Adding Age to Cherry

My favorite piece of furniture in my home is the antique library table that serves as my desk. There’s nothing particularly impressive about the design, but the wood is gorgeous cherry that glows with inner fire. In fact, after intensifying for more than a century, the color is much closer to rich sherry than raw cherry. And that’s one of the qualities that makes cherry such a popular choice among American hardwoods – its looks improve with age. But therein lies the problem: New pieces of cherry furniture can appear anemic, especially with just a clear finish on them. Instead of a warm rust-red, you’re more likely to see washed-out pink or even a gray cast. It takes years for cherry to age into a natural beauty.

If you’ve worked much with cherry, you know how finicky – not to mention expensive – it can be. Not only is it prone to sudden grain reversal – and thus tear-out while working it, you can’t always tell by looking if a board is going to finish well. The last thing you want is a blotchy mess after you’ve spent hours in the construction process. A board that appears clear and straight grained may soak up stain in an unpredictable (and unattractive) pattern.

It’s Worth the Wait
That’s why some woodworkers contend that the best finishing method is to simply wait a few decades and not try to fake what it takes nature years to create. But because most of us would prefer to have our projects looking good from day one, we experimented with a number of methods designed to mimic the aging process, then lined up the sample boards side by side to determine which we liked best.

Our decision was based purely on the personal preferences of our editorial and art staff, taking into consideration that the wood’s color would continue to deepen over time.

In the book “Understanding Wood Finishing” (Reader’s Digest), Bob Flexner writes that, “old cherry that has darkened naturally is actually quite impossible to match with stains or toners. The color can be matched well, but neither the stain nor toner can recreate the translucence of naturally aged cherry.”

That’s why, with one exception, we eschewed stains and toners – we had no wish to cover the beauty of the natural wood, or produce a finish that would be compromised years from now after the wood has aged gracefully. Our goal, in effect, was to create a good fake I.D. – something that will fool people until the wood’s chronological age catches up to its stated age.

The Contestants
After first selecting sample boards similar in appearance then preparing each for finishing in the same way, we tried exposure to sun, exposure to sun after a coat of boiled linseed oil, natural Danish oil, a mixture of natural and dark walnut Danish oil (the exception), clear shellac, orange shellac, garnet shellac, lye, and potassium dichromate. For each method, we followed the instructions on the container. When dry, each sample board was top-coated with an aerosol spray lacquer so that the sheen on each was as similar as possible.

The clear shellac looked little different than the naked board, which is to say not very pleasing or even worth the effort. The other two types of shellac resulted in finishes of remarkably similar appearances, which, while not unpleasant, did not resemble aged cherry. Instead of bringing out the natural beauty of the wood, they merely reflected the color in the flakes. In addition, each type of shellac resulted in a fair amount of blotching – obviously undesirable but something that can appear in cherry with any film finish.

Like the natural shellac, the natural Danish oil created little appearance of aging. The mixture of the natural and dark walnut Danish oils resulted in a color that while pleasing, was lacking in red tones. One of our editors has in the past achieved good results on cherry with the mixture; it’s possible that the boards we selected were simply recalcitrant – a not uncommon problem with the species.

When working with both lye and potassium dichromate, it’s important to follow strict safety precautions. Lye can cause serious chemical burns to your skin, and potassium dichromate is considered a carcinogen, so wear a mask to avoid breathing the powder. Also, it’s important to neutralize the lye by washing the wood afterward with a weak white vinegar solution – otherwise, the reaction could be re-started should water get through your topcoat in the future. Both cause chemical reactions with the wood, the results of which will vary depending on the strength of your solution. Because results will vary, you may wish to experiment. We tried both methods twice, the first time combining the powders with tap water, the second time using filtered bottled water.

With the lye, the results were similar in both instances. Combining approximately 1/2 teaspoon of powder with one quart of water, then brushing it over the wood resulted in a rich red color that developed overnight. While it looked nice, it also looked much like mahogany. In addition, because the wood will continue to naturally darken in color as it ages, if the initial treatment is too dark, it may eventually be unrecognizable as cherry, which would defeat our purpose here.
Unlike the lye, the two mixtures of potassium dichromate looked completely different. Combining approximately an 1/8 teaspoon of powder with tap water produced overnight results that resembled dirty walnut more than aged cherry, while the bottled water mixture produced a color just a shade darker than the clear shellac – which is to say little color at all.

And the Winner Is …
What we think produced the best result was boiled linseed oil and a day in the sun. Or, lacking a sunny day, a session at the tanning salon. Of course, you’re unlikely to find a tanning bed with the capacity to hold your highboy, so you’ll simply have to wait for the clouds to clear. On the sample boards pictured on the “Contents” page, we simply placed the boards on sawhorses outside our workshop on a sunny day. While it’s relatively easy to produce an even tan on a flat piece of wood or a small piece that creates few shadows, it’s likely to be a little trickier with a large project. The good news is that repeated sun exposure over several days didn’t result in a noticeably darker tan than what we achieved for our dining room tray with one tanning-bed session, so if you face a different side of your piece into the sun on subsequent days, you should end up with even coloring.

Why? The color change that takes place in cherry exposed to the sun is a continuous thing that’s going on, explains USDA Forest Products Laboratory expert Mark Knaebe.

“It’s a logarithmic rate of change, kind of like a nuclear half-life. It starts out fast and then slows down,” which gives the “untanned” area time to catch up, he said.

While all wood is in some measure chromophoric (meaning it changes when exposed to light), cherry has a more immediate and noticeable reaction to ultraviolet (UV) light than do most other domestic hardwoods. But, says Knaebe, moisture and oxygen are also necessary for the reaction to occur. If you were to build in a vacuum, the color of your wood wouldn’t change.

A more practical way to keep the color of your cherry constant, if that’s a look you like, is to use a pigment stain, says Knaebe, which in effect acts as a blocking agent. Unlike dye, which is made from organic chemicals that break down over time in the light, pigments are basically bits of ground up rock, which lasts a lot longer. But as Flexner argues in his book, while you may be able to achieve a pleasing color, you won’t be able to mimic the glow that comes from within naturally aged cherry.

Achieving the ‘Perfect’ Results
To achieve our “perfect” results (which we decided were the best balance of current beauty and expectation of future good looks), here’s how to proceed. First, prepare the surface to be finished using progressively finer sandpaper, up to #220-grit, or plane it smooth. Then, mix two parts boiled linseed oil with one part mineral spirits (try to mix only enough for each application). The mineral spirits thin the mixture and make it easier to apply.

Apply a generous amount to the raw wood using a rag, foam brush or one-use bristle brush, and allow it to soak into the surface for five to 10 minutes. Then, wipe off the excess oil with a dry rag. We placed our sample board in the sun immediately and left it there for eight hours. The dining room tray cured overnight before its 20-minute tanning session. Both resulted in almost the same amount of color change, and additional sun exposure had no noticeable added effect. After waiting a week for the oil to cure, we sprayed on a top coat of lacquer.

Dispose of excess oil/mineral spirits by soaking up the remainder with a rag or rags, then set the rags out in a single layer to allow the oil to cure. We generally set the rags out on the rim of our garbage can. If you bunch up the rags when they are soaked in oil there is a danger of spontaneous combustion as the oil cures. Once the rags feel dry (usually overnight in a warm room), it’s safe to throw them in the garbage.

Bask in the Sun
In the end, we agree with current dermatological wisdom – lazing around in the sun adds age to your bits and pieces. But for the purposes of  making your cherry look nice, that’s a good thing. So go ahead and slather on the oil. WM

Megan Fitzpatrick is editor of Popular Woodworking Magazine.

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