Grenadilla Wood, Environmental Effects, and Organic Bore Oil
Copyright © 1991, 2001 by Larry R. Naylor, all rights reserved
Click here to printClose window Return to Naylor's Custom Wind Repair

Eventually many of us will face the reality of deterioration of grenadilla and other wooden instruments. Some of us can use our favorite instrument for many years before its performance becomes unacceptable, while others have to replace their instruments more frequently. Some of us actually replace instruments every year or two!

Obvious indications of deterioration include cracks and raised grain in the bore. Less obvious problems include a deteriorating scale, increasing intonation problems, and declining resonance. Tuning pitch may drop below A-440 tuning. Often, one declares an instrument "played out" or "blown out" when these problems become extreme enough.

What can a performer do to avoid or even reverse this deterioration? I would like to share my attempts to answer this question. I will draw upon over 28 years of empirical data I have accumulated involving the use and effects of organic vegetable oils on grenadilla and rosewood.

Played-Out, Blown-Out—The Instrument has lost Its Voice

For some time now, many players have referred to instruments becoming "played-out" or "blown-out". One could also say that the instrument simply has lost its voice. This condition is common in instruments that have changed dimensionally over time, especially if they had received little preventive maintenance. Typically the scale may become uneven and out of tune. In addition, the tuning pitch will usually go flat. Ultimately, an instrument is "blown-out" when its scale and tuning pitch have changed to the point where the instrument no longer meets the artistic demands  of the musician. Since a player perceives an instrument's "good" or "acceptable" playing qualities according to his ability, an amateur musician may like his wooden instrument while a professional would reject it. We will revisit this subject after the presentation of several basic concepts.

In the following document, I provide the reader with information necessary to make rational decisions about the care and maintenance of grenadilla and rosewood instruments. One must realize that a "blown-out" condition of an instrument is reversible as long as it has not been re-bored. With careful maintenance in the first place, one can avoid the possible pitfalls of deteriorating wood and a changing voice.

In earlier versions of this article, I omitted enough information to confuse the issues and, for a while, anomalous measurements were misleading. It didn't take long to realize that it is almost impossible to take consistent, reliable, precise measurements of wood that otherwise can change dimensions daily by one to two thousandths of an inch. However, to be meaningful, most measurements need   to have an accuracy of less than one thousandth of an inch, thus precise measurements proved to be generally impossible. It occurred to me that what is important is the incredibly complex array of dimensional ratios that describe the relationships of tone holes to one another and to the instrument's bore.

I have now included more information concerning, for example, the differences between heart    wood and non-heartwood instruments and how each can react to its local environment. This  section was added because many people apparently erroneously assume that all instruments are made of heartwood and this assumption interferes with their ability to understand the dynamics of the interaction of wood, moisture, and organic oils. All new information is partially a result of additional experiments and observations made during the past eleven years. Because of this additional information, this current document supersedes all older articles and handouts I have written.

Cutting Patterns and Billets

Let us explore two basic approaches to ripping a log into billets. After cutting, billets for soprano instruments typically measure roughly 2 by 2 inches (or less) by the needed length. After sorting for quality, they are aged or seasoned. At some point in the seasoning process, manufacturers may bore an undersized, rough hole through the center of the billets and age them further. The time used for aging can vary from one manufacturer to another. Some may season billets for five to ten years while others may season ten to fifteen years. Contrary to careful seasoning, one manufacturer admitted that they warehouse wood for up to six months before turning billets into oboes. Their instruments are typically unstable in dry climates and they are very prone to cracking.

Please note that figures are not drawn to scale. Figure 1 represents a cross section of an irregular log ripped into nine billets; the heavy vertical and horizontal lines represent basic saw cuts in the log. In this example, the good or usable wood in this log would have to be greater than six inches in diameter. This cutting pattern would produce up to eight usable non-heartwood billets and one heartwood billet. It does not matter how large a log's diameter is because only one heartwood billet can be produced per unit length of log when the cutting pattern is similar to Figure 1.

Figure 2 represents a cross section of a quartered log. Note that the good wood in this log would have to be greater than four inches in diameter. This cutting pattern would produce four non-heartwood billets only.

Figures 3 and 4 represent cross sections of the two types of billets—non-heartwood and heart  wood. Note that the annular rings or grain in the heartwood example form more-or-less concentric rings while the grain in non-heartwood billets runs from top to bottom. Oboes, English horns, piccolos, flutes, and very few clarinet models are made from heartwood billets. For example, Buffet Crampon currently uses heartwood only in their Prestige model clarinet while, according to a Wurlitzer technician, H. Wurlitzer in Germany currently uses only non-heartwood in all their clarinets.

