If you’ve worked with lumber for any length of time, you probably already realize that color-matching lumber is almost like an inside joke within the industry. Despite the modern preference for precise color-matching, it really does clash with the equally trendy concept of using environmentally friendly materials such as real, natural wood. If it’s more important to you to make sure you’re using truly green materials than it is to have Pantone-perfect color matching, then real lumber is the way to go. But that doesn’t mean that you can’t still achieve a level of color-coordination: by understanding the factors that contribute to color change in lumber, you’ll be better able to create a more consistent appearance without sacrificing environmentally friendly practices.
The Reality of Lumber Color Change
Here’s the basic idea: all lumber species will change color after being sawn. While the most significant color change may occur immediately following milling, their color will continue to change throughout the years. Oxidation plays a role, as does sunlight, in the color-changing process. Some species also undergo chemical changes, causing even more significant color change. What this means for color-matching may be obvious, but as your lumber continues to mature, its color will continue to change, directly affecting the degree of color matching that it exhibits. Usually, the maturation process will mean mellowing of color distinctions and blending of differences.
The Fact of Lumber Graying
Over time and especially with exposure to the elements, exterior lumber will eventually turn gray. Sometimes customers will request that a new exterior structure be built to match the existing gray wood. While silvery gray wood can be re-cut or re-planed in order to remove the gray outer layer, making new wood appear aged can be tricky. Some species take longer than others to naturally take on a silvery hue; tropical lumber species contain high oil content, keeping them from graying as early as other species.
The graying is caused by the sun’s dual roles of drying out and bleaching the surface of the wood. Any oil or resin in the wood will produce a natural resistance, and artificially adding decking oil can further hold off bleaching. (On a side note, if you see anyone advertising a decking product as completely “maintenance free,” their assumption is that you’re okay with a gray deck. If you want to keep your deck from graying, you will need to periodically re-apply oil to the surface.) You’ve probably noticed that, in addition to color, aged wood also takes on a different texture from freshly milled wood. Due to the sun’s drying effect, tiny surface cracks, or checks, typically occur. As wood dries quickly and unevenly — as it always does when exposed to direct sunlight — these checks are inevitable.