THE FUNCTION OF STAINS AND PAINTS - PART II
This is part two of a 2 part series of articles on paints and stains.
High Demand 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 would last longer. It may endure longer, but as I found out when I needed to touch up the ceiling only 2 years later, exterior paints will discolor on an inside surface. Exterior paints contain special additives made to withstand the outdoors. 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. In fact, 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 line created by Benjamin Moore, are created with no VOCs at all. 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 level of popularity for interior applications, especially for walls and ceilings. Alkyds stay the professionals' choice for trimming work because oil based paints are much easier to paint on detailed areas like molding and trim. However, that traditional school of thought is gradually changing as better latexes, including Pratt & Lambert's Accolade Interior Acrylic Semi Gloss, come on the market.
High Demand Exterior Paint Coatings
Moisture is an important consideration for exterior paint selection. Every day a family group of four will generate several gallons of vaporized water in the house.
Coupled with naturally occurring humidity, this may mean a a large amount of moisture moving through the walls and siding. Moisture is highest in the baths and kitchen. If these rooms aren't sufficiently ventilated, water will migrate through the wall space. Vapor barriers help to contain wetness, but vapor always seeks to escape. The structure of a house, the sort of vapor barrier it has, ventilation, and dampness all make selecting 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 go 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 favor using latex on all exterior surface areas, including wood siding, stucco, and masonry. Latexes resist fading better than most oil-based paints, and they'll cover either oil-based or latex primer (most oils have to go on top of an alkyd primer).
Latexes perform a great job of covering concrete. Despite its hardness, concrete is very porous, and oil-based paints don't always adhere well. For ideal durability, I would recommend latex enamel.
In general, if I know of a latex product that will provide superior performance, I will choose it over an oil-based product that must be cleaned with a thinner.
Latex only requires water. Thinners add yet another expense, are hard to get rid of, and usually finish 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's nothing mysterious about them. The bottom line in figuring out which stain to utilize is to familiarize yourself with the product lines available. Scan the label, along with any product information you can get, and speak 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 higher wood penetration. Waterproofing is a priority with exterior stains. Most include built-in sealants to increase durability 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 coating. 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 draw out the richness of the grain. Others contain only pigments, which are better to apply, blend, and touch up. Pigmented stains are lighter in color and bring out more of the wood grain. If you're looking for darker results, a dyed stain will provide what you would like in one coating (be 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 require touching up, so be sure to consider the ease of maintenance in your selection 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 steer clear of the watery nature of stains, get a gel stain, which has had almost all of the liquid solvent removed. Gels are simple to use. They wipe 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 troublesome to cover 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.
Learn How to Use 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 allow 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 strengthen the resin and provide an instant drying agent. They also add an amber tone, so if you're using a sanding sealer with shellac, make sure it will not influence the stain. Shellacs tend to yellow aver time and contain toluene, that 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 likewise have high VOCs, although less than their shellac based cousins. Pittsburgh Paints makes a slow dry alkyd resin sanding sealer without shellac named Rez 77-1. This specific primer/sealer is wonderful for both interiors and exteriors. Pratt & Lambert's Latex Sanding Sealer has very low VOCs, but is strictly for interior wood and shouldn't be used under a water borne polyurethane.
Oil-based sanding sealers also can be utilized to seal exterior wood, especially decking, which is continually subjected to sun and water. For color consistency in areas like decks, you need 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 outdoor wood.
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 coat on unstained wood trim. They could be used for any type of trim, including windows, doorways, 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 completely clean and keep maintaining with soap and water followed by a wiped on varnish, which often keeps a wood surface looking ideal for years. Make sure there's no wax in your cleaner, because wax clogs wood pores. I prefer using Hope's Tung Oil varnish for a wipe-on maintenance coat. Lacquer is a quick dry sealer that almost always needs to 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 coating 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 that they don't really require sanding sealers.
The smells associated with many paints and stains can be more than simply offensive, they can be toxic. Solvent based varnishes, lacquers, and shellacs give a very hard covering 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 most common VOCs of oil-based lacquers. The ethers in water based sealers aren't combustible, another advantage, but they still have sufficient VOCs to warrant a respirator.
Although they resist yellowing, water borne sealers such as acrylic latex polyurethanes do tend to raise the grain. They'll also set up or "flash off" quickly at temperatures greater than 60°F. The very best working temperature for nearly all water based acrylic latex polyurethanes is between 50°F and 60°F, which lets them flash a little more slowly. In this case, 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 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, and others.
Stains and Sealers for Exterior Applications
Due to their better penetration and sealing power, most exterior stains sold today are oil-based. However, oil-based solid stains peel as they grow older, making them more challenging to maintain. A solid stain is similar to 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 exterior stain, which make them stronger. I would recommend buying a high-end stain that is semi-transparent or what's called a trans-oxide. Until just lately, the major problem with exterior stains was their low UV resistance, but newer trans-oxides have finely ground metal mixed in for greater protection. A high end deck stain won't need a separate sealer overcoat, although you can include one (such as Olympic Water Guard) if you think extra protection is required to combat water 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 are not 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 the indication of an effective coating. However, silicon deteriorates quickly, usually in a matter of months, producing a discolored, waxy coat that is clearly a pain to eliminate. The broken down silicone also stops repelling water.
"High build" coatings such as Sikkens and Messmers work remarkably well on outside siding, nevertheless they are too soft to be used on your deck. Removing these coatings requires gallons of wood cleaner and way too much work.
Water borne exterior stains, such as Sherwin Williams Woodscapes, combine the advantages of oil-based and latex coatings. They run and drip less than oil based stain, and dry faster, allowing for two coatings the same day. Water borne stains have the resilience and overall flexibility of your 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 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 directions for water borne stains, and scan the label.
When In Doubt, Ask Your Painting Professional
In the event that you still have questions about which paint or stain to use, don't hesitate to ask people in the know. A skilled, knowledgeable salesperson can clear up any questions you might have. Choose a paint store with staff having at least a decade of experience in the business. Inquire further 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 rely upon whom you ask. A paint store will try to sell you one their own products, in the end, that's why they're in business. Painting contractors may not be impartial, either. They need to sell their know-how. I get plenty of telephone calls from people seeking help with their painting problems. Most painters, including myself, don't mind giving one hour of time, but if you need in depth answers, consider hiring a contractor for a professional examination. Rates vary, but I usually charge about $60 for a written and oral examination, depending on the driving time included. A paid evaluation 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
