One of the things we wanted to address with this journal was to educate our customers, so they can make the best decisions as well as having a little more understanding of a material we have all around us on a daily basis! Today’s topic is a two-part series on a topic that comes up constantly: what happens to wood as it ages? When you create a piece of heirloom-quality furniture, it is a good idea to think about how a piece will look 20, 50 or even 100 years from now. There are many factors that contribute to how wood ages, but today we’re going to look at the fundamental tendancies, by wood species.
How different woods age
Furniture looks different as it gets older. Aside from the patina, which woodworkers joke is dirt mixed with wax, there are some chemical things going on that change the look of furniture as it ages. As a Smithsonian Furniture Conservator once told me, “all wood wants to be caramel colored”. This is a reaction to light and air.
You can think about it in this way: Steel rusts and aluminum oxidizes when exposed to air and water. Stainless (!) steel is called that because the addition of exotic metals to iron protects the metal so that it ages more slowly by being less reactive.
Wood is made from a vast array or organic molecules. These molecules in wood react to heat, light, humidity, air, and all the things that touch the wood’s surface over the decades. A major purpose of finish is to provide a barrier to these things – it’s the “stainless” equivalent for wood. The type of finish and its stability in the face of those assaults change how quickly the wood reacts to its environment, and we’ll talk about finishes with respect to aging in our followup post.
As you might expect from materials that have different chemical properties, different wood species react differently to typical conditions. To extreme opposite examples would be ebony and cherry – Cherry is in a hurry to age, ebony much less so. No finish can stop cherry from reacting to light. Fresh cherry is the color of raw salmon – not a pretty picture. In six months it is a medium red, and in two years it is a glorious rich dark but variable reddy brown. Ebony looks the same at five years as at five days.
Maple turns golden, as does ash and oak; walnut actually lightens with time. Most brightly colored woods soften: purpleheart turns a mellow brown after some decades. All of the old furniture in the Louvre was once bright purple and bright yellow. A tad garish by our standards, but to 18th century royalty, it was the ultimate status symbol.
Sometimes people ask me to stain the piece I am making for them, to match their other furniture or just to be the color they want. I prefer not to, since the wood will change color with time, as will the other woods that they may be matching to. Since the finishes are different, as are the underlying woods, they will shift differently than my piece. The folks that sell kitchen cabinets in 47 different colors know that the cabinets will change color with time, but that is not their problem – it takes too long. Also, the whole room changes, so it’s harder to notice.
One thing that is very important with furniture is to not leave an object on the piece for an extended period, especially at first. This is even more important if the piece sits in direct sunlight, and exceedingly important on cherry furniture. The shadow mark from the object will be extremely difficult to remove – that doily pattern could be a permanent addition to the tabletop.
The other piece to this puzzle is the finish selection, and we’ll be back to discuss it next week.