For a job well done, wooden decks must be properly prepared and the product applied by the book. Here’s how.
How often should you repaint or restain your wood deck? That depends on a number of factors, such as exposure to sunlight and the kind of use and weather it gets. In order to know whether it’s time for a new coat, inspect it once the snow melts. Is it peeling? Is there any mould? Is it worn or discoloured? If so, then it’s time to give a rejuvenating coat; otherwise, the wood will continue to degrade – and quickly! However, it’s important not to skip a single step. Most deck-refinishing problems are the result of poor preparation or application during the wrong kind of weather.
First off, check the weather forecast before applying your finish, and do so only under the best conditions. “Never apply stain or paint in direct sunlight, which could interfere with the product’s adherence and colour uniformity,” says Josée-Ann Cloutier of Benjamin Moore. It’s better to do it in the shade or on an overcast day. Furthermore, the ambient temperature and that of the surface should be between 10°C (50°F) and 32°C (90°F) for a period of about 24 hours. Deck stains should go on only when the relative humidity is between 40 and 70%. It could take longer to dry on a muggy day, and the finish could end up somewhat dull. The drying time given by the manufacturer is for normal conditions; that is, when the temperature is 21°C (70°F) and the relative humidity is 40%. It could vary as conditions change. Don’t start when rain, dew or frost is forecast over the next three days. The coat will not stick well to humid or wet wood. It must be well dried out: the wood’s inherent humidity should be under 15%. If you’re not sure, use a wood hygrometer to precisely measure the degree of humidity in the wood.”
So, it’s a fine day and you’re ready to get started. Before you dip your brush into the can, first make sure the surface is ready. If the wood is marked, dirty, the paint is peeling or if there’s any mould, you must first remedy these problems if you plan on making it look good and having it last a long time. There are many products on the market for wood, such as cleaners, rejuvenators and strippers. Ask at your hardware store if any of these products are what you need – it’s important to ask for advice when preparing for the job.
If the surface seems to be in good shape and you’re painting or staining over an old finish, find out first how well the new coat will stick to the old one. There are two tests that Ms Cloutier recommends. First, there’s the “water drop” test. It consists of sprinkling a few drops of water over different sections of the deck. If the water beads, leave that part exposed to the weather for a longer time or sand it lightly before applying the stain or paint. But if the water is quickly absorbed, go ahead. There’s also the “adhesive strips” test. Apply some paint or stain to a small, hidden section and let dry for 24 hours. Check its adherence by pressing firmly on a strip of adhesive tape on the surface that you just did. Pull the strip off quickly. If the tape comes up clean, then the coat is adhering as it should and you don’t have to remove the old paint. But if the new coat sticks to the adhesive tape or if the old coat is pulled up by the tape, then you’ll have to remove or sand the entire surface. In some cases, you’ll need to apply a primer. Ask a paint specialist. As a last tip, you can paint a painted surface but you can’t stain a painted one.
A few tips on efficiency
“The paintbrush is the best tool for spreading paint or stain on a deck,” says Ms Cloutier. “For best results, the experts recommend using a natural bristle brush for oil products and a synthetic-fibre (nylon) brush for acrylics. If you use a roller, I suggest making another pass with the brush to make sure the stain or paint permeates.”
She also recommends applying a coat of the product on all wood surfaces – where possible – while paying particular attention to the ends of the planks. “Rough ends absorb a lot of humidity and split, which can make the wood difficult to cover,” she says. To avoid leaving overlap marks of paint or stain, spread the product in the direction of the grain and from end to end across the entire length of the deck. Do the same to the next plank. Allow the surface to dry for at least 48 hours before walking on it and wait at least 30 days before washing, so that the new coat will thoroughly cure.
Finally, make sure you buy enough stain or paint to cover the whole area. If you do have to buy another container of the same colour to cover the same section, try to get one that comes from the same lot. And here’s a little trick for keeping the colour uniform: when there’s just a quarter of a container left, add product from the new can and blend the two together well. And, of course, don’t forget to stir the paint or stain from time to time during use.
Original article by Jacqueline Simoneau
Translated by John Woolfrey