It should be obvious that most grenadilla wood billets are non-heartwood. However, a manufacturer's choice of whether to use heartwood or not does not reflect a choice between wood of greater or lesser value. Wood used to manufacture world-class instruments represents the best available on the market and the two types of billets are simply different: they have different physical characteristics and they react to the environment, saliva, and age in slightly different ways.

Two Classes of Dimensional Change

Two classes of dimensional change occur in wooden instruments. The first type, long-term change, occurs over a long time, typically months to years. Changes in the wood are a function of its grain structure, levels of internal stress, seasoning procedures, and local environment. Since each piece of wood is theoretically unique and non-uniform (heterogeneous), each will respond to its local environment in slightly different ways. There are, however, similar patterns of change that most instruments follow. Wood will usually change dimensionally as it responds to its local environment, saliva damage, maintenance procedures (or a lack thereof), and frequency of playing. These long-term dimensional changes may eventually render the instrument's voice unacceptable to a serious musician.

Playing the instrument will generate the second class of dimensional change, representing short-term change. Initially, the instrument will play flat when cold, but as the bore warms and expands, the tuning pitch will rise as the bore becomes slightly larger. When one swabs and puts an instrument in its case, its bore will contract as it cools and dries. I often refer to short-term expansion and contraction as "breathing". Wood will always respond dimensionally to changes in temperature and its moisture content.

However, proper maintenance procedures will minimize the extent of dimensional changes caused by moisture content. The two classes of dimensional change apply to both heartwood and non-heartwood instruments. However, the two types of wood react in different ways as the wood changes dimensionally. In general, a heartwood bore will remain approximately round during expansion and contraction, while a non-heartwood bore will be typically round to oval in shape. Theoretically, an instrument's bore will be at its roundest the moment a finishing reamer leaves it during manufacture. The shape of tone holes and post holes can also change. Tone and post hole dimensions do remain slightly more stable in heartwood instruments.

Expansion and Contraction

The instrument's bore and outside diameter usually become smaller as heartwood shrinks. Conversely, when heartwood expands, the bore and outer diameter become larger. These dimensional changes are not necessarily uniform, but the bore and outer circumference will remain essentially round.

Expansion and contraction of non-heartwood are somewhat more complex. Figures 5 A, B, and C represent cross sections of non-heartwood clarinets. Here, I exaggerated examples of dimensional change. Note the spacing of the grain (annular rings) in the three examples. This is an attempt to show how the wood moves and in which direction as it changes dimensionally. Note that orientation of the grain is vertical and the top of each figure represents the top of the instrument. With clarinets, manufacturers, for example, apparently prefer to cut the upper joint stack tone holes into the grain edge. Occasionally, I find wood grain that runs diagonally or horizontally relative to the stack tone holes.

Figure 5B represents a clarinet cross-section at the time of manufacture. The bore and outside body will theoretically be round and the wall thickness will be uniform. From this initial condition, the wood will either expand or contract as a function of many factors including the local environment.

Figure 5A represents the change in shape of a clarinet cross-section caused by dryness and saliva damage as these factors interact with the wood's internal stresses. This change in shape also occurs to a lesser extent in humid areas, where shrinkage is more a consequence of saliva damage and internal stress rather than dryness. Note the closeness of the grain in this example. One can see that the wood has collapsed into itself in the horizontal direction. The instrument walls are thickest at the top and bottom and thinnest at each side. We also see that the major diameter is vertical and the minor diameter is horizontal. These dimensional changes will also affect the shape of tone holes and post holes depending on their orientation relative to the direction of the wood's grain. Even though it is not obvious from the drawing, the bore in this example is usually smaller than the as-manufactured example. This will tend to cause the instrument to play flat in pitch.

Figure 5C represents a cross section of a clarinet whose moisture content is greater than the as-manufactured condition. Note the width of the grain and how it depicts the expansion of the walls at the sides. Also, note that the side walls are thicker than the walls at the top and bottom. We also see that the major diameter is horizontal while the minor diameter is vertical. The bore in this example would tend to be slightly larger than the as-manufactured example. The pitch of instruments in humid areas should theoretically go slightly sharp. However, empirical data indicate that saliva damage and age may not only cancel a sharper tuning pitch, but may eventually cause the pitch to fall unacceptably flat. The shape of tone and post holes may change as a function of their orientation to the wood's grain.

In all three examples, we note that the wall thickness at the top and bottom is essentially the same. This thickness does change but it is so slight that it is not measurable directly. The length of an instrument body may also change in both heartwood and non-heartwood instruments. With new instruments, I have noted how much material I remove, on average, when refitting binding keys running along the long axis. The approximate percentage shrinkage of the wood that causes these keys to bind is 0.03 to 0.04 %. I assume that the amount of shrinkage along the long axis is essentially the same percentage change as the shrinkage or expansion of the wall's thickness at the top and bottom of the three examples in figures 5 A, B, and C.

