THE FUNCTION OF PAINTS AND STAINS - PART II
This is part 2 of a 2 part series of articles on paints and stains.
Finally, Interior Paints Coatings for Each Job
Do you ever wonder about the difference between interior and exterior paints? I once used exterior paint on an inside ceiling, reasoning that it could last longer. It could endure longer, but as I found out when I needed to touch up the ceiling only two years later, exterior paints will discolor on an inside surface. Exterior paints contain special additives made to withstand the outside. Interior paints have additives that help the paint dry to a durable, uniform finish.
A lot of the advances in painting technology have been with latex. Actually, latex has overtaken oil-based paint in several areas: durability and elasticity, as well as ease of application, clean-up, and disposal. Latexes have fewer VOCs than oil-based paints. Some, including the Pristine line made by Benjamin Moore, are made with no VOCs in any way. Today's latexes are created with higher quality pigments and binders that give them more body, so each goes on thicker.
Latexes enjoy quite a lttle bit of recognition for interior applications, specifically for walls and ceilings. Alkyds remain the professionals' choice for trimming work because oil based paints are better to paint on detailed surfaces like molding and trim. However, that traditional approach is gradually changing as better latexes, including Pratt & Lambert's Accolade Interior Acrylic Semi Gloss, come on the market.
Exactly What You Are Looking For - Exterior Paint Coatings
Moisture is an important consideration for exterior paint selection. Every day a family of four will create several gallons of vaporized water inside a house.
Coupled with naturally occurring humidity, this can mean a a large amount of moisture moving through the wall space and siding. Dampness is highest in the baths and kitchen. If these rooms aren't sufficiently ventilated, water will migrate through the surfaces. Vapor barriers help contain wetness, but vapor always seeks to leave. The structure of a house, the type of vapor barrier they have, ventilation, and moisture all make selecting the right paint critical.
In wetter climates you need 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 pass through, unlike alkyd paints, which form a waterproof seal. Alkyds also don't flex with areas that expand and contract, as wood does, especially in colder climates. Latex paints have significantly more elasticity, allowing better adhesion.
I favor using latex on all exterior surface areas, including wood siding, stucco, and masonry. Latexes avoid fading much better than most oil-based paints, and they'll cover either oil-based or latex primer (most oils have to go over an alkyd primer).
Latexes do a great job of covering concrete. Despite its hardness, concrete is very porous, and oil-based paints don't always stick well. For greatest durability, I would 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 has to be cleaned with a thinner.
Latex only requires water. Thinners add one more expense, are hard to dispose of, and usually end up spattered on my skin or clothes, regardless of how careful I am.
Solution For Staining Inside
You could spend a life learning about stains and sealers, but there is nothing mysterious about them. The bottom line in determining which stain to work with is to become acquainted with the products available. Read the label, along with any product information you can get, and talk to the personnel at a professional paint shop.
Outside stains come in oil based, varnish, polyurethane, and water-borne solvents. Stains have less colorant than paint and much more solvents, providing them with better wood penetration. Waterproofing is a priority with exterior stains. Most come with built-in sealants to increase strength and help preserve 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 actually used along with a sealer such as urethane or varnish.
Some high quality interior stains have dyes to penetrate and pigments to bring out the richness of the grain. Others contain only pigments, that are simpler to apply, combine, 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 want in one overcoat (be sure to use a conditioner on porous wood, such as pine and birch wood, to avoid splotching). Dyed stains are almost impossible to touch up. Every coating eventually will require touching up, so make certain to consider ease of maintenance in your use 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 wish to avoid the watery nature of stains, try a gel stain, which has had most of the water solvent removed. Gels are easy to use. They spread on, dry fast, and cover evenly. Since they're colored with pigment, gel stains don't penetrate that well. They're a great choice for porous woods that are troublesome to coat evenly without a toner. Gel stains do a excellent job of showing off the grain on embossed metal or composite surfaces. I don't recommend working with them for hardwoods, which require a good dye stain to emphasize the depth and beauty of the grain.
No-Fuss Painting Using Sanding Sealers
Sanding sealers are interior primers that both penetrate and seal wood. You should 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 inhibits them from soaking in to the wood pores. Sanding sealer can provide a better bond for clear coats.
Shellacs are often put into sanding sealers to fortify the resin and offer a quick drying agent. In addition they add an amber tone, so if you're by using a sanding sealer with shellac, make sure it will not influence the stain. Shellacs tend to yellow aver time and contain toluene, which has a very 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 called Rez 77-1. This specific primer/sealer is good for both interiors and exteriors. Pratt & Lambert's Latex Sanding Sealer has very low VOCs, but is only for interior wood and must not be used under a water borne polyurethane.
