THE FUNCTION OF PAINTS AND STAINS - PART TWO
This is part 2 of a 2 part series of articles on paints and stains.
Take The Headache Out of Finding Interior Paints Coatings for Every Job
Do you ever wonder about the difference between interior and exterior paints? I once used exterior paint on an indoor ceiling, reasoning that it could last longer. It may last longer, but as I then found out when I was required to touch up the ceiling only 2 years later, exterior paints will discolor on an interior surface. Exterior paints contain special additives designed to withstand the outside. Interior paints have additives that help the paint dry to a durable, uniform finish.
Most of the advances in painting technology have been with latex. Actually, latex has overtaken oil-based paint in a number of areas: toughness and elasticity, as well as ease of use, clean-up, and disposal. Latexes have fewer VOCs than oil-based paints. Some, like the Pristine brand created by Benjamin Moore, are made without VOCs whatsoever. Today's latexes are created with top quality pigments and binders that provide them more body, so they go on thicker.
Latexes enjoy quite a lttle bit of acceptance for interior applications, especially for walls and ceilings. Alkyds stay the professionals' choice for trimming work because oil based paints are simpler to paint on detailed surfaces like molding and trim. However, that traditional approach is slowly changing as better latexes, including Pratt & Lambert's Accolade Interior Acrylic Semi Gloss, are introduced to the market.
Exterior Paints Coatings for Each Job
Moisture is an important consideration for exterior paint selection. Every day a family of four will generate several gallons of vaporized water in the house.
Combined with naturally occurring humidity, this can mean a lot of moisture moving through the walls and siding. Wetness is highest in the baths and kitchen. If these rooms aren't sufficiently ventilated, water will migrate through the walls. Vapor barriers help contain wetness, but vapor always seeks to escape. The structure of a home, the kind of vapor barrier it has, ventilation, and humidity all make choosing the right paint critical.
In wetter climates you require a paint that will let moisture go through the wood, so water doesn't get trapped under the paint and cause blistering and peeling. Latexes are porous and let water go through, unlike alkyd paints, which form a waterproof seal. Alkyds also don't flex with areas that expand and shrink, as wood does, especially in colder climates. Latex paints have significantly more elasticity, allowing better adhesion.
I favor using latex on all exterior areas, including wood siding, stucco, and cement. Latexes resist fading much better than most oil-based paints, and they will cover either oil-based or latex primer (most oils have to go on top of an alkyd primer).
Latexes do a great job of covering cement. Despite its hardness, concrete is very porous, and oil-based paints don't always adhere well. For ideal durability, I recommend latex enamel.
In general, if I know of a latex product that provides superior performance, I will choose it over an oil-based product that needs to be cleaned with a thinner.
Latex only needs water. Thinners add yet another cost, are hard to dispose of, and usually end up spattered on my skin or clothes, regardless of how careful I am.
Take The Headache Out of Using Stains
You can spend a life studying stains and sealers, but there is nothing mysterious about them. The bottom line in figuring out which stain to use is to become acquainted with the products available. Scan the label, along with any product information you can get, and talk to the staff at a professional paint shop.
Outside stains come in oil based, varnish, polyurethane, and water-borne solvents. Stains have less colorant than paint and more solvents, giving them better wood penetration. Waterproofing is important with exterior stains. Most come with built-in sealants to increase sturdiness and help maintain the wood. The color in stains can be pigments, dyes, or both. A semi-transparent stain has more dye for grain penetration. A solid stain has more pigment for surface covering. Pigment is a finely ground coloring that doesn't penetrate the grain as deeply as a dye. That is why a pigmented stain is usually used along with a sealer such as urethane or varnish.
Some high quality interior stains have dyes to penetrate and pigments to draw out the richness of the grain. Others contain only pigments, that are easier to apply, mix, and touch up. Pigmented stains are lighter in color and bring out more of the wood grain. If you are looking for darker results, a dyed stain will provide what you would like in one layer (make sure to use a conditioner on porous wood, such as pine and birch wood, to avoid splotching). Dyed stains are extremely difficult to touch up. Every coating eventually will need touching up, so make certain to consider ease of maintenance in your choice of stains. You'll get the best results by using better stains such as Minwax, Pratt & Lambert's Tonetic, Pittsburgh's Rez, or Wood-Kote.