We need to note that the amount of change in the dry condition example is greater than that in the wet condition. In addition, the amount of dimensional change in the three examples may be so slight that it is not directly measurable. However, any change in the pitch and scale of an instrument would indicate that dimensional change has occurred. Oval clarinet bores are very noticeable and usual in a dry climate while instruments shipped to me from more humid areas do not show, on average, the same degree of dimensional change.

Stress Relief and Binding Keys

The relief of internal stresses in wood, during and after manufacture, accounts for an important factor that affects how wood changes dimensionally. For example, one can joint and plane a hard maple board so that it is very straight in all directions. The board is under stress from shrinking during seasoning and drying, but stable and straight as a single piece. If one then rips one-quarter to one-half inch thick pieces from this board, each piece will usually warp and wind from the relief of internal stresses. The straight board one started with will also begin to warp and wind.

Careful long term seasoning maximizes the quality and stability of billets. Each, however, will develop its own pattern of internal stresses that result from the drying process. Long term seasoning is an attempt to reduce initial internal stresses in billets, but the stresses equilibrate  rather than disappear. Like the maple board example, when machining a billet into an instrument, internal stresses may re-orient within the wood, resulting in increasing dimensional changes until the piece equilibrates. Binding keys on a new instrument indicate that the wood is continuing the process of stress relief as it adapts to its current local environment and that the wood is changing dimensionally.

Stress relieving occurs in both non-heartwood and heartwood instruments. As an experiment, an oboe manufacturer told me that they cut a tone hole in an instrument body and left the machining set-up untouched over night. When they passed the cutter through the same tone hole the next day, they found that they removed more wood. Since the room was climate controlled 24 hours a day, the only explanation for the removal of additional wood would be stress relief occurring within the instrument body overnight; its shape was slightly changing because of the machining process.

New and used instruments shipped to, for example, a dry environment such as Denver, will immediately change dimensionally. Keys will typically bind or become too loose and socket and   bell rings usually become loose. These dimensional changes are a result of the interaction bet   ween the wood's changing moisture content and internal stresses. These changes are typical with both heartwood and non-heartwood instruments. Dimensional changes causing binding keys on new clarinets are not as frequently found as with new oboes because clarinet manufacturers fit keys less precisely. I can fit keys very tightly on clarinets only when the wood has been immersion processed first. Tightly fitted keys on an untreated clarinet body may eventually bind as the instrument undergoes short and long term dimensional changes.

Let us use world-class oboes to demonstrate how keys can bind as a function of wood movement. The highest quality oboes have keys fitted very precisely to their hinge and pivot screws and key posts. Further, hinge screws are usually a snug fit in their respective key post holes. Any excess key movement would be virtually undetectable; if keys were much tighter, they would not move. These examples also apply to clarinets, but the degree of post movement will depend upon their relative orientation to the grain.

Figure 6 represents a cross section of an oboe body. Notice the approximately concentric annular rings or grain of the heartwood. When the wood shrinks, its outside diameter gets smaller and posts located perpendicular to the long axis will lean or move closer together. The associated key will no longer fit between the posts and it will bind. If shrinkage is great enough, the screw holes in the posts will no longer align. If the hinge screw is a snug fit in the post hole, and if the screw threads lock into the inner threaded post, the post mis-alignment often causes the screw to curve or warp down slightly, thus causing the key hinge tube to also bind on the warped hinge screw. Both causes for key binding typically occur on the D# and C# keys on the oboe's lower joint. If a key still binds after fitting the hinge tube between the posts, you would know that binding caused by post misalignment is occurring when, if you back the screw out slightly, the key then moves freely. Because springs are very light, these keys can tolerate little friction.

In a wet condition, posts that are perpendicular to the long axis will move further apart as the wood's diameter expands and the hinge screw may arch up slightly. The dimensional changes and post misalignments represented by Figure 6 could be problematic for traveling professional musicians playing oboes, and to a lesser extent, clarinets.

There are two additional interpretations of figure 6. It can also represent the effects of short-term dimensional change; as the instrument warms when first played, the wood will expand because of an increase in temperature and moisture content. I have repaired many instruments where binding keys did not become evident until the instrument was warmed from playing.

Long-term dimensional change represents the second interpretation. After one plays an instrument for several years, dimensional changes in the wood and key wear may render the key system compromised. I typically correct this condition by immersion processing the wood and refitting all keys.


We must realize that wood will change dimensionally in response to its local environment. Any changes in its moisture content and temperature will always have dimensional effects, however subtle. Further, wood breathes as it adjusts to the frequency of playing and the care taken in swabbing the bore. The instrument will also respond to saliva over time; the more caustic the saliva, the greater the effects of deterioration.

