Finishes Used on Native American Style Flutes

Published: 24th February 2009
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A finish is a substance used on raw wood to bring out the color and grain pattern of the wood. A finish is also used to add hardness to the wood fibers and to provide a protective surface over the wood. For me, putting the first coat of finish on a flute and watching the color of the raw wood flash to a deep, rich tone is a satisfying reward after weeks of work.

What type of finish should be used on a Native American style flute? Is there a single best finish? The following discussion will, I hope, provide you with some interesting and useful information that will add to your knowledge of flute making. Armed with this knowledge you can draw your own conclusions as to which finish you think might be best for your flute. This discussion is not intended to be an exhaustive study. The opinions I am expressing about the various finishes are based on my years of hands on woodworking experience. But, they reflect my personal point of view. Other craftsman may draw different conclusions.

You could divide the wood finishes into three general categories - oil finishes, wax finishes and hard finishes. These different finishing materials are sometimes used in combination. An oil finish may be applied first and allowed to dry and then a hard or soft wax applied over it. Or, the flute may be oiled and a hard finish applied over the dry oil. A hard finish may be applied to the wood and wax applied over it. I will begin with a discussion of the oil finishes.

Oil finishes are probably the most ancient type of wood finish. Almost any type of oil may be used as a wood finish. Common vegetable oils make a serviceable finish on wood if applied properly. Skin oil and hair oil have been used as wood finishes. Each craftsman has his favorite type of oil. There are dozens of formulations both ancient and modern. All oil finishes work in pretty much the same way. By penetrating the cell walls of the wood fibers oil can increase the stability and hardness of the woods' cellular structure. Commercial penetrating oils have resins that polymerize (link together) over time and become permanently set in the wood. This helps consolidate and harden the surface of the wood. Oil finishes do not, however, form a very hard, protective surface on the wood. The exception to this is tung, or chinawood oil. Tung oil is an aromatic natural drying oil that is obtained from the nut of the tung tree native to China. When applied repeatedly in thin coats tung oil will produce a beautiful, hard glossy surface. Applying tung oil is a very slow process because each coat takes several days to cure before a new coat can be applied. Tung oil is, therefore, seldom used commercially.

Usually an oil finish is applied with a brush or oil soaked rag. The oil is allowed to penetrate the wood for a period of time. Then, any excess oil remaining on the surface of the wood is wiped (rubbed) off. Some flute makers submerge the entire flute in oil for a period of time. When they remove the flute form the oil bath they drain or wipe off the excess oil. It may take several coats of oil to produce a protective surface on the wood. When oil is applied properly the surface of the wood acquires a pleasant, smooth sheen.

One of the advantages of an oil finish is that it is easy to apply. It does not require any special and expensive equipment. It is also easy to repair an oil finish. Superficial damage to the wood surface such as scratches or dents can be sanded out with a little fresh oil and sand paper. The downside of an oil finish is that it does not provide a very effective protective barrier over the wood. With oil finishes the surface of the flute can be easily stained or damaged. Foreign materials can penetrate the oiled surface and discolor the wood beneath. It is difficult and sometimes impossible to get these stains out. The stains - which are often subtle - may not be objectionable to some. But, they can be a source of annoyance to others. The area around the tone holes and mouth hole are the first places where discoloration is noticed. The discoloration around the tone holes results from oils and dirt on the skin of the fingers. These foreign substances penetrate the surface coat of oil on the flute and are absorbed into the wood beneath. The discoloration and rising of wood grain around the mouth hole results from saliva penetrating the oiled surface and changing the color and texture of the wood beneath.

Oils finishes do not provide much of a protective barrier to the absorption of atmospheric water by the wood. Water transference from the surface of the wood to the fibers beneath can come from absorption of actual water droplets. This is appreciable in the slow air chamber. Or atmospheric moisture (humidity) can be absorbed into the wood from the surrounding air. Moisture absorption is not necessarily harmful to the flute. More significant to the integrity of the flute is the speed with which the water is absorbed or released. Rapid water absorption and loss causes swelling and shrinking of the wood. This can compromise the integrity of the wood and lead to cracking. It can also cause the grain on the surface of the flute to rise. This raised grain will make the wood surface a bit rough.

A second potential problem with oil finishes is that they do not prevent toxins which may be present in some wood species from migrating to the surface of the flute. Once they are on the surface of the flute they can get on the hands and lips of the player. Thus, allergic reactions - though rare - may occur. This is less of a problem with those oil finishes that dry through polymerization (linking) of the molecules in the oil formulation.

A third disadvantage to oil finishes is that they need regular maintenance. Oil applied to the surface of a flute (with the exception of Tung oil) will wear off with time. How quickly this happens depends on the type of oil used, the amount of use the flute is getting and ambient climatic conditions. The maintenance of an oil finish consists of reapplying fresh oil to the wooden surfaces of the flute. Depending on the flute owners' character applying oil can be an opportunity to get deeper into your flute or a messy chore.

Wax is another type of finish used on wooden flutes. Wax can be used as a topcoat over oil or other type of finish. It can also be used alone. The two most common natural waxes are bees' wax and carnauba wax. There are also many synthetic waxes derived from petroleum distillates. Bees' wax is a solid at room temperature. To make it easier to apply bees' wax is usually liquefied by dissolving it in a solvent such as turpentine. A liquid wax is applied to the raw wood surface with a brush or wax soaked cloth. The wax is then rubbed into the wood with a dry cloth. When bees' wax is applied in multiple coats you can get a beautiful semi-gloss sheen on the wood surface. With wax you can get more of a build on the wood surface than with oil. Consequently, it gives the wood a slightly better protective coating than most oils. With wax finishes, like oil finishes, small dents or abrasions to the wood are easy to repair. Like oil finishes, wax must be periodically reapplied to maintain the integrity of the protective surface. Again, like oil finishes wax does not provide a very stable protective barrier against abrasion and staining of the wood by foreign substances.

