Wednesday, January 13, 2016

Fingerboard Oil, ad infinitum

Here’s what I can advise about fingerboard oil. (Spoiler alert: there is no indisputably “best” fingerboard oil!)

What’s the point of fingerboard oil? Given, it’s to coat the fingerboard surface to slow or impede moisture loss or gain. This is desirable because it slows the fingerboard from shrinking or swelling on the guitar. And since we usually chose hard, glassy woods such as ebony as ideal for fingerboards—ebony being notoriously reactive to ambient humidity changes—sealing is important. Literally anything oily: motor oil, Crisco, 3-in-1, lard, will do the job. But they stink. So there are additional criteria.

If sealing was the sole criteria, lacquering the fingerboard surface would be ideal. Lacquer wouldn’t display the problems that oiling presents, as I detail below. But it makes little sense to lacquer a surface meant to be abraded constantly by the fingers and by the strings. Experience shows that lacquered fingerboard surfaces becomes flaked and pitted within a year or two of hard use. So, although many Latin-American luthiers lacquer their fingerboards on their folk instruments, it’s generally considered bad practice. You probably have seen what happens to lacquered maple fingerboards on old Tellies and Strats. Coatings become easily uncoated. The only good thing going for lacquer is that it doesn’t attract and hold dust and crud, like the other alternatives do.

So what’s left? Oil or wax. First, wax. My finishing-chemist friend says that a light coat of any clear furniture wax, like Carnauba, would be ideal. He says that you’ll need to replenish it periodically as it wears off, but new wax actually redissolves the old, and if applied moderately, won’t build up: it’ll always have just one coat of wax, after buffing. And after it’s buffed and dry—and this is a good thing—like lacquer, it doesn’t attract and hold any dust or dirt. So wax has no down side, it seems—just that I haven’t heard of many luthiers waxing their fingerboards, although I’ve heard that some old timers used wax. But I’m not in the habit of using it, myself.

Oil, which is considered a penetrating finish, is far more commonly used than wax. Besides sealing the surface—albeit it, temporarily—the advantage of oil is that it does not flake off or get pitted. But on very hard, tightly-pored fingerboard woods such as rosewood or ebony, very little actually penetrates, so it eventually wears off and needs to be replaced at intervals. This is particularly true in areas of the fingerboard that are played on. But on areas that are not often played on, the stuff just sits there and builds up. 

As far as oils for wood finishing is concerned, here is what my finishing-chemist friend says: there are basically two kinds of oil: drying and non-drying. The non-drying don’t undergo a chemical reaction (i.e., oxidation). The most common non-drying oils are lemon oil, orange oil and mineral oil. These oils have a very slow evaporation rate and remain on the surface in a microscopically thin semi liquid state for days – even weeks – after application. So they’ll wear away where the surface gets used a lot and build up and attract dust and dirt where you don’t play. But many guitarmakers like them, and recommend that their customers periodically (i.e., on every string change) replenish the playing surface with these non-drying oils—and less often, scrub the buildup off with spirits of turpentine and follow with a new coat of their favorite non-drying oil. Some people like to do that because they think they’re coddling their beloved.
Drying oils such as tung oil or linseed oil actually undergo a chemical change as they dry and attempt to bond chemically with the surface. As they become hard through oxidation, they become difficult to remove and over time the accumulation of layers of dried oil forms a shell over the surface. So they build up and they don’t come off, looking rather badly after a long while. So I stay away from them.
Alas, there is no consensus among “experts". My teacher, Michael Gurian, clearly an expert in his field, used his own blend of Cocoanut and Eucalyptus oil. All I could get out of him to justify it was that it smelled nice and always stayed a little oily because they are non-drying, so it would actually lubricate your fingers as you played and your fingers wouldn’t squeak on the wound strings while playing.  He used to supply it commercially, but he doesn’t anymore. My stash of Gurian Fingerboard Oil is long used up, sadly.

Most current commercial fingerboard oil preparations usually say they include something called “lemon oil”. You’d think that it came from lemons. In most cases, you’d be wrong. My finishing-chemist friend revealed to me that “lemon oil” on the market is artificially-lemon-scented-whatever-oil-they’re-trying-to-get-rid-of, drying or non-drying. So you take your chances. REAL lemon-oil preparations are a good candidate, and like most non-drying oils, they will temporarily seal the wood surfaces, making the wood look nice and smell nice. So you wouldn’t be WRONG to use  them—assuming you can confirm that it actually comes from lemons so it’s lemon oil and not “lemon oil”, AND that they doesn’t contain any silicone oil.  Before applying any oil to your fingerboard you have to know that it doesn’t include any silicones or silicone oil of any sort. “Contains no silicones” is what you’re looking for on the label. Silicones are very bad to have on your guitar. So most commercial “furniture polishes” are verboten because typically they do have silicones (i.e. Lemon Pledge and the sort). Silicones “migrate”: they spread from the fingerboard to your fingers and eventually cover the entire guitar—making any future reglueing or finish repairs problematic. My warranty is void if I find any evidence on my guitars of silicone polish or any fingerboard treatment that has the typical slick, silicone look.

Finally, after using up my last jar of Gurian Eucalyptus/cocoanut fingerboard oil, I’ve settled on a commercial preparation that is essentially light mineral oil, thinned out a bit with mineral spirits. Some commercial “lemon oil” preparations are actually lemon-scented mineral oil. Read the label. Look up the company’s website. Ask questions. Finally, Baby oil, which is essentially mineral spirits will serve as an excellent fingerboard oil. If its too thick to handle and apply, thin it out with  a bit of mineral spirits.