Internal Stress, Short and Long Term Dimensional Changes, and Cracks

The wood in all instruments is under some degree of generalized stress: The greater the stress, the less elastic the whole piece will be. One could say that a piece of wood is most stable or unstressed when it is green. As wood dries, its fibers collapse or shrink into themselves: Heartwood billets will shrink towards their centers, while non-heartwood ones will shrink more in one direction, as in Figure 5A. Short-term dimensional changes result from changes in moisture content and temperature as one plays the instrument. Long-term dimensional changes occur over a period of months to years and they represent the accumulated effects of the local environment, including saliva damage. Saliva may affect the condition or health of the wood fibers at the bore and contribute to internal stress in the whole piece. The amount of internal stress in wood is a consequence of the interaction of short and long-term dimensional changes, moisture content, the rate of temperature change, saliva damage, and age. The initial quality of the wood also enters into the formula.

The presence of burls and uneven grain will contribute to localized stress, as will a too tight key post or register insert. A burl near a tone hole may even cause that tone hole to change its shape more than other tone holes in the same piece of wood. Uneven grain, including burls, tight posts and register inserts may represent a point of origin for a future crack.

Cracks occur when generalized and localized stresses within the wood overcome the wood's elasticity at any given point. A rapid change in moisture content and temperature will further stress the wood and increase its chances of cracking.

It seems that there are four classes of cracks. The most common occurs when one plays a cold instrument. The sudden rush of hot, moisture saturated air causes the wood at the bore to expand more rapidly than the wood on the outside of the instrument. If this expansion generates pressure great enough to overcome the elasticity of the wood, one or more cracks will occur. In heartwood, cracks will follow a path of least resistance through post holes, tone holes, register inserts, and areas of high localized stress. In non-heartwood, cracks will occur at the edge of the grain as in the top and bottom areas in figures 5A, B and C. These cracks will also follow a path of least resistance. I have never witnessed cracks occurring perpendicular to the grain in non-heartwood, as in Figures 5A, B, and C at the sides of the drawing. Heartwood can potentially crack at any point around the instrument's circumference. However, this is not the case with non-heartwood.

The second class of cracks occurs when a warm instrument quickly cools on its outside surfaces. The wood on the outside of the instrument simply contracts faster than the inside. This can happen when someone opens an outside door or window near the performance area. Cracking may also occur when someone puts a very warm instrument in an un-insulated case and immediately takes it out-of-doors on a cold day.

The third class of cracks involves a series of parallel cracks in one or more areas of the instrument body. They are usually smaller than cracks caused by rapid temperature and moisture changes and seem to be mostly a result of long term deterioration that generates areas of high localized stress in the wood. Examples of this class of cracking occur in instruments that have been in continual use for many years, but with no maintenance using organic vegetable oils. I usually only see this cracking pattern in heartwood instruments.

The fourth class of "cracks" occurs only rarely and has only been witnessed in non-heartwood. You can find an example of this type at the end of this article under the heading Track Record. This condition does not really start out as a crack at all and it results from extreme saliva damage over time where no organic oil was used to protect the bore. With no protection, strong saliva usually causes grain in the bore to raise. Raised grain is especially common in dry areas, but it can be found in instruments from any climate. If strong saliva continues to work on the bore, the raised grain will eventually form deep "V" shaped recesses between the grain (annular rings). Please realize that the "cracks" start in the bore and slowly progress to the outside of the instrument. Once the wood becomes thin enough from the bottom of the recess to the outside of the body, any slight stress can cause the "valley" to crack through to the surface of the instrument. In the example given under Track Record, the act of vigorously playing the clarinet, after being in storage for two years with no maintenance, generated too much stress in the wood and the "V" shaped groves erupted into the base of post and key guide holes. The instrument leaked from under key posts and key guides!

I have observed that any detrimental changes in a world-class instrument, especially after its first year of use, usually indicate that something is wrong with the care and maintenance procedures used. Careless break-in and poor preventive maintenance may contribute to cracks during the instrument's first year of use. However, cracks in a new instrument may also result from an otherwise highly stressed piece of wood. Occasionally an instrument may crack in spite of fine, thoughtful care, but this is infrequent. Because of lower wood quality, intermediate instruments require even greater care to avoid cracking problems. We will soon see that most detrimental changes that occur in wooden instruments are both preventable and even reversible.

Brittle wood and Elasticity

Wood shrinks as it ages and this shrinkage generates generalized internal stresses. When combining these stresses with saliva damage, the wood becomes more brittle. As wood becomes more brittle, it looses elasticity.

Wood's lower moisture content, caused by a dry climate, usually contributes to the brittleness of wood and, therefore, the lowering of its modulus of elasticity. The incidence of dimensional change is also most noticeable during dry seasons in otherwise humid areas. When wood becomes more brittle, the incidence of cracking, binding keys, loose socket rings, and chipped tone holes increases. Bore shrinkage and oval bores are often measurable. In addition, the tuning pitch of the instrument may go flat (see figure 5A). Clarinetists compensate for these bore changes by using shorter barrels and oboists modify their reeds. Without the periodic use of organic vegetable bore oils, deterioration resulting from dimensional changes and brittleness, aggravated by saliva damage, may become severe enough to render the instrument un-fixable.

