Choosing Custom Wood Color

Light Changes the Color of Wood Finishes-Be Aware When Choosing Custom Color

When you choose the color and sheen of your custom made architectural millwork the last thing you want is a change in the color six months or even six years later. The fact is that light changes the color of finished wood as well as unfinished wood. The net change you will typically see is negligible because of the modern high tech finishes now used in custom cabinetry. But it is smart to allow for a slight shift in hue over time so be aware: Dark woods such as walnut usually lighten slightly; some dark woods such as cherry and mahogany darken; many light hard-woods such as oak, maple, birch, ash and poplar change very little. Woods such as pine darken but at abaico we do not use pine for custom woodworking.

Woods and finishes are organic materials, which, like all organic materials, change color when exposed to the elements. It's important to understand what's happening so you can try to slow the change.

Because walnut lightens, exposed wood may over time, show the effects of fluorescent or natural lighting. Direct sunlight hitting walnut paneling would have caused the same to happen but more dramatically. Normal light coming through windows has much less impact.

The primary source of color in wood is extractives. These are non-structural elements that give a distinctive coloring to various species of wood: walnut, cherry, oak, etc. When the extractives on the surface of wood are totally washed or bleached out, only the cellulose is left. It is light gray or white, the color you see in wood that has been exposed to the outdoors for several years.

Boat owners will pay almost anything for a varnish that requires less maintenance, so they are getting the best that can be made. And still the UV blockers are broken down by sunlight and the boat owners have to sand off deteriorated topcoats and recoat every year or two, depending on the degree of light exposure.

Interior objects aren't damaged nearly as quickly as boats because glass windows block some of the UV rays from sunlight, and fluorescent light isn't as damaging as direct sunlight. But the UV blockers still lose their potency and cease to be effective so color shifting should be planned for.

The type of light responsible for the greatest impact comes from the ultraviolet (UV) end of the spectrum, and the biggest offenders are sunlight and fluorescent light. Color change caused by incandescent light (regular light bulbs) is much slower.

To put this information to use, you may want to choose a finish for the color it will add to the wood you're finishing. For example, if you're finishing maple and you don't want any yellowing, you would choose water-based finish first, then conversion varnish or CAB-acrylic lacquer.

At the abaico wood shop we like to use water based, non-toxic, non-grain-raising (NGR) dyes because they are more resistant to fading than other dyes.

The cause of color change is oxidation, the natural chemical process but using the proper finishing products, the process is terminated for all intents and purposes. Abaico will always choose a toner and finishing system to match the conditions present in the home or final location of the project to negate most color change effects.

The word "finish" can refer to a clear coating, or it can refer to a coating in combination with a stain, or a coating with colorants added, such as toners and glazes. Clear finishes vary in initial color and in how fast they darken as they age. Water-based finishes have no significant color when initially applied, and don't "yellow" as they age. Oils and varnishes begin with the most color and yellow the most as they age.

High quality finishing like we do for our custom made furniture grade projects at abaico requires the use of conversion varnish and CAB-acrylic lacquer, which yellow very little; water-white lacquer, which yellows slightly more; pre-and post-catalyzed lacquer, which yellow still more; and finally, nitrocellulose lacquer.

Shellac comes in various shades from light yellow to orange and continues yellowing very slightly as it ages.So the finish on the walnut paneling exposed to the fluorescent lighting probably yellowed a little simultaneously to the wood becoming lighter. When you are trying to match a color on an old finished object, you often have to take into account a slight yellow caste.

The fade factor

Much more susceptible to light than the finish itself are the colorants used within the finish, especially dyes. All dyes fade fairly rapidly in sunlight and slightly less rapidly under fluorescent lights. By "fairly rapidly," I mean you will notice some fading within six months to a year.