| Handmade Guitar, Part 13: Wood Finish |
From "Handmade Music"
episode DHMM-104 |
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Host Jeff Wilson with luthier Lynn Dudenbostel, the creator of the guitar featured in our series.
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"It's not how much varnish you put on a guitar," says Dudenbostel, "it's how much you leave on."
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The timber from this giant red spruce tree provided the top for the guitar Lynn has built.
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This episode of DIY's Handmade Music brings to a conclusion the four-episode guitar-building series. Featured in this episode is the precise application of a sophisticated wood finish to the instrument. It's an alchemy of applied elements, but luthier Lynn Dudenbostel shares a secret. A good finish is the result of what he removes not what he applies. As he says, it's not how much varnish you put on a guitar, it's how much varnish you leave on a guitar. The show then goes back to the Nashville recording studio where Cody Kilby, guitarist for bluegrass band Kentucky Thunder, gets to take the newly completed Dudenbostel guitar for a trial run. And just to insure a passing grade, host Jeff Wilson asks the expert on vintage guitars, George Gruhn, to evaluate the finished product. In this segment, Lynn Dudenbostel reveals the various techniques he employs to finish this guitar, following in the traditions of master guitar builders. Materials Drill press
Paint sprayer
Water-based stain
Varnish
Lacquer
Tuners
Spray booth
Protective gloves
Safety glasses or goggles
Respirator Safety Alert: Always wear safety goggles or safety glasses when
working with stains, varnishes, solvents and other toxic chemicals. When working with chemicals that give off toxic fumes, wear a respirator.
The process thus far has consisted of first building the guitar body (top, back and curved sides) from red spruce and rosewood, and then carving the neck from solid mahogany. With those two main elements built, it's now time to apply a finish. "You have a neck that's pretty much complete, and a body that's complete," says Dudenbostel, "and it's time to finish those. And in the case of a guitar, unlike a mandolin, I finish these separately and join them together later -- mainly because this is the way it's done traditionally. Tradition has a lot to do with why we do certain things and when we do certain things."Finish for the Guitar Neck - The first step is to stain the neck. Mahogany responds beautifully to Lynn's mixture of walnut and dark brown dye so one even coat is all that's needed. Dye is a good choice for necks because the water-based type Lynn uses here doesn't fade with age. Lynn applies dye with a cotton rag (figure A).
- With an even coat applied Lynn uses the spray booth and sprayer to add a sealer-coat of lacquer to the neck (figure B). Again, one coat will do the trick. Lynn has learned over the years to be thorough with finish, but he's careful not to apply too much of anything.
Once the lacquer is dry, Lynn he adds a personal touch to the instrument -- the "Dudenbostel" logo (figure C). The name on his guitars (figure D) reveals the maker, but that name also stands for craftsmanship unmatched since the "golden age of guitar-making" before World War II.
Once the finish has been applied to the neck, there's a bit more work to be done to prepare the neck for the installation of the tuners. Once installed, the tuners (figures E and F) will be used by the musician to adjust the tension on the strings, thereby altering the pitch of the notes that each string makes.
Using a template from a vintage guitar Lynn marks the location for the tuners onto the face of the peg head (figure G). The tuners connect the strings to the peg head. Using the drill press, Lynn then drills quarter inch holes at each of the six marked locations (figure H). "It's a good idea to [add the tuners] before you join the neck to the body," says Dudenbostel, "because it's a lot harder to handle once the body is attached."
A set of bushings is inserted into each newly drilled hole (figure I) and, after masking tape is removed from the fingerboard, Lynn reveals an exquisite neck for his fiftieth custom guitar (figure J). The frets will be installed later. For now, Lynn sets the neck aside as he begins work on finishing the guitar body.
Finish for the Guitar BodyThe body is finished using varnish. Another choice could have been lacquer. But whichever he chooses, Lynn has a golden rule for finishing. "In the case of an instrument," he says, "typically the less finish, the better. The more finish you build up on the surface of the wood, the more you hamper the sound of the instrument; the more trouble it has vibrating. So you want to get by with a minimal finish, but still have a nice-looking finish."Lynn begins the finishing at the spray booth. First he lightly coats the spruce and rosewood with a sealer-coat of shellac. He carefully and evenly coats the guitar starting first with the sides (figure K). Experience is helpful here. No one using a sprayer for the first time should expect a perfect coat. It can take years to develop a spraying style that delivers perfect coats of shellac. When finished with the rosewood sides and back, Lynn sprays an even coat across the spruce top. Once that coat dries he usually applies one more coat of shellac to the body (figure L), then sets the body aside to let it dry overnight.
After sanding the shellac, Lynn begins brushing on the first coat of varnish (figure M). Once that coat is dry, he sands again with 320-grit sandpaper (figure N). A second coat of varnish is applied, and Lynn repeats the process again and again. All those coats of varnish could hurt the guitar's sound. That's why many of his customers ask Lynn to keep the coats to a minimum. "They're afraid of getting too much finish on it," he says, "but I always tell them 'No, it's not how many coats you put on it, it's how many you leave on it.' Ultimately Lynn will brush two or three coats of varnish on the spruce, and four or five coats on the rosewood. Each coat added gets sanded with a finer grit of paper. "Varnish is an acoustically superior finish to lacquer, in my opinion," says Dudenbostel, "It's more work, and it costs more to do it this way, but you end up with a better sounding instrument."
Clogging can occur with finer grits of sandpaper, so another sanding technique is introduced after the first couple of coats. Wet sanding isn't exactly a requirement. Lynn could sand with dry paper, but he would end up using about five times more than necessary. The wet-sanding phase is over when the guitar's finish is smooth and uniform (figures O and P).
In the segment that follows, Lynn finalizes the finish with a French polish, then joins the neck to the body and installs the bridge.
RESOURCES :
Stewart MacDonald's Luthier Supply Shop
Website: www.stewmac.com
Luthier's Mercantile International, Inc.
Website: www.lmii.com
Pioneer Valley Luthier Supply Company
Website: www.pioneervalleyluthier.com
GUESTS :
Lynn Dudenbostel, Luthier
Dudenbostel Stringed Instruments
Knoxville, TN
John Arnold, Luthier
Newport, TN
Ted Davis, Luthier
Loudon, TN
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