Humid climates are much more friendly to wooden instruments. However, extreme humidity can generate additional problems, including mildew damage and swollen tenons that are too large for their respective sockets. Dimensional changes and brittle wood are usually less severe in humid climates and changes in dimensions are often so slight that they are not measurable. However, I occasionally receive an instrument from a humid climate that shows the same kind of deterioration that occurs in a dry climate. I assume that this deterioration is caused primarily by saliva damage and a lack of good maintenance practices.

Over-all Tuning Pitch Changes

If an instrument's tuning pitch changes, it will usually go flat. This applies to both heartwood and non-heartwood instruments in any climate. The worst cases I have come across involved world-class instruments whose pitch had become flat by 25 to 35 cents. These extreme pitch changes occurred in soprano and bass clarinets, oboes, and English horns from both dry and humid climates. A change in tuning pitch indicates that the bore and tone hole dimensions have changed. All the above instruments were immersion processed and their pitch returned to A440. Clarinetists usually return to a standard length barrel on their reconditioned instruments and oboists have to return to making ‘standard' reeds.

For some time now, I have received reports of instruments that eventually "blow" sharp. Now that I know what questions to ask new customers, I am finding that these instruments, clarinets and oboes, come from both humid and dry climates. However, the incidence of sharp blowing instruments seems to be much lower than flat blowing ones. Because of the dynamics involved with immersion processing, I have found that this sharp tuning condition is also reversible. For example, I recently immersion processed and rebuilt a clarinet from San Diego. The client had to use a 67-millimeter barrel pulled one to two mm to play A-440. She indicated that her instrument tended to play at least 15 cents sharp. After repairs were complete, she reported that she could now use a standard 66mm barrel pulled one mm to play A-440. I am currently working to understand why some instruments blow sharp while the majority blow flat.

Blown-out, Played-out Revisited

I have received copies of Web discussions, involving whether grenadilla instruments can become blown-out, from customers and repair technicians from around the country. Since I have been restoring instruments in this condition for many years, I assumed that most musicians were familiar with this problem. Apparently, this is not the case. Identifying slowly accumulating problems with one's instrument can be problematic because most experienced musicians can readily accommodate to, or compensate for, these changes—up to a point. Some musicians are not as sensitive to idiosyncrasies in their instruments; they tend to "drive" an instrument rather than play it. I suspect that some musicians may have only experienced instruments in a relatively compromised condition, thus they do not perceive performance problems on their current instrument; they are unaware how good an instrument can be. For example, a comment I frequently hear from first time clients is, "I didn't know my clarinet (oboe, English horn) could play like this!

Performance Indicators

Let us investigate the performance indicators of a blown-out condition. To answer a question from a web discussion group, this condition does not occur in plastic instruments or metal flutes, metal clarinets and saxophones. Metal and plastic instruments can become worn-out, but not blown-out.

Discussing sound using words is a real problem. I refer to this difficulty as the "Chocolate Problem"; it is impossible to tell people what chocolate tastes like, they have to experience it for themselves, but let us try. A blown-out condition may include one or more indicators. We have already discussed tuning pitch changes, but another involves an uneven scale. By this, I mean that some notes may pop-out when playing while others may be relatively too soft. Again, an amateur may not notice this condition while others would. The instrument's scale and registers may become out-of-tune. On one model of clarinet, for example, the chalumeau register typically becomes quite sharp relative to the second and third registers.

Another indicator is a lack of resonance. One must be careful here because leaks, poor reeds and mouthpieces, and a poor embouchure can cause poor resonance and response. Assuming an instrument is in very good mechanical condition and its equipment is in good order, but it plays as if it is lifeless and lacks richness in timbre, then its resonance is compromised. One can also refer to a lack of resonance as a "dead sound" where the timbre is consistently thin and lifeless. I have heard people say that dead instruments play as if made of concrete. On the other hand, a highly resonant instrument would have a rich, ringing quality in its timbre; you can both hear and feel the liveliness and resonance in your hands, embouchure, and chest.

Poor response and a lack of resonance are factors that usually link. A condition where an instrument hesitates or refuses to play interval and octave leaps indicates that dimensional changes affecting its basic acoustics have occurred. Frequently, I meet with first-time clients who have accommodated to an instrument that exhibits poor response and resonance; to play it requires the musician to over-power its shortcomings or flaws. One could say that instruments in this condition play like "driving a Mac truck". Eventually, the player will reach his limit of accommodation and compensation when performance problems become great enough. Ultimately, a fine instrument is a joy to play while a blown-out instrument is a chore.