Friday, July 17, 2015

Luthier acoustics

A student of mine has become an intimate personal friend. Enrico Schiaffella resides in Rome, Italy, and has become noted as a fine classical builder in his own right. He wrote to me to recount his discomfort at being interviewed on TV, with questions that assumed that he knew just how guitars worked and how they sounded like they do. He wrote: "...but he is not the only who talks about scientific aspect of sound. I cannot bear it: I mean, the luthier is just an artisan—kind of a specialized  carpenter. He is no PhD in physics. How should he know about acoustics? I would not know what to say. These people are just crazy. They make a lot of talking about nothing." I responded,

I thought this was just a stupid American weakness. Your message is proof that it is a universal weakness.

People look at a string. It is silent. They look at a guitar. It is silent. But when the string is moving, beautiful sound is created. It must be magic. It must be science. The builder must know precisely how to make the inert material sing. He must be steeped in great, ancient wisdom. He must be a shaman. Or at least an apprentice shaman. 

So with this illusion, they are excited to ask you to explain the magic. You don't want to deflate their expectations. That would be rude. Besides, if you admit that you are working at the edges of true knowledge, they will think, "wrong guy. Impostor. I should be interviewing a real shaman. Later for you."

But the truth will set you free. You simply refuse to play the game. When someone asks you to answer a "loaded" question like "have you stopped beating your wife?" You can't answer just yes or no, because in either case you are admitting to being a wife-beater. You can only answer. "How did you come to the conclusion that I am beating my wife?" THEN you can respond to that.  

The guitar-making version of a loaded question is , ""Do you build with a thin back so that the whole guitar vibrates, or are you married the modern school where the back is very thick because you don't want it to vibrate? In this case, the soundboard is mainly responsible for the sound generation"

The only answer is "I build the back to the same thickness of the traditional models that I admire." and then, "I am only married to the school of Hernandez y Aguado." and then "where did you hear that the soundboard is mainly responsible for sound generation?" They might then answer, "well I heard it from great guitar builder so-and-so, who affirms that this is true." 

Your response would then be, "did you ask him how he came to that conclusion? I would like to know how he found that out! Did he study acoustics? Did he do double-blind experiments? I hope he didn't just make it up!"  

You may be fearful of being seen as an ignoramus because you aren't sure why your guitars sound so good. But instead, I would look forward to this opportunity to deflate and perhaps end this bullshit-propagating process. All in a polite, non-threatening or insulting way, of course. 

Don't answer his questions directly at first: question the questioner's assumptions. The assumptions that he is trying to make you validate. You simply don't validate the assumptions.  You can reveal that the emperor has no clothes--that there is no Wizard of Oz behind the curtain. The posture of being fascinated by the many mysteries of sound production is not an unattractive stance. You can say that it is these mysteries that keep you fascinated and energized to pursue this ancient craft. But for someone in your position--as a scientist--working in a realm of mystery, you remain skeptical of the many scientific claims made by non-scientists. You tend to trust empirically-derived conclusions, such as: 

  • That soundboard timbers cut in a certain way give a more satisfying response than if they are cut in a different way.
  • That an extremely wide array of soundbox wood choices give satisfying results, not just rosewood.
  • That the closer you can come to the choices and techniques of the great masters of the past, the better the chances that your guitar will sound like the models that we all have come to love and admire.
  • That guitar acoustics is in such a state of infancy, that it can only shine very little light on how the guitar works. But a basic knowledge of acoustics helps dispel the many made-up popular explanations of how it works, such as "the soundbox amplifies the string sound." and, "the back is a sound reflector" or "the soundboard generates all the sound of the guitar." 
  • Until guitar acoustics matures, your only reasonable recourse is to simply look for the answers in the work of the great masters. The closer you can get to their solutions and decisions, the more masterful your guitars will result.  

Does that help?

Abrazos, mi hermano...


Friday, May 8, 2015

Can re-stringing hurt your guitar?

Dear Bill,
I am having what's turning out to be a rather heated debate with a few of my friends on the topic of re-stringing an acoustic guitar. They are saying that you should NEVER take off all the strings at once, but rather change them one at a time. They think that removing all the strings at once is somehow detrimental to the guitar. Having built a few steel-strings from your book, I say "hogwash". Take off all the strings if you want. It won't hurt a thing.

A note from you on this topic would settle it once and for all. 

A "heated debate" about how removing all the strings are "somehow" detrimental to the guitar, huh? Anybody advance any...evidence on their side? I did'nt think so. It must have been battling Beliefs.

The Belief most likely originated from rather good advice for players of all TAILPIECE instruments (violins, cellos, arch-top guitars): if you take all the strings off, the bridge falls off! —and in many instances, the soundpost falls, too. This useful tip apparently jumped at one point from one instrument world to another, starting as sound advice on violins and arch-tops and becoming dopey advice on guitars. The skewed information subsequently got handed down uncritically from teacher to student over the years and thus became generally enshrined as a Belief. By the way there are dozens of similar religiously-held myths among players/teachers/makers—like, never cut the strings. "It damages them" I heard. I should try to list them all some time.

I also love watching proponents "reverse engineering" a justification for a myth! That is, they start with a myth, and then create an elaborate set of highly logical and credible reasons why it must be true. A quintessentially human trait.