Understanding Lumber Color Change - Part 1
For centuries. J. Gibson McIlvain Lumber has been studying and celebrating one of nature’s most useful products. We truly believe that natural wood is preferable to composite materials, and it’s certainly the most environmentally friendly building material around! At the same time, though, there are some specific considerations to keep in view when working with natural materials.
One unique aspect of wood is that it moves; another is that it changes color. Not only is there quite a range of coloring within particular species, but all woods endure color change both between the milling and building stages and throughout the lifetime of the lumber. Much of this color change is due to fading when exposed to sunlight, while some can be caused by chemical changes.
We’ll look at some of the visible changes you can expect as your wood for a deck, hardwood floor, furniture, or other project matures.
Just about any wood will take on a silvery gray hue when exposed to the elements. Basically, what happens is that the sun bleaches the surface and dries it out.
Some species experience graying more rapidly than others; often, tropical species with high oil and resin contents resist graying for some time. Artificially adding oil to wood can help prevent bleaching, as well. The outward layer can be removed through cutting, sanding, or planing, but otherwise, the gray coloring is there for good.
Knowing this is important for those who don’t want their exterior wood projects showing their age — er, um, maturity. Whenever an exterior wood product is touted as being “maintenance free,” the assumption is that you’re okay with graying; if you’re not, maintenance will be necessary.
As the sun bleaches and dries the wood, tiny surface cracks, or checks, often appear. Particularly common for wood that’s exposed to intense direct sunlight, checking is caused when wood dries quickly and unevenly. While it isn’t actually a defect in the wood, it can appear that way to some.
Factors that will influence the amount of checking your exterior project will exhibit include the local climate, time of year, and amount of direct sunlight to which the wood will be exposed. Of course, oil and resin can help prevent or reduce checking, just like it can guard against bleaching.
In our instant-gratification society, it can be frustrating for those looking to match new exterior projects with the pieces that have already matured.
While the natural weathering process can help a new exterior structure grow to match older pieces that have already gone gray, you can also speed up the process. Some bleaching oils can help the process along, but sometimes they create a different look than natural weathering produces. The combined forces of UV light, heat, water, and wind simply can’t be rushed or fabricated.
Continue reading with Part 2.