Basic Information of Wood | Protecting and Beautifying Wood through Paint | Painting on Wooden Interiors and Furniture | Painting for Exterior Woodworks | Basic Wood Painting Techniques
 What is the definition of wood?
Wood is a biological material with widely different properties depending on the species, geographic area where the tree is grown, the growth conditions, size of the tree at harvest, sawing, and other manufacturing processes.
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Why does wood change in size?
Wood changes in size when the environment it is in changes. This is because wood dries when the moisture in it leaves by evaporation. When freshly cut from a tree, it has a lot of moisture (Green-wood). The moisture is both bound (in the cells) and free (surrounding the cells). The free moisture evaporates first. When the wood is at about 20% moisture content, most of the free moisture is gone. Now the bound moisture evaporates. When this happens, the wood cells start to shrink. When the cells shrink, the wood gets smaller. The cells keep losing moisture until the moisture in the cells is balanced with moisture in the air surrounding the lumber. In the tropics, wood will only dry to 15% moisture content. In hot, dry climate it could go to 2%.
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Why do we need to protect wood?
 Although wood is naturally durable and strong, we need to protect it because the effects of outdoor exposure on wood can degrade not only its physical properties, but its natural beauty as well. Wood exposed outdoors is subjected both to rain (moisture) and sun (ultraviolet radiation), two major factors that can ultimately cause wood to lose both its natural beauty and strength.
Morning dew, rainwater and melting ice or snow are quickly absorbed by unprotected wood, causing it to soften and swell. Direct exposure to the sun's heat causes drying, which makes wood shrink. Continuous cycles of wet and dry, swelling and shrinking, cause wood to warp, split, crack and check - all of which lead to premature wood degradation and expensive repairs.
Unprotected wood is also subject to surface graying caused by constant exposure to the sun's ultra-violet rays. Persistent moisture exposure creates ripe conditions for the growth of mildew, mold, algae and other fungal organisms that feed on wood, eventually spreading across and staining the surface. Termites and other wood boring insects also use wood for a food source, causing ultimate wood rot and decay.
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