Physical indicators of Deterioration

Many physical indicators demonstrate deterioration in wood. For example, the color of healthy grenadilla wood is a deep brown to almost black. I have witnessed many cases where the wood in the sockets, bore and tenons of barrels and upper joints on clarinets had been bleached almost white by saliva! Short of this extreme, the wood, over time, will become lighter in color. Saliva damage usually causes raised grain in the bore; this effect is common in dry areas where the swing of moisture content in the wood is extreme. One of the worst examples I have seen of raised grain was on a clarinet where the player used a fluffy swab that you leave in the bore. The instrument was only one or two years old, yet the bore condition indicated that the instrument was much older. Besides ruining wooden bores, these swabs will also seriously compromise pad life on any woodwind.

I should note that in the past some manufacturers painted their world-class professional instruments black. This is often the case with intermediate quality instruments where paint hides filled defects in the wood. Paint would also hide the wood's current condition.

Loose socket rings and bell rings are other physical indicators of deterioration as is a compromised key fit. Another indicator is an exceptionally loose center joint that fails to hold the upper and lower joints straight. Tenon corks only function to provide a friction fit of the joint. Shrunken tenon shoulders (undersized) and sockets (oversized) determine the amount of lateral movement possible at the center joint. Technicians often mask this looseness by fitting tight tenon corks. There are other, more expensive remedies, but the easiest and least expensive is the periodic use of an organic vegetable bore oil to keep the wood from shrinking.

Cracking problems indicate brittle, stressed wood and often, poor care and maintenance procedures. If your instrument cracks, it is trying to tell you something. Brittle wood can also lead to tone hole chipping problems. An observant repair technician would have to alert you to this problem, unless you are capable of disassembling your own instrument. Chipped tone holes obviously lead to a leaky instrument. If the chips are small, the tone hole may be re-faced. If they are large, tone hole inserts are indicated.

A leaking instrument or an instrument with intermittent playing problems can also be a result of short term dimensional changes that compromise pad to tone hole seal. In this case, the tone holes are changing their shape just enough to disallow clean, crisp, light, tone hole seats or creases in the pads. The keys may also slightly shift their position as the instrument "breathes." Often instruments leak even though the pads appear in good condition and seem to seal evenly with a feeler test, yet the instrument is not as tight as it should be using a vacuum test. If an instrument plays poorly at first but improves as it warms or vice versa, suspect unstable pad seal and binding or moving keys.

The last example of deterioration involves warped bodies where the bore is not straight. This condition is most noticeable with the upper joints of oboes and English horns. I cannot recall ever seeing a warped body made of non-heartwood.

Solutions-Stabilizing Grenadilla and Rosewood

I find the amount of detail used in this presentation unfortunate, but necessary. I want my clients to understand why their instruments behave as they do. With understanding, we are able to better protect our investment while enhancing our performance potential.

When I first moved from Massachusetts to Denver Colorado, I immediately noticed changes in my personal instruments, especially my clarinet. Developing methods of pad installation to increase their stability in a dry climate came quickly. Many experiments and much research occurred before finding a method of stabilizing grenadilla and rosewood. This article represents additional refinements in techniques, methods, and observations I have made during the last ten years along with data accumulated since 1973. A descriptive chronology of my work can be found in the article, Life Everlasting for a Good Clarinet. This article was used as a handout for a clinic I presented at ICA's ClarinetFest 1997 in Lubbock, Texas. An addendum offers a very important example presented verbally during the clinic.

Because the history of my research is covered in other articles on this site, I will only give a brief summary of basic factors I initially discovered. I researched articles that addressed the question of using bore oils. I found that the authors did not address the effects of moisture and one's local environment on wooden instruments. They also consistently avoided identifying the type of bore oil to which they referred.

One must realize that the term "bore oil" is generic; anything one chooses to put in the bore of an instrument can be called a "bore oil". One must also realize that there are two basic types of bore oil: petroleum or synthetic based and organic vegetable based. The above authors failed to make a distinction between these two types. I have found that the only type of bore oil that protects and restores grenadilla and rosewood is a blend of certain organic vegetable oils. They are compatible with wooden instruments while petroleum and synthetic based oils are not. Vegetable oils are absorbed by and interact with wood fibers, while petroleum oils are not absorbed by the wood and do not interact with wood fibers. Therefore, I would never suggest that my customers use petroleum oils; they do not work and they may actually cause problems. I also suggest the use of organic based cork greases; cork readily absorbs this grease and it keeps tenon corks supple and healthy.

