There are three basic clear finishes for outdoor furniture: exterior oil, exterior varnish, and an epoxy sealer with an exterior varnish topcoat. Though it’s termed a surface-building finish, most of the first coat of polyurethane is absorbed into the wood. A stiff, non-ferrous bristle brush may be used to remove surface dirt, dust and loose wood fibers before applying the stain. They make outdoor wood look as refined as furniture, allowing grain patterns to show through added colour. Through a process called photo-degradation, ultra-violet (UV) radiation damages the wood and the finish. Before you change to the next highest grit, you must clean the surface of the wood.
Finishing outdoor wood furniture will not only beautify it, but also extend its lifespan by many years. US Coating Solutions’ wood siding restoration, staining and protection system provides a very cost effective solution to restore wood siding to its beautiful, natural look that will last a lifetime!! Architectural coatings available for wood generally include paints, stains, varnishes and water repellents. Left unfinished, this wood resists rot and insects, but does not resist UV degradation.
Some of the most dazzling and renowned wood finishes in the world have historically been from padding very thin coats of shellac onto the surface of the wood (a technique called French Polishing ) until an immaculately clear shine emerges. Note that weathering only occurs on the surface of wood, usually at a depth of 0.05 to 0.5 mm. As long as decay doesn’t start, weathered wood will still be completely serviceable for years. Begin by inspecting your outdoor wood furniture to see if any repairs are required. Refinishing with ArmorThane leaves the wood intact and eliminates the need to replace or cover the floors.
Contains UV absorbers that protect the finish and the wood from the sun’s rays. It is highly UV resistant providing long term protection for the wood and the coating. Figure 1. While traditional water-repelling clear finishes allow wood to gray from the sun, colored products block UV-rays for further protection. Second, wood has properties that sheet metal does not, like moisture transfer (in or out of the wood).
More recently, it’s gained favor over linseed oil for wood finishing because it is faster drying and does not darken as much with age. As the binder breaks down over time (mainly from UV damage), the pigments wear off and increasingly expose the wood surface. They are brushed on wet and given time to soak into the top layer of the wood before the excess is wiped off.
Because its essentially just clear paint, it does an excellent job of protecting the wood and preventing moisture from getting in. I never tried the stuff myself but some folks raved about it. I can’t imagine why an automotive topcoat wouldn’t accomplish the same thing. There are many transparent products marketed as providing water protection for wood (water repellents) – these might technically be considered wood treatments” rather than wood coatings as they mainly provide water protection and help reduce checking (splitting), and have very limited, if any, UV protection. Flex-Clear Urethane provides a long term solution for wood protection that looks great for many years!!
Semi-transparent stain does go into the wood and does not form a film on the surface, but unless it has specific water repellent additives in it, it will colour the wood but not moisture-protect it. In the 1970s, coatings formulators began using UV additive in finishes called ultraviolet light absorbers (UVAs) and hindered amine light stabilizers (HALS). Varnish is very similar to paint, however, it contains no pigment and so is ‘see through’ revealing the underlying beauty of the wood….initially.
The protective coating must also incorporate water repellents, UV absorbers, translucent pigments, must be fade resistant, stay flexible and give long term protection and of course needs to be easy to apply. UV light causes degradation of the surface of the wood and depolymerisation of a film. All doors with resin panels come standard with a protective film that must not be removed until after door finishing is complete and the door is fully installed in its final location.
The samples which were sealed with linseed oil first lasted much better than the samples which were applied directly over bare wood. Ultraviolet light absorbers (UVAs) have the task of protecting both the wood and coating by absorbing the harmful wavelengths of light and converting it to heat. Tung oil (china wood oil) received wide application in China: in the building trades as a treatment for both stone and wooden structures; in marine trades as a preservative and water repellant on wooden boats. To stop this degradation a protective coating needs to be applied to the surface of the timber.