THE PURPOSE 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 inside ceiling, reasoning that it would last longer. It may last longer, but as I then found out when I had to touch up the ceiling only two years later, exterior paints will discolor on an inside surface. Exterior paints contain special additives designed to withstand the outside. Interior paints have additives that help the paint dry out to a durable, uniform surface finish.
Most of the advances in painting technology have been with latex. In fact, latex has overtaken oil-based paint in several areas: toughness and elasticity, as well as ease of application, clean-up, and disposal. Latexes have fewer VOCs than oil-based paints. Some, including the Pristine brand made by Benjamin Moore, are made with no VOCs whatsoever. Today's latexes are made with top quality pigments and binders that provide them more body, so each goes on thicker.
Latexes enjoy quite a lttle bit of popularity for interior applications, specifically for walls and ceilings. Alkyds remain the professionals' choice for trim work because oil based paints are simpler to paint on detailed areas like molding and hardwood trim. However, that traditional approach is gradually changing as better latexes, including Pratt & Lambert's Accolade Interior Acrylic Semi Gloss, are introduced to the market.
High Demand Exterior Paint Coatings
Moisture can be an important concern for exterior paint selection. Each day a family of four will create several gallons of vaporized water in the house.
Combined with naturally occurring humidity, this can mean a a large amount of moisture moving through the surfaces and siding. Moisture 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 escape. The structure of a home, the kind of vapor barrier it has, ventilation, and dampness all make choosing the right paint critical.
In wetter climates you need a paint that will let moisture pass 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 floors that expand and shrink, as wood will, especially in colder climates. Latex paints have more elasticity, allowing better adhesion.
I prefer using latex on most exterior areas, including wood siding, stucco, and cement. Latexes avoid fading much better than most oil-based paints, and they will cover either oil-based or latex primer (most oils have to go over an alkyd primer).
Latexes do a great job of covering cement. Despite its hardness, cement 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 will provide superior performance, I'll 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.
How to Stain Interior Surfaces
You are able to spend a life learning about stains and sealers, but there's nothing mysterious about them. The bottom line in determining which stain to use is to familiarize yourself 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.
Exterior 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 important with exterior stains. Most include built-in sealants to increase durability 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's why a pigmented stain is definitely 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 draw 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 the ease of maintenance in your use of stains. You'll receive 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 the majority of the water solvent removed. Gels are simple to use. They spread on, dry out fast, and cover evenly. Because they're colored with pigment, gel stains don't penetrate that well. They're a great choice for porous woods that are hard to coat evenly with out a toner. Gel stains do a excellent job of showing off the grain on embossed metal or composite surfaces. I don't recommend using them for hardwoods, which require a good dye stain to emphasize the depth and beauty of the grain.
Sanding Sealers Are an Exciting Paint Product
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 more like varnish, but diluted with solvents to permit better penetration for priming. The hardness of varnishes and lacquers prevents them from soaking in to the wood pores. Sanding sealer provides a better adherence for clear coats.
Shellacs are often added to sanding sealers to fortify the resin and provide an instant drying agent. In addition they add an amber tone, so if you're utilizing a sanding sealer with shellac, make sure it won't have an impact on the stain. Shellacs tend to yellow aver time and contain toluene, which has a very high VOC content. Shellacs are slowly giving 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 particular primer/sealer is good for both interiors and exteriors. Pratt & Lambert's Latex Sanding Sealer has suprisingly low VOCs, but is only for interior wood and shouldn't be used under a water based polyurethane.
Oil-based sanding sealers can also be used to seal outdoor wood, especially decking, which is constantly 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 goes up, 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 utilized for priming outdoor wood.
Improved Wood and Stain Sealers for Interior Wood
Sealers, including varnishes, lacquers, urethanes, and shellacs, are put into the stain itself, applied as a top coat over 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 purchase stain/sealer combinations, they have a tendency to yellow, are difficult to keep up, and don't last as long as separately applied stain and sealers.
Varnishes contain natural oils such as Tung oil, an extremely hard, durable sealant that can be brushed on and dries slowly. Varnishes are easy to clean and maintain with soap and water accompanied by a wiped on varnish, which often keeps a wood surface looking great for years. Make certain there's no wax in your cleaner, because wax clogs wood pores. I favor to work with Hope's Tung Oil varnish for a wipe-on maintenance coating. Lacquer is a fast dry sealer that more often than not must 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 coat that permeates the wood instead of resting 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 become such popular sealers is the fact that they don't really require sanding sealers.
The odors associated with many paints and stains can be more than just offensive, they can be toxic. Solvent based varnishes, lacquers, and shellacs provide a very hard coating but contain 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 borne sealers such as Sherwin Williams Kern Aqua Lacquer average about 250 grams per liter, or 2 pounds per gallon, half the most common 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 harden or "flash off" quickly at temps greater than 60°F. The best working temperature for most water based acrylic latex polyurethanes is between 50°F and 60°F, which lets them flash a little 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 know once used water borne latex polyurethane sealer that flashed off so fast he could only put it on 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, among 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 off as they grow 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 and is also simpler to maintain as it ages. However, I prefer 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 outside stain, which make them stronger. I would recommend buying a high-end stain that is semi-transparent or what is called a trans-oxide. Until lately, the major problem with outside stains was their low UV resistance, but newer trans-oxides have finely ground metal mixed in for better protection. A higher end deck stain won't need a different sealer coating, although you can include one (such as Olympic Water Guard) if you believe extra protection is needed to fight water and sun exposure. Better deck stains retail for approximately $35 a gallon and cover 300 to 400 sq. ft.
Stay away from deck stains which 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 the deck, and many people are fooled into thinking that this is the indication of a successful coating. However, silicone breaks down quickly, usually in a matter of months, producing a discolored, waxy coat that is a pain to eliminate. The broken down silicone also ceases repelling water.
"High build" coatings such as Sikkens and Messmers work remarkably well on exterior siding, but they are too soft to be used on your deck. Eliminating these coatings requires gallons of wood cleaner and way too much work.
Water based exterior stains, such as Sherwin Williams Woodscapes, combine the features of oil-based and latex coatings. They run and drip significantly less than oil based stain, and dry out faster, allowing for two coatings the same day. Water borne stains possess the resilience and overall flexibility of any latex stain, which gives them lasting strength. They're a good choice for some applications. However that cleaning up water borne stains requires work. You can find a couple of oil components in the solvent which have to be cleaned. First use soap and water, then alcohol. Ask your dealer for specific cleaning guidelines for water based stains, and scan the label.
Ask Your Painting Professional When In Doubt
If you still have questions about which paint or stain to utilize, please ask people in the know. An experienced, proficient salesperson can clear up any questions it's likely you have. Look for a paint store with personnel having at least a decade of experience in the business. Inquire further what has worked best for your unique application and ask to see a spec sheet on the product in question.
The answers you get will rely upon whom you ask. A paint store will attempt to market you one of their products, after all, that's why they're running a business. Painting contractors may not be impartial, either. They have to sell their expertise. I get lots of cell phone calls from people hoping for aid with their painting problems. Most painters, including myself, don't object to giving an hour of time, but if you want in depth answers, consider finding a contractor for a professional analysis. Rates vary, but I charge about $60 for a written and oral examination, with respect to the traveling time involved. A paid analysis will let you know whether you should paint, stain, or re-side, as well as which covering 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