Immersion Processing and Hand Oiling Compared

Immersion processing allows me to reverse years of wood damage in about four weeks. It stress relieves wood while generating greater fiber resiliency. It also strongly tends to restore the instrument's original scale and tuning pitch. It begins the healing process of a rough, deteriorated bore, and initiates the process of correcting a loose tenon to socket fit. After immersion processing, there is a three to four week break-in period where the instrument becomes very stable dimensionally. This stability allows, for example, the player to travel to different climate zones without suffering the typical performance problems that result from dimensional change. I consistently receive reports from clients that state that the scales of their instruments "lock in" during the break-in process. In addition, the vast majority of players report a noticeable increase in their instrument's resonance. I typically find that even new instruments become more resonant. Additional improvements are well documented in Life Everlasting for a Good Clarinet.

Immersion processing first involves preparing the wood by removing any petroleum products from the instrument body, including key oil and petroleum based oil and cork grease. The instruments are then immersed in a tank containing a specific blend of organic oils. Depending on the condition of the wood, the actual immersion may last from four or more days. After immersion, the instruments are drip-dried and the condition of the wood is monitored for about three weeks. Once the wood is ready, the instrument is mechanically rebuilt. This includes cleaning and refitting all keys and adding new key and tenon corks and pads.

This processing has several advantages over hand oiling. First, physical and playing quality changes that have occurred over the life of the instrument usually are reversed in about four weeks, while these results from hand oiling are often not noticed for about one year. Second, all surfaces of the wood are treated uniformly, thus avoiding uneven absorption of oil. Third, the immersion oil, formulated specifically for immersion processing, produces superior results when compared to hand oiling with Naylor's organic bore oil formula. The organic bore oil formula was designed primarily for periodic maintenance, but its results are second only to immersion processing.

If one's instrument is showing signs of a "blown out" condition, if the wood is bleached, if the bore has become rough or grainy, if keys bind or are too loose, and if the instrument plays inconsistently, then the instrument really needs immersion processing.

Hand oiling instruments is the approach I used for years before developing immersion processing. The wood will look better after hand oiling and the oil will immediately begin to protect the bore. Hand oiling requires that the player be consistent with and understand oiling procedures. Oiling once or twice a year is not going to accomplish much.

The type of oil to use is extremely important, but the method of applying the oil is just as important. Pull-through swabs and worsted swabs on a wire handle do not work well because one has little control of where the oil is applied and how much is used. Usually, these swabs force oil into tone holes and register vents and they fail to oil the bore between the register and thumb tubes on clarinets. Using these swabs on an oboe or English horn would not be a good idea. Feathers do not work well either because they tend to disintegrate after the first use, leaving pieces of feather in tone holes. In addition, worsted and pull-through swabs will eventually become a gummy mess and a hazard to use in an instrument.

It is for these reasons that I manufacture oiling rods for clarinets, oboes, and English horns. They are tapered brass rods that use a small, replaceable woven cotton tip. With these rods, one can lightly paint the bore of instruments while controlling both where oil is applied and how much is used. Customers who carefully follow oiling procedures do not have problems of over oiling or oil fouled tone holes.

I might point out that an "oil saturated" instrument does not contain a large amount of oil within the wood fibers. Oil does not fill the voids within the fiber structure. Rather, organic oil will locate on the surfaces of wood fibers, as a thin film, within the walls of the instrument. Thus, the quantity of oil the wood contains is slight. For example, kiln dried and seasoned wood initially contains very little moisture, typically 4%. If you could collect all the moisture from a piece of seasoned wood, you would find that the amount of moisture is surprisingly small. If you could collect all the organic oil in a piece of "oil saturated" grenadilla wood, you would find that the quantity of oil is also surprisingly small. Thus, the quantity of oil needed within the instrument's body to protect it is small, but it needs periodic renewal through hand oiling maintenance.

I have immersion processed new world-class instruments, some of which were used in paired comparison tests for an experienced audience. In all cases, the audience preferred the timbre, response, and resonance of the immersed instruments as compared to new, non-immersed ones of the same brand. See the write-up for the clinic, Clarinets and Concepts, presented in Denver and Milwaukee for NAPBIRT conventions.

I typically provide care and maintenance handouts, including organic bore oiling procedures with instruments I repair. Orders for bore oil and oiling rods include instructions for their use.

Track Record

I wish that I had kept records of the number of instruments I have hand oiled and immersion processed since 1973. The hundreds of instruments include Eb, Bb, and A soprano clarinets, alto, bass, and contra bass clarinets, Basset horns, oboes, English horns, piccolos, and flutes. I have also restored many historic clarinets and wooden flutes. I usually enjoy long-term relationships with my clients, thus allowing me to receive feedback from them over many years. I also work on their instruments annually and have the opportunity to monitor instrument durability over many years. I have found that if clients take good care of their instruments and correctly perform periodic bore oiling using my organic oil, cracking is a very rare event. Their instruments are typically quite stable rather than becoming "blown out". Out of all the instruments I have processed, I have had several anomalies.

