Bowstring

A bowstring is a vital component of an archery system. It connects the two ends of a bow stave together. This connection allows the bow to launch an arrow when the string is released. For a string to work well, it must possess specific properties. It needs to be lightweight and very strong. It also must resist abrasion, which is the wear caused by rubbing.

The mass of the string is also a critical factor. Extra mass located at the center of the string slows the arrow. Interestingly, extra mass at the ends of the string has a similar slowing effect.

There are three primary ways to construct a bowstring: simple, reverse-twisted, or looped. A simple string consists of a single cord made by twisting any fiber. These are quick to create and have been used globally. However, they are often weaker for their weight. They may also fall apart if they are not kept under constant tension. These strings are usually secured to the bow using a knot, a round turn, and two half-hitches.

Reverse-twisted strings are a more advanced construction method. This style is traditional in North America and Europe for many natural materials. To make one, a maker creates separate bundles. Each bundle is twisted in one direction. Then, the entire group of bundles is twisted in the opposite direction. This method produces a string that is stronger for its weight than a simple string. It also holds together more effectively. In a traditional "Flemish" string, a loop is laid into one end. This loop makes it easier to fit the string over the bow's nock. The short section used for the loop is reverse-twisted first before being laid into the main bundles.

Looped strings are constructed using one or more continuous loops of material. Many modern strings are made as a single continuous loop. These are then "served" to reach their final form. A disadvantage of looped strings is that they may have less fiber at the ends. This is a problem because the ends are where wear is most likely to occur. To fix this, makers use serving to add extra protection.

In some parts of Asia, traditional strings use a single loop in the center. The ends are then attached using separate lengths and a special knot. This design allows for extra fiber at the ends where wear is high and weight is less important.

Historically, archers relied on various natural materials. These include linen, hemp, silk, and vegetable fibers. They also used animal products like hair, sinew, and rawhide. Some ancient sources even suggested using the hide of a young, emaciated camel. However, natural materials like sinew and hide are sensitive to moisture. Water can cause these strings to stretch or break. This was a significant weakness in historical combat. One account describes how wet bowstrings could fail during a fight.

Modern science has introduced synthetic materials that are much stronger for their weight. Dacron is a common polyester used for beginners and wooden bows. It has a stretch of 2.6%. This high stretch is useful because it reduces shock to the bow. Other materials include liquid crystal polymers like Kevlar and Vectran. These have a much lower stretch of only 0.8%. Because they are denser and have a smaller diameter, they result in faster arrow speeds. Since the 1990s, ultra-high-molecular-weight polyethylenes like Spectra and Dyneema have been used. These are lighter and faster than Kevlar and have a longer lifespan. Many modern strings use composite fibers, mixing materials like Vectran and Dyneema to combine their advantages.

To ensure durability, makers use a process called serving. Serving involves wrapping an additional thread around the main string. This is done at the nocking points to prevent abrasion. It is also used on looped strings to keep the two sides of the loop together.

This technique is also applied to the cables on compound bows. The extra thread is wrapped around portions that contact the cams, cable slides, or roller guards. This minimizes the wear on the cables themselves and helps the equipment last longer.