Oil-based sanding sealers also can be used to seal exterior wood, especially decking, which is continually exposed to sun and water. For color consistency in areas like decks, it's best to completely coat, or back prime, the wood before it goes up, using the same sealer or stain. Olympic Water Guard, Messmer's UV Plus, Behr's, & most top quality deck stains are great water repellent sealers that can also be used for priming exterior wood.
Amazing Wood and Stain Sealers for Interior Wood
Sealers, including varnishes, lacquers, urethanes, and shellacs, are added to the stain itself, applied as a top coat over a stain, or used as a clear coating on unstained wood trim. They can be used for any type of trim, including windows, doorways, and the casing around them. Although you can purchase stain/sealer combinations, they tend to yellow, are difficult to maintain, and don't endure as long as separately applied stain and sealers.
Varnishes contain natural 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 maintain 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 prefer to work with Hope's Tung Oil varnish for a wipe-on maintenance coat. Lacquer is a fast dry sealer that more often than not needs to be sprayed, since it becomes tacky almost immediately.
Polyurethanes do almost anything shellac can do, but they're much easier to maintain. While shellacs act like paint, polyurethanes act more like a clear coating 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 that they don't really require sanding sealers.
The smells associated numerous paints and stains can become more than just offensive, they can be toxic. Solvent based varnishes, lacquers, and shellacs provide a very hard covering but contain very high VOC levels. Water borne sealers, like the stains, match the performance of many solvent based sealers, with fewer VOCs. The VOC content of water based 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 tend to raise the grain. They will also set up or "flash off" quickly at temperature ranges greater than 60°F. The best working temperature for nearly all water based acrylic latex polyurethanes is between 50°F and 60°F, which lets them flash a bit more slowly. In cases like this, flashing-off simply means that the solvent evaporates and leaves the resins to finish the drying out process. A contractor I knew once used water borne 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 based polyurethane, as do Pittsburgh, Pratt & Lambert, Benjamin Moore, and others.
Stains and Sealers for Exterior Applications
Because of their better penetration and sealing power, most exterior stains sold today are oil-based. However, oil-based solid stains peel as they get older, making them more difficult to maintain. A solid stain is similar to paint: It coats more than it penetrates. A latex solid stain peels less and is easier to maintain as it ages. However, I prefer oil-based products for semi-transparent stains. Added oil solvents let them penetrate deeper. A number 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 will often have more solids than a typical exterior stain, which make them more durable. I recommend buying a high-end stain that is semi-transparent or what's called a trans-oxide. Until just lately, the significant problem with exterior stains was their low UV resistance, but newer trans-oxides have finely ground metal mixed in for higher protection. A higher end deck stain won't need a different sealer coating, although you can add one (such as Olympic Water Guard) if you think extra protection is needed to fight moisture content and sun exposure. Better deck stains retail for about $35 a gallon and cover 300 to 400 sq. ft.
Stay away from deck stains which contain silicone. Despite their attractive price, they aren't a good deal. Advertisements for silicone stains and deck sealers often show beaded up water on the deck, and many people are fooled into thinking that this is actually the indication of a successful coating. However, silicon deteriorates quickly, usually in a matter of months, producing a discolored, waxy coat that is a pain to eliminate. The deteriorated silicone also ceases repelling water.
"High build" coatings such as Sikkens and Messmers work remarkably well on outside siding, nevertheless they are too soft to be utilized on your deck. Removing these coatings requires gallons of wood cleaner and way too much work.
Water based outside stains, such as Sherwin Williams Woodscapes, combine the benefits of oil-based and latex coatings. They run and drip significantly 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 great choice for most applications. But bear in mind that cleaning up water based stains can take work. You will find a couple of oil components in the solvent which have to be cleaned. First use soap and water, then alcohol. Ask your supplier for specific cleaning guidelines for water based stains, and read the label.
When In Doubt, Ask Questions
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, proficient salesperson can clear up any questions you might have. Look for a paint store with staff having at least a decade of experience in the business. Ask them what has worked best for your unique application and ask to read a spec sheet on the product in question.
The answers you get will depend on whom you ask. A paint store will attempt to sell you one their own products, after all, that's why they're in business. Painting contractors may not be impartial, either. They have to sell their competence. I get tons of telephone calls from people desiring aid with their painting problems. Most painters, including myself, don't mind giving an hour of time, but if you need in depth answers, consider hiring a contractor for a professional examination. Rates vary, but I charge about $60 for a written and oral examination, depending on the driving time involved. A paid examination will tell you 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