If you want to steer clear of the watery nature of stains, try a gel stain, which has had almost all of the liquid solvent removed. Gels are easy to use. They spread on, dry out fast, and cover evenly. Since they're colored with pigment, gel stains don't penetrate that well. They're a good choice for porous woods that are difficult to cover evenly without a toner. Gel stains do a great job of showing off the grain on embossed metal or composite surfaces. I don't recommend working with them for hardwoods, which need a good dye stain to emphasize the depth and beauty of the grain.
Learn How to Use Sanding Sealers
Sanding sealers are interior primers that both penetrate and seal wood. You can use them under clear coats or on top of stains as sealers. Sanding sealers are different from a sealer like polyurethane, which is not made to prime. They're similar to varnish, but diluted with solvents to permit better penetration for priming. The hardness of varnishes and lacquers helps prevent them from soaking in to the wood pores. Sanding sealer can provide a better adherence for clear coats.
Shellacs tend to be added to sanding sealers to strengthen the resin and provide a quick drying agent. They also add an amber tone, so if you are by using a sanding sealer with shellac, make sure it won't have an impact on the stain. Shellacs have a tendency to yellow aver time and contain toluene, that has a high VOC content. Shellacs are gradually supplying ways to new sanding sealer formulas with lower VOCs and better performance.
Alkyd resin sanding sealers also have high VOCs, although significantly less than their shellac based cousins. Pittsburgh Paints makes a slow drying alkyd resin sanding sealer without shellac named Rez 77-1. This particular primer/sealer is wonderful for both interiors and exteriors. Pratt & Lambert's Latex Sanding Sealer has very low VOCs, but is only for interior wood and shouldn't be used under a water based polyurethane.
Oil-based sanding sealers also can be utilized to seal outside wood, especially decking, which is continually exposed to sun and water. For color regularity in areas like decks, it's best to completely coat, or back prime, the wood before it is in place, using the same sealer or stain. Olympic Water Guard, Messmer's UV Plus, Behr's, & most top quality deck stains are excellent water repellent sealers that also can be used for priming exterior wood.
Wood and Stain Sealers for Interior Wood – Safely
Sealers, including varnishes, lacquers, urethanes, and shellacs, are put into the stain itself, applied as a top coat on top of a stain, or used as a clear coat on unstained wood trim. They could be used for any type of wood trim, including windows, entrance doors, and the casing around them. Although you can buy stain/sealer combinations, they tend to yellow, are difficult to keep up, and don't endure as long as separately applied stain and sealers.
Varnishes contain oils such as Tung oil, an extremely hard, durable sealant that may be brushed on and dries slowly. Varnishes are easy to completely clean and keep maintaining with soap and water accompanied by a wiped on varnish, which usually keeps a wood surface looking great for years. Make certain there's no wax in your cleaner, because wax clogs wood pores. I favor making use of Hope's Tung Oil varnish for a wipe-on maintenance overcoat. Lacquer is a fast drying sealer that almost always must be sprayed, since it becomes tacky almost immediately.
Polyurethanes do almost everything shellac does, but they're much easier to maintain. While shellacs act like paint, polyurethanes act more like a clear coat that permeates the wood instead of sitting on top of it. Polyurethanes brush on and dry quickly, with little scent and VOCs. They have more or less replaced shellacs as a clear sealer. Another reason urethanes have grown to be such popular sealers is the fact they don't require sanding sealers.
The smells associated numerous paints and stains can be more than just offensive, they can be toxic. Solvent based varnishes, lacquers, and shellacs give a ultra hard coating but contain very high VOC levels. Water based sealers, like the stains, match the performance of many solvent based sealers, with fewer VOCs. The VOC content of water borne sealers such as Sherwin Williams Kern Aqua Lacquer average about 250 grams per liter, or 2 pounds per gallon, half the usual VOCs of oil-based lacquers. The ethers in water based sealers aren't combustible, another advantage, but they still have enough VOCs to warrant a respirator.
