If you have a wooden gazebo, you may be trying to decide how to finish the wood. It doesn't matter which type of gazebo you have, it could be a canvas gazebo, a garden gazebo, or a canopy gazebo. As long as you have wood on your gazebo, either as a frame, or a wooden floor, or railings.
You will have several choices as to how to finish your wood. You could, of course, use no finish at all on your gazebo. Any wood left to the weather will turn gray within a year or so. The gray color is actually a thin layer of partially deteriorated wood fibers. Further withering causes loss of these fibers, but the process is so slow that you don’t need to really worry about it as long as the wood dries before fungi takes up residence. Vertical boards that allow water to run off fare better than horizontal boards, and sunny spots are better than shady spots. Mildew is another problem that can attack damp, unfinished wood. While mildew doesn’t rot the wood, it is unsightly.
One of the functions of a wood finish is to partially seal the cut ends of the wood cells to inhibit expansion and contraction caused by moisture moving in and out of the wood. The expansion and contraction causes cracking, twisting, splintering, and cupping.
Lighter-weight woods are less susceptible to these problems, making an unfinished cedar railing fare better than a railing of unfinished, pressure-treated, southern yellow pine.
Varnish is not generally recommended for outdoor structures. It forms an inflexible film that cracks when wood expands and contracts, causing the finish to peel when water gets under it. However, there is one exception. You may consider using a good marine varnish on mahogany decking boards that are protected from the weather
For most parts of your gazebo, you have four finishing choices: 1. Do nothing, 2. Apply a preservative, 3. Use a Stain, 4. Paint.
You should use wood preservatives when you want to maintain the natural color of the wood. The least expensive formulations are basically paraffin or some other wax dissolved in mineral spirits. They don’t do much to retain the wood’s natural hue. As the wax soaks into the cells of the wood to clog it up and the mineral spirits evaporate.
You can use these formulas on pressure-treated wood when you want to lose the green tint and want the wood to turn gray. For more money, you can buy a preservative formulated to block ultraviolet (UV)light. It’s the UV rays that destroy the surface fibers and turn wood gray. Always use UV-blocking formulas when you want to preserve the color of redwood or cedar. Other additives found in wood preservatives include fungicides and products that reduce mildew. It is always a good idea to use one in damp locations.
Like varnish, paint forms a film on the surface of the wood rather than penetrating the cells of the wood. But paint is more flexible than varnish, allowing it to stretch and contract with wood movement. Paint also blocks the UV rays that deteriorate surface fibers. This is an important characteristic of paint since it won’t adhere to gray, weathered wood fibers.
Most paints today are either alkyd oil based or water-based latex. Traditionally, the durability of oil-based paints made them preferable. But recently, because of concerns about volatile organic chemicals(VOC), paint manufacturers have put a lot of resources into improving latex paints. Besides greatly reducing the VOC’s released into the air, the big advantage of latex paints is that you can clean tools, brushes, and your skin with water. Oil-based paints require mineral spirits for cleanup. One exception: the Western Red Cedar Association recommends using an alkyd-based primer on cedar, although they acknowledge that there are latex primers designed to go over cedar. The most important thing to remember about primers is to use one. Primer is essentially the glue that holds paint to new wood. If you skip the primer, the paint will surely peel. Make sure to use enough primer to obscure the grain. Then give the wood two coats of exterior paint.
Floor paint, one type of speciality paint, is worth your attention. As the name implies, this type of paint is made specifically to stand up to foot traffic. All the floor paint I have seen is specified for interior or exterior use. Always check the label to make sure before choosing one designed for your outdoor structure. A good floor paint will contain epoxy that makes the surface really tough and long-lasting.
Stains for outdoor use can be either semi-transparent or a solid color. Both have an oil or resin base that penetrates into the wood, much like a preservative. The colors come from pigments that stay on the surface as the stain soaks in. Stains are available in a wide range of colors.
Semi-transparent stains, as you would expect, contain less pigment so that the grain of the wood isn’t hidden. Solid stains leave enough pigment to obscure the texture of the grain without completely obscuring the texture of the wood. With solid-color stains, the oil or resin doesn’t penetrate as deeply into the wood as it does with the semi-transparent stains.
I find that stains, especially the semi-transparent variety, look best on woods with an open straight grain, such as cedar. Smooth pine trim boards sometimes absorb the stain unevenly, which can look blotchy. You can help prevent this problem by penetrating the lumber with a paintable wood preservative. In my opinion, the grain pattern on most pine that you find in lumberyards today is not distinctive enough to highlight with stain anyway.
Because stains are absorbed into the wood, they won’t eventually peel like paint. Also, unlike paint, adding additional coats of stain won’t cause a buildup that eventually must be removed. The trade-off is that stain is less durable than paint and must be recoated more often.
You can see that you do have a choice as to the finish of your wood. I used paint on my gazebo and have been happy with the results. yardandgardenrescue.com offers tips and information concerning all aspects of owning a gazebo, especially a canopy gazebo.