To my eye nothing beats the appearance and feel of a flute that has been given several coats of penetrating oil followed by an application of bees or carnauba wax. I like the fact that there is no obvious barrier between the wood and me. With this finish the warmth and texture of the wood are apparent to the eye and sense of touch. I also like the way light is diffused as it hits the surface. What I don't like is that the surface of the flute has little protection. Personally I don't like dents and scratches on a flute. I can live with them. They impart a sort of character or history to the flute. But, I don't actually like them. I like having to re oil the flute every once and a while. Most people want to put too much oil on or put it on too frequently. They over oil a flute like most people over water plants. This can lead to a greasy, sticky flute. A properly oiled flute should look and feel dry. You only gain this knowledge through trial and error. And, each type of wood has its own special needs.

There are many hard finishes that can effectively be used on wooden flutes. Each type has its adherents. One of the most commonly used hard finishes is shellac. Shellac is made from the secretions of the Lac beetle native to Southeast Asia. To make shellac hard flakes of this purified beetle juice are liquefied in alcohol. This liquid is then applied with a brush or sprayer. Shellac is available in aerosol spray cans. Shellac penetrates the surface wood fibers and brings out the color of the wood. It also builds a fairly strong, hard surface over the wood when applied in multiple coats. There are, however, several potential disadvantages to using shellac as a finish on flutes. First, most commonly used shellacs impart a yellowish cast to the wood. This is most noticeable with light colored woods like maple or ash. Second, because shellac is soluble in alcohol and many other substances it is not as stable as some of the other hard finishes. A shellac surface is rather soft in comparison to varnish or lacquer. It therefore scratches and dents more easily. A shellac finish has a distinctive (not necessarily objectionable) odor that is detectable even years after it is applied. One of the drawbacks of shellac as a wood finish is that it is thermo plastic at higher temperatures. A shellac surface can become slightly sticky under exceptionally damp, hot conditions. Shellac is a non-toxic substance, even in liquid form. In fact it is sometimes used as a coating over food items.

Varnish is a hard finish made by dissolving a resin in an oil based solvent. There are many resins; both natural and synthetic used to make varnish. When liquid varnish is applied to the wood surface some of the varnish is absorbed into the wood. This hardens the wood surface and brings out the color in the wood. In a relatively short time the solvent evaporates and the remaining resins bond together to form a hard, stable surface with good abrasion resistance. Multiple coats of varnish may be applied to the flute. Each coat is allowed to dry, then sanded to allow the next coat to key to the existing varnish. Then a new coat is put on. In this way it is possible to build a substantial protective barrier over the wood. Most commonly used varnishes also provide some protection from ultraviolet light rays. This helps protect the wood from photo reactive discoloration. Varnish is usually brushed or sprayed onto the wood. It takes several hours to dry. To the best of my knowledge, all types of commonly used varnishes are non-toxic when dry.

For the flutes that I make for sale I have settled on Minwax brand semi-gloss high build polyurethane varnish. It is a commercial product most commonly used on hardwood floors. I spray two coats on with a High Volume Low Pressure spray gun. Most of the first coat gets absorbed into the wood. This hardens and seals the wood. It also raises the grain on the surface of the wood and makes the flute feel rough and fuzzy to the touch. After the varnish has cured for a couple of days, I sand down the raised grain to create a smooth, flat surface. Then I spray on a second coat. The second coat does not absorb into the now sealed wood surface. Instead, it builds a substantial protective coating over the wood. A varnish finish is very hard and stable. It is highly resistant to water and alcohol. It is very resistant to abrasion. That is why it is used as a finish on wooden floors.

Lacquer is another hard finish used on flutes. Dissolving a hard polymer in a solvent called lacquer thinner makes lacquer. Older lacquer formulations were made from the same substance as shellac. Most lacquers are now made from acrylic resins. Lacquer is usually sprayed on the wood. There are also formulations suitable for application by brush. Varnish and shellac harden (cure) by evaporation of the solvent. This leaves behind the hard resin on the wood surface. Lacquer cures by a process of the polymers linking together. This is a molecular bonding process. Lacquer does not need to be sanded between coats as does varnish. The new coat of lacquer melts into the previous coat. Because lacquer hardens very quickly multiple coats of lacquer can be applied in rapid succession. Lacquer does not usually build a surface as thick as most varnishes.

When completely cured (which takes several weeks) lacquer can be buffed to a smooth high-gloss finish. A lacquer surface is a bit harder than varnish and therefore resistant to stains and abrasion. Lacquer is also resistant to the transfer of moisture. It is non-toxic when dry. In my experience the hardness of a lacquer surface has one disadvantage: instead of denting under pressure the way varnish does a lacquer surface may crack of chip. Usually this is only a problem with thick applications of lacquer. Modern automotive lacquers (seldom used on flutes) do not have this problem. Lacquer is used as a finish on most guitars and pianos.

John Stillwell has extensive experience in designing, making and playing Native American style flutes. He has contributed to the evolution and refinement of the Native American style flute.

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