Although they resist yellowing, water borne sealers such as acrylic latex polyurethanes do have a tendency to raise the grain. They will also set up or "flash off" quickly at conditions higher than 60°F. The very best working temperature for nearly all water borne acrylic latex polyurethanes is between 50°F and 60°F, which lets them flash a bit more slowly. In this case, flashing-off simply means that the solvent evaporates and leaves the resins to complete the drying process. A contractor I know once used water based latex polyurethane sealer that flashed off so fast he could only apply it between 5 A.M. and 9 A.M. Anything later than that was too warm.
Minwax makes very good water borne polyurethane, as do Pittsburgh, Pratt & Lambert, Benjamin Moore, as well as others.
Amazing Stains and Sealers for Exteriors
Because of their better penetration and sealing ability, most exterior stains sold today are oil-based. However, oil-based solid stains peel off as they get older, making them more difficult to maintain. A solid stain is like paint: It coats more than it penetrates. A latex solid stain peels less which is easier to maintain as it ages. However, I favor oil-based products for semi-transparent stains. Added oil solvents let them penetrate deeper. Some of the better stains on the marketplace include Pittsburgh Solid Color Latex Stain, Messmer's U.V Plus, Moorwood Solid Color Exterior Stain, Sherwin Williams Woodscape stains, Pittsburgh Semi-transparent Exterior Stain, Rez Deck Stain by Pittsburgh, and the Sikkens Cetol system.
Deck stains usually have more solids than a typical exterior stain, which make them stronger. I recommend buying a high-end stain that is semi-transparent or what is called a trans-oxide. Until just lately, the major problem with outside stains was their low UV resistance, but newer trans-oxides have finely ground metal mixed in for increased protection. A high end deck stain won't need a separate sealer coating, although you can include one (such as Olympic Water Guard) if you think extra protection is required to battle moisture content and sun exposure. Better deck stains retail for approximately $35 a gallon and cover 300 to 400 sq. ft.
Avoid using deck stains that contain silicone. Despite their low price, they aren't a good deal. Advertisements for silicon stains and deck sealers often show beaded up water on a deck, and many people are fooled into thinking that this is the indication of a successful coating. However, silicone breaks down quickly, usually in just a matter of months, producing a discolored, waxy coat that is clearly a pain to eliminate. The broken down silicone also quits repelling water.
"High build" coatings such as Sikkens and Messmers work remarkably well on outside siding, but they are too soft to be used on your deck. Stripping these coatings can take gallons of wood cleaner and a significant amount of work.
Water borne exterior stains, such as Sherwin Williams Woodscapes, incorporate the features of oil-based and latex coatings. They run and drip less than oil based stain, and dry faster, enabling two coatings the same day. Water borne stains possess the resilience and overall flexibility of the latex stain, giving them stamina. They're a good choice for most applications. But bear in mind that cleaning up water borne stains calls for work. You will discover a couple of oil components in the solvent that have to be cleaned. First use soap and water, then alcohol. Ask your dealer for specific cleaning directions for water borne stains, and scan the label.
When In Doubt, Ask Your Painting Professional
If you still have questions about which paint or stain to make use of, don't hesitate to ask people in the know. A skilled, educated salesperson can answer any questions you might have. Choose a paint store with personnel having at least 10 years of experience in the business. Ask them what has worked best for your particular application and ask to see a spec sheet on the merchandise in question.
The answers you get will depend on whom you ask. A paint store will attempt to market you one of their products, in the end, that is why they're in business. Painting contractors may not be impartial, either. They have to sell their knowledge. I get plenty of calls from people looking for help with their painting problems. Most painters, including myself, don't object to giving an hour of time, but if you need comprehensive answers, consider hiring a contractor for a professional analysis. Rates vary, but I usually charge about $60 for a written and oral examination, depending on the driving time involved. A paid evaluation will let you know whether you should paint, stain, or re-side, as well as which coating might be best for finishing your project. Each painting job has unique conditions that warrant specific answers.
Sound Quality Painting
824 90th Dr SE suite B
Lake Stevens WA 98258
(425) 512-7400
