From an article entitled: Science Friction by Heather K. Scott, from Strings Magazine, October 2002.

(Scroll down for a brief description of How carbon fiber bows are made.)

Introduction:

As the pernambuco forests of South America become alarmingly depleted, bow makers are taking a fresh look at the materials used to construct instrument bows while searching for new ways to improve on tried-and-true synthetic alternatives.

For many years, carbon fiber was thought of as the stepchild of the lutherie world—often ignored and underappreciated. But more recently, makers have come to recognize the usefulness of nontraditional fibers—and players are lauding the craftsmanship seen in these new models. As a result, more professional musicians are using carbon fiber bows in addition to, and sometimes in place of, traditional wood bows. Why? Carbon fiber bows are much more durable than pernambuco bows, they resist warping, are priced economically (especially when compared with their wooden counterparts), and are often very light and well balanced.

Bruce Dukov agrees. He has played professionally for 28 years, performing as a soloist and recording solo albums for CBS Masterworks. His carbon fiber bow experiences had not been positive until a colleague introduced him to one particular model during a recording session. Soon after, the bow became his tool of choice.

"When I played a solo at the Hollywood Bowl last season," he says, "I took into account the irregular weather conditions of playing outside—as well as the necessity of amplification, 18,000 people, a difficult piece—and decided to use a carbon fiber bow over my more 'temperamental' Pecatte. As a result, I was really comfortable, which assisted me in performing with great ease and confidence."

Despite the growing popularity of carbon-fiber bows, many players know little or nothing of how they're made—or what's on the market. And Dukov's story is typical: Some players believe that carbon fiber just can't produce quality sounds comparable to pernambuco. But after trying a variety of carbon fiber bows, most find that there are many that not only look appealing, but produce quality sound—at extremely affordable prices.

HOW CARBON FIBER BOWS ARE MADE

The production of carbon fiber bows involves a peculiar mix of craftsmanship and rocket science. Carbon fiber, a composite material, is made up of two major components: a reinforcement fiber; and a matrix, or resin. This gives the resulting mixture of carbon and fiber mechanical properties that far exceed the capabilities of these separate ingredients.

When we talk about nonwood bows, the reference is usually to either glass fiber or carbon fiber. But the notation of "fiber" as the material used in these bows is a rather broad term. As this article focuses on carbon fiber, let's narrow our look to that synthetic material alone. A more specific term used in carbon fiber bow making is "graphite." When you see bows described as graphite fiber, this means they are constructed from the highest grade of carbon and designed using the most precise standards of manufacturing. The type of fiber used in carbon fiber bow making is called a "pan" fiber (a thermally stable, chemically resistant fiber).

The manufacturing process begins with a thread of material with a carbon base. This material runs through a sophisticated oven where the fiber is stretched and heated in an environment lacking oxygen and rich in nitrogen (this process is called pyrolizing). As the carbon stretches, extraneous atoms burn off until a new carbon substance is formed.

Next, makers must decide what to add to their bow recipe to arrive at a design. Resins are an important part of this stage, and act as a glue holding the fibers together. To make a good composite structure, makers must maximize the ratio of stiffness to weight—and in bow application, they must also understand the acoustic implications of the materials used. Some bow-making companies strive for consistency among all the bows they produce, while others focus on a less expensive product with inconsistent results. The main differences found in the quality of carbon fiber bows are in the ingredients used and the resulting consistency.

Fiber architecture is the last step of the bow making process. Fiber architecture refers to which fibers are present, their configuration, and their orientation. Many companies pour their carbon mixture into molds. (The mixture is either completely dry, partially impregnated with resins, or totally impregnated with resins.) The carbon is placed in the mold cavity and the mold is then closed. The mold is heated until the ingredients solidify or "set." These resins are "thermal set," meaning they cure when heated and can't revert to their previous state. The end product is a highly durable, although very flexible, carbon-based material.

From an article entitled: Science Friction by Heather K. Scott, from Strings Magazine, October 2002