Do not use latex or oil-based floor paint in a garage because they can lift when they come in contact with car or truck tires. For best results, allow the coating to cure at least 10 days before driving a vehicle on it.

Q: How can I upgrade a coating system from an alkyd to a urethane or epoxy without completely removing the old finish?

A: In many cases, the application of a high-solids universal primer or barrier coat will allow the application of a strong solvent-based epoxy or urethane over a previous coating. Using a barrier coat reduces the likelihood of the solvents in the topcoat lifting previous finishes and eliminates the need for costly and time-consuming removal of all existing paint.

Q: What kind of paint works best on galvanized surfaces?

A: After allowing the galvanized surface to weather for six months or chemically cleaning it to remove any oil or remnants of the galvanizing process, you can apply two coats of an acrylic latex paint directly to the metal or a special galvanized metal primer topcoated with an alkyd or latex product. Do not apply an alkyd directly to a galvanized metal surface because the oils will react with the zinc used in the galvanizing process, causing the alkyd to peel.

Q: Is latex paint susceptible to "lapping" when a gloss or color difference appears in double-coated areas? What should be done to avoid this?

A: Lapping occurs when paint dries too quickly, causing noticeable gloss, color and hiding differences where the paint overlapped during application. In the past, this was problem - particularly with latex paints on porous surfaces. However, with advancements in rheology modifiers and thickeners, lapping has become less of a problem, especially with top-quality latex paints that are more likely to contain these ingredients.

Q: What is so special about a zinc-rich primer?

A: Primers rich in zinc provide a tight, moisture-barrier film that protects steel from corrosion by sacrificing itself rather than allowing the steel to rust. Zinc primers also self-heal and resume protection of the steel if the coating is damaged.

Q: I have always recommended alkyd enamels for bathroom walls and ceilings. Now I hear the preferred coating is an eg-shel latex or an acrylic because they let the walls "breathe." Which do you recommend?

A: Alkyds traditionally have a tighter film and seal the surface better. They are, however, more prone to mildew than latex paint. Traditional latex eg-shel and semi-gloss coatings work well in a bathroom as long as there is good ventilation. If the walls are damp because of poor ventilation, you may run into problems with surfactant leaching (brownish stains on the paint) or peeling paint. I suggest you use Duration Home®. It resists most household stains, and because of the tight film it forms, it is stain-resistant, moisture-resistant and mildew-resistant too.

Q: How can I cover and paint over a water-stained but otherwise undamaged ceiling?

A: After you have corrected the cause of the water staining, use a primer sealer designed for stain blocking, such as ProBlock Primer/Sealers. They are available in both alkyd and latex-based versions. While both work to block this type of stain, the alkyd stain blocker will usually seal water stains better because it doesn't contain water that could re-wet the stain. You may still see the stain through the stain blocker, but they are designed to "lock-in" the stain to prevent it from bleeding through into the topcoat.

Q: What makes a better paint? Do more expensive paints contain more durable pigments and resins?

A: Yes they do. You hit on some key items that improve the quality of finish. The resins along with the binders give you the quality of finish. Also, the way the product is produced can impact the quality. Paint goes through a piece of machinery called a ball mill. This grinds everything together. The size of the balls used and length of time it goes through the mill impacts the fineness of the pigment grind, which impacts the quality of the product.

Q: What chemical component of paint is responsible for the sheen level?

A: The resin is responsible for the sheen level (latex & alkyd).

Q: I see the term "Volume Solids" in most specifications. What does it mean, and why is it so important?

A: Paint is made up of four basic elements: solvent, binder, pigment and additives. The material left on a substrate after the solvent evaporates and the coating cures is its solids content. When calculated as a percentage of the total gallon of paint, the solids are referred to as "Volume Solids." A higher percentage of Volume Solids is usually an indication of a better quality paint, because more binder and pigment are left to protect the surface compared to a coating with a lower Volume Solids rating.

Q: Is it true that I won't be able to buy oil-based paints in the future?

A: A lot depends on the VOC limits the federal government sets when it implements a national VOC regulation. Based on the latest information we have, you should be able to use oil-based paints for some time. The oil-based products you'll use in years to come will be different than the ones you use now. They'll contain more solids and less solvent, and may apply and dry differently than current products.

In the meantime, you might want to try the new waterborne products that are being developed. They apply, level, and dry to a hard film like an alkyd; but they're non-yellowing, clean up with soap and water, and cause less odor.

Q: With all the talk about VOC emissions from solvents in paint, I'm confused. If latex paint is water-based, how can it contain VOCs?

A: Traditional latex technology requires the use of co-solvents to get the latex particles to melt together (coalesce). These small amounts of solvents, and some additives, make up the VOC content in normal latex paints. New technology has been developed that allows latex paint films to form without co-solvents. These new products perform similar to traditional latex paints, but have minimal VOC levels and less odor.

Q: Why are certain trim colors, such as red, so tough to cover on the second coat? Would it be best to apply some kind of primer and then an acrylic latex topcoat to cover more easily? What other colors are tough to cover?

A: Difficulty in covering a previously painted surface relates not so much to the color of the earlier paint, but to how dark it is. The recoat hiding problem is compounded when a very light color (most noticeably yellow) is applied over a dark one. Multiple coats of paint are often necessary in these cases. Using a primer as a first coat may help, depending on the hiding of the primer and of the topcoat. Using a poor hiding primer may be no better than using two topcoats. Also, using a gray shade of primer will help more than tinting the primer color close to the existing shade.