I immersion processed a student line American made oboe produced in 1945. The instrument had some nasty cracks and its wood was so dry and brittle that it was difficult installing crack pins. Surprisingly, its wood was impervious to both organic and inorganic cleaning solvents and organic oil. I talked with the manufacturer and they had no explanation as to the cause of this condition. Obviously, the instrument was not salvageable because there was no way of keeping it from cracking further.

During the earliest days of immersion processing, I restored a very old Buffet clarinet that featured a top mounted register vent with a wrap around register key. When I first saw it, it looked more like a lamp than a musical instrument. I was curious about what immersion processing would accomplish with this old instrument so I used it as a "put up or shut up" example using my new (and developing) organic oil process. After all work was completed, I was surprised at how well the clarinet played. It quickly sold and the young owner performed well with it. However, six years later I learned that the owner had taken poor care of the instrument and, after more than seventy years of its crack-free existence, the owner managed to crack the barrel.

Several years later I immersion processed an American made, intermediate line oboe that was about thirty years old and owned by the public schools. The instrument was given very poor care over the years and it had received minimal maintenance. Once all work was completed, I gave the current user instructions on its care and maintenance. About six months later, the oboe cracked through the triller tone holes and into the left hand stack. The crack appeared to be typical of oboes that either warm too quickly or cool too rapidly. The cracks look the same in both cases. One thing I did notice was that the player had allowed "stuff" to build-up in the bore. This build-up was not excess organic bore oil because typical organic oil solvents could not remove it.

I perform immersion processing for several repair technicians around the country. Their third party reports have been consistently positive except for one instance. The instrument was a world-class clarinet that was shipped from Nevada to San Francisco, then to Denver for immersion processing, back to San Francisco for all finishing work and then shipped to Nevada. The clarinet cracked within one year. The repair technician and I both agreed that the crack appeared to either result from a too rapid warm-up or cool down. The four dramatic climate changes the instrument went through may have been a factor. When an immersion-processed instrument is shipped from my dry area to a more humid one (San Francisco), the instrument may sweat some oil for several days as the wood absorbs moisture and acclimates. If the instrument is then shipped to a dry area again (Nevada), the wood will loose moisture and need hand oiling to replace the oil lost in San Francisco. The repair technician and I have no way of knowing if the player performed this necessary maintenance in a timely fashion.

The following represents a problem I occasionally see. I immersed and rebuilt Alan's professional clarinet about ten years ago. He has been a professional clarinetist for most of his life and this clarinet had been his only instrument. Before the immersion, the clarinet showed extreme saliva damage to the bore, which appeared to have two large "cracks" from the inside out. These were not really cracks, but a separation of the wood from between the annular rings. One can see this situation with unpainted wood exposed to the elements for many years; if the erosion is severe enough, the wood almost appears to separate or come apart between the annular rings. This would be an extreme example of raised grain, but we will call them cracks for now. One "crack" eventually progressed through the wall to the outside surface and was crack pinned and filled. The other did not penetrate to the outside of the instrument. I might mention that the grain ran horizontally relative to the instrument's top, thus the cracks were on one side of the upper joint rather than running through the top raised tone holes.

Alan obviously had strong saliva as evidenced by the bore's condition and strong body acids because he was dissolving metal off the keys. He had used good care and maintenance procedures except that he had never used organic bore oil. Consequently, the clarinet had significantly deteriorated over the years before I first worked on it. After the immersion, the clarinet played very well for him, but he stopped playing for two years and stored his instrument without performing any organic oil maintenance. Incidentally, I have found that it's a good idea to oil an instrument's bore four times a year when it's in storage, especially in dry climates. However, you have to remember to remove any excess oil from the bore the next day.

Alan recently began intensively playing his clarinet again, but soon found that his instrument began to perform poorly. He neither eased his clarinet into being played again, nor did he perform any organic oil maintenance.

I spent much time finding the leaks in the upper joint. All tone holes were checked for chipping and four cork pads were replaced because of lime deposit fouling. I also cleaned lime out of all tone holes. The instrument still leaked so I was forced to use a smoke test to find them. I was surprised to see smoke coming out of several post holes, the top triller key guide hole, and the register and thumb tube holes. The second large internal "crack" had progressed into the screws holding the triller key guide in place. Other smaller cracks had progressed into the base of several post holes. After sealing the leaks, I had to give Alan the bad news; his instrument was badly deteriorated when I first saw it and the immersion extended its life for ten years, but the two years of storage with no maintenance finally killed it. He began playing it without oiling it first and he practiced for many hours at a time without frequent swabbing. The instrument was not "blown out", it was worn out! He is still playing it while he looks for a replacement that he likes.

If the reader has any comments or information to offer concerning this article, I would appreciate a letter or e-mail.