The nut is something of an unsung hero on the guitar. Probably named for the German nut [noot] (translating to “slot” or “groove”), the little block between the tuners and the fretboard is integral not only to open-string tone but also to the overall functionality of the instrument. It’s understandable that they’re sometimes overlooked: by weight, the nut accounts for something like .05%-.08% of a guitar. And yet, one of the most common requests for modifications we get here at the Guitar Bar is nut replacements. Clearly, there’s more going on than meets the eye, and there’s a reason we (and the rest of the tone nerds) place so much importance on such a small piece of the instrument.
The nut is one of the only locations on the guitar where the string is always making contact. Differences in material can have a huge impact, as evidenced by the vast array of natural and synthetic options currently available on the market. But among the hunks of plastic, brass, graphite, TUSQ, phenolic, ebony, ivory, etc., there’s only one true king: the humble bone, used on guitars for centuries, dating back even beyond the origins of the instrument as we know it today.
So, why bone? There are essentially three criteria in evaluating whether a material will be well-suited to be a nut:
Lubricity: An overly fancy word for a material’s ability to reduce friction between surfaces in contact. In this case, that’s the friction of the string rubbing against the nut. Friction can greatly impact tuning stability: if the strings are getting stuck while fretting and during bends, not returning to the original degree of tension with ease, it can be very hard to keep the instrument in tune.
Density: The denser a material is, the more efficiently it can transfer the vibrations of a string to the rest of the guitar, typically resulting in a richer, fuller open-string tone. Denser materials also offer improved sustain, absorbing less energy from the string and as such allowing it to vibrate for longer.
Hardness: The overall durability of the nut is largely dictated by hardness, which can also impact the transfer of the string’s vibration to the neck similar to density.
As a material, bone checks all three boxes. All that calcium phosphate makes them plenty dense and hard, particularly the cattle femur and humerus bones most commonly used for nuts. After all, those bones spent a lifetime supporting 1,000+ lbs. of bovine bulk before they ended up installed on your dreadnought. Additionally, as an organic material, bone contains natural fats; these fats act as a lubricant for the strings, reducing friction.
Some folks like the durability and sustain of a notably hard material like brass, and some prefer the engineered predictability and animal friendly nature of synthetic materials like Corian and TUSQ. But despite the development of various alternatives, bone has endured as a popular choice, prized for its rich resonance and natural-sounding warmth.
Enough background - now we can get to the off-white matter at hand. Not all bone is created equal, at least in the state it appears on instruments. We’re here to establish, as definitively as possible, whether or not bleaching a bone nut has a significant impact on the nut’s functionality. Bleaching is typically done for aesthetic purposes: proponents of the technique prefer the uniform whiteness it affords, in contrast to the mottled yellowing and darker coloration of natural bone.
It’s important to note that while the process is called “bleaching,” no actual chlorine bleach is used. Put that Clorox back under the sink - bone quickly becomes brittle and weak if it’s exposed to that particular chemical, which leaches the calcium away from the other chemical components of the material. Typically, hydrogen peroxide is used to whiten nuts, which is much gentler on the bone and has much less impact on structural integrity. There are a variety of other products available, each purporting to clean and whiten without impacting the bone, but peroxide remains the most commonly used. The peroxide acts as an oxidizing agent: when it comes into contact with stains on the bone, it releases oxygen atoms, which in turn break down chromophores (color molecules) into colorless components.
While fans of bleached nuts argue that the process has virtually no effect on the material itself, that isn’t quite true. First, while peroxide doesn’t immediately break down the fats in the bone, it does induce a process called lipid peroxidation, which eventually leads to the degradation of those fatty acids. Additionally, peroxide can degrade the collagen matrix of the bone, which does impact the overall structural integrity of the material. It doesn’t make the bone brittle and fragile the same way bleach does, but it can lower the density of the bone, which in turn affects the overall efficacy of the vibrational transfer and can diminish longevity.
There are other methods to bleach bone: some prefer to use plain dish soap, claiming it can clean the bone without altering the chemical structure at all, but it does still strip away the natural oils. Think Dawn ads with greased-up birds.
Some folks use nothing but sunlight, letting the bones sit out like skulls in a Georgia O’Keefe painting. Once again, however, there are potential pitfalls: the heat and intense UV radiation can lead to warping, shrinkage, and cracking, and overall fragility can increase significantly if the bone is exposed for too long.
Last but not least, some claim that fossilized bone - or ivory, for that matter - is a best-of-both-worlds option: because the bone effectively turns to stone during the fossilization process, it’s about as hard and dense as you could want. Fossilization significantly reduces porousness and makes the material very consistent, so the differences between, say, a nut cut from the center of a bone (more porous) and the exterior of a bone (less porous) disappear. Additionally, some allege that fossilization removes imperfections and flaws from the bone, so even though natural fats are lost through the process, the resulting material still experiences a reduction in friction. Unfortunately, there’s not really enough research to support or refute that claim, but it’s unlikely that any overall reduction is superior to the presence of naturally lubricating fat.
There’s only one certainty: if you want to get the most out of your bone nut, and be confident it’s as dense and well-lubricated (please, save the jokes) as possible, you’re probably best off leaving it au naturel. While that uniform whiteness might looks slightly cleaner up close, the cost of the look may be an impact on performance (and resultant tone). And the day we stop caring about performance and tone is the day we lose our carrying cards as licensed guitar nerds.
If you’re looking to upgrade your nut, swing by our Service department Tuesday through Saturday, 10:30 to 6:30 (or email service@mmguitarbar.com) - you’ll be shocked just how big of a difference it can make.
-S. J. Feehan
Great writing. Superb.