Q: How do flat, satin and semi-gloss finishes differ in terms of appearance, durability and washability?

A: Flat finishes hide imperfections in the surface. The higher the sheen the better/smoother the surface has to be if you are concerned about the cosmetic appearance of the wall. With advances in technology you can purchase flat finishes that offer very good washable surfaces (Sherwin-Williams Duration Home) or scrubbable (Sherwin-Williams Harmony), satin and semi gloss finishes are considered more scrubbable than flat finishes.

Q: It seems that darker colored acrylic latex paint has a longer service life than lighter colors. Can this be true?

A: Yes, it's possible. Even if all other factors are equal, this situation can occur if the darker color is based solely on a durable oxide "earth" color, such as red iron oxide, and the lighter color contains a portion of titanium dioxide (a white pigment), which contributes to chalking.

Q: I've got some exterior latex house paint left over from last summer's jobs. Can I mix it together to use for an interior primer or topcoat?

A: No. They will not perform properly inside. Exterior paints are made to be flexible and withstand the weather, but not to take the physical abuse such as abrasion and scrubbing that interior paints are subject to.

Q: What factors are most significant in determining paint quality? We are about to paint a Victorian home and are looking for the highest quality exterior paint. Longevity without shrinking, cracking or loss of luster are our primary concerns.

A: The main factors are the type and amount of resin (the binder that holds the paint together), type and amount of pigment, volume solids and film thickness. A high quality paint like Sherwin-Williams Duration, has enough volume solids for applying one coat at 2.8 mils dry film thickness. This is the longest lasting coating that Sherwin-Williams has to paint the exterior of a home.

Q: If alkyd paint yellows with time and latex holds its color better, why do many people still prefer alkyd for interior trim?

A: Alkyd paints use to be harder and more durable for interior trim work. With recent advances in paint technology, even the most tradition-bound paint customers are choosing the new latex coatings for interior trim work. Sherwin-Williams ProClassic Waterborne interior semi-gloss offers many of the attributes of alkyds; good adhesion, scrubbability, hardness, flow and leveling and without the yellowing or odor of an alkyd.

Q: Oil-based paints seem to become brittle after years of wear. Will acrylic latex paint deteriorate like this?

A: No. The particles of acrylic latex paint fuse together to form a film that remains flexible over the life of the paint. This film has the ability to expand and contract with the surface, which helps give the paint superior durability. Oil-based paint forms its film through constant chemical reaction over the life of the paint. This process causes these paints to gradually become brittle, which can result in paint failures such as cracking and flaking.

Q: I was discouraged to find mildew return after replacing caulk around a tub. I'm about to remove the caulk again. Any suggestions on how to prevent this problem from reoccurring?

A: Once you have removed the caulk, be sure to bleach the area underneath it thoroughly. Use a solution of one part bleach and four parts water. This should kill the mildew. If your problem is severe you may need to go to a stronger solution of bleach and water.

Q: What is your most washable interior wall paint?

A: Sherwin-Williams Duration Home is our most washable interior wall paints. Simply put "Stains don't stand a chance."

Q: Why is it so common that the deep colors (hunter greens, deep burgundies) never touch up, even when using the same paint that was originally used just a few days or weeks later?

A: Deep colors are naturally loaded with pigments that need to stay dispersed in the paint during application. If the paint is not stirred frequently, you could be applying different concentrations of colored pigments at different times during application. Then when you go back to touch up with a freshly stirred bucket of paint, you could be putting more or less pigment onto the wall, causing it to look different. When touching up painted surfaces, it's a good idea to use the original can of paint and reduce it 15 to 25 percent. This will prevent film buildup, which can also cause a difference in appearance. You should apply the touch-up paint with the same type of applicator (brush, roller or spray) you used to apply the original paint. This will prevent texture differences, which make the touch-up areas more visible.

Q: What is the best primer to use when painting interior stained wood? I have to paint over some dark stained trim.

A: Make sure the surface is clean, dry and dull first. Then we suggest using a traditional alkyd wood primer, like ProBlock Alkyd Primer, for better coverage over the darker color. Other stain killers/primer/sealers work great to seal stains, and dry quickly. These primers usually don't have the pigment load needed to cover over a dark color like ProBlock Alkyd Primer.

Q: Can you suggest a heavy-duty paint for painting the floor of an industrial building? The current paint lasted only a few months.

A: We recommend our Heavy-Duty ArmorSeal Floor Coatings. Surface prep is important. For best performance, remove the old coating using a shot blaster. This will remove the old paint and give an excellent profile, which the new finish can adhere to. Apply the base coat of primer, then topcoat, following the manufacturer's label instructions for mixing and application.

Q: When I use satin varnishes, I occasionally end up with some satin areas and some glossy areas. What causes this, and how do I prevent it?

A: Most satin varnishes are actually gloss varnishes with a flattening agent added to reduce the gloss. The flattening agent is usually heavier than the varnish, so it drops to the bottom of the can. You can see this by comparing a can of gloss and satin varnish. The gloss varnish will be clear all the way to the bottom of the can, while the satin will have clear material on top and cloudy material on the bottom. The cloudy material is the flattening agent. Before using satin varnish, stir it thoroughly with a paint paddle to suspend the flattening agent throughout the can. (Do not shake varnish, as air bubbles that cause unsightly blemishes in the finish will form.) Stir the varnish frequently during application to keep the flattening agent suspended. If you don't stir often enough, you'll get some brush loads of varnish with the flattening agent and some without. This is what causes a finish with uneven gloss.

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