Flexner on Finishing: Finishing Cherry
Aging and Darkening
Besides blotching, another quality of cherry is the tendency of its heartwood to darken as it ages. The darkening is brought about by exposure to oxygen and light. Light accelerates the process, especially UV light, such as sunlight and fluorescent.
As cherry darkens, the blotching becomes muted – that is, the lighter non-blotchy areas darken to the color of the darker blotchy areas. So time does a pretty good job of disguising blotching in cherry. This is the reason I’ve always believed that the best way to finish cherry, if your goal is to make it look like old cherry, is to let it get there naturally.
You can always accelerate the darkening a little by placing the ready-to-finish or already finished wood in the sunlight for a few days. This will darken the heartwood a little, but it will still take years to reach the rust red color of old cherry.
If you want to achieve the rust-red color immediately, and are using non-blotchy cherry or are willing to live with the blotching, the most accurate way to do so is to stain the wood with a cherry dye stain. But keep in mind that the wood will still darken under the stain, giving you a result you, or your customers or descendents, may not be so pleased with after several decades.
How Factories Do It
If you’ve ever looked at factory-finished cherry furniture, you’ve surely noticed that it doesn’t look like old cherry. It’s usually considerably darker, sometimes so dark and opaque it’s even difficult to see that the wood is cherry. But it’s not very blotchy.
Cherry furniture manufacturers solve the blotching problem by putting most of the color on top of the wood rather than in it. Instead of using stains, they get the color with glazes and toners. Glazes are thickened stain applied in between coats of finish. Toners are the finish itself with the color (usually dye) added. Toners are always sprayed.
The end result is reduced blotching because it is covered over. Though there’s no reason you couldn’t finish cherry in this manner yourself, the look attained is not what most woodworkers want.
Here’s the bottom line on cherry: Most boards blotch when stained, and also when finished without a stain. There’s no way to avoid this, other than finding boards (or veneer) that don’t have the tendency.
Over time the blotching is muted as the heartwood darkens naturally to a rust-red color. If you choose, you can get to this color immediately by staining with a cherry-colored dye stain. But in time the wood will darken further underneath the dye.
You can also add color and disguise the blotching with glazes and toners, but you can’t achieve the rich, transparent rust-red look of old cherry this way.
The only way to get the old cherry look is to finish with just a clear finish, any clear finish, and let the wood age naturally.
From the February 2009 issue #174
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