Editorial: Of rackets and strings

On Tuesday, I went to the US Open, the premier US tennis tournament and, along with Wimbledon and the Australian and French Opens, one of the four ‘Grand Slams’ of the tennis world.

I’m also a player (not a very good one), so I thought I’d devote this editorial to how polymer chemistry has changed the game of tennis. Many thanks to Wikipedia and various tennis websites for their help.

If you look at late-1970s photos of John McEnroe—the famous tennis brat and only slightly mellowed current tennis commentator—you’ll see he played with a wooden racket. Such rackets were suited to slice shots and a lot of volleying and net play. They were not for high-power games.

Even as McEnroe was winning with wood, other racket materials were emerging. Stiffening graphite sheets were inserted between the layers of some wooden rackets. Jimmy Connors won Wimbledon in 1974 and 1982 with the steel Wilson T2000 frame.

Eventually, composites of epoxy resin and carbon fiber (made by thermally decomposing polyacrylonitrile) took over the market by allowing the construction of larger, stiffer rackets. Players responded by radically changing their grips, allowing them to swing in a low to high motion and generate the power and topspin that characterize today’s games. The serve-and-volley style of McEnroe is mostly a thing of the past.

I personally play with Yonex rackets, which are made in Japan. The retailer Tennis Warehouse visited the Yonex factory in Niigata, Japan, and produced a very informative video on how the brand’s rackets are constructed. Most other rackets—including most of those from Wilson, Babolat, and Head—are made in China. But wherever they are made, it’s a surprisingly manual process.

Those wooden rackets were typically outfitted with strings made from cow gut—not catgut, as myth would have it. But just as polymer chemistry was changing the racket frame, it was also changing the strings.

The first polymer strings were so-called synthetic gut made from multifilament nylon 6 or 6,6. Then in 1997, the Brazilian player Gustavo Kuerten won the men’s French Open title with a new kind of string: monofilament polyester. These strings are typically made of the same polyethylene terephthalate found in clothing and water bottles. Some companies also blend in thermoplastic polyester elastomers or other polymers to soften the feel of hard polyester.

Today, polyester is the dominant material in the strings used by professional players. It yields a stiff, unresponsive string that allows players to swing hard from low to high. The resulting spin keeps the ball on the court per the Magnus effect, which describes how a spinning object moving through a fluid dips more than would be caused by gravity alone.

But the string world is quite varied. Nylon synthetic gut is still used, generally by beginners and on inexpensive rackets. Kevlar strings are also available. And natural gut is still loved for its controllability and gentleness on the arm. The recently retired tennis greats Roger Federer and Serena Williams both used a hybrid of gut and polyester—gut in the longer vertical direction and polyester in the crosses.

From a very unscientific survey of tennis string packages, I’ve concluded that Taiwan is the polymer string–making capital of the world. For a while, I reasoned that using a hybrid setup would help me play like Roger and Serena, and I bought Klip-brand strings made from Australian cow gut. My theory, of course, proved untrue, and I switched to a polyester blend.

And while the French tennis firm Babolat now makes its rackets in China, it still operates a natural-gut factory in Ploërmel, France, where it takes the guts of two cows to make one set of strings, according to the company’s website.

At the US Open, I watched a match between Andy Murray, who won the tournament in 2012, and Corentin Moutet. They could have been using frying pans instead of rackets and they would have been great, but they definitely got some help from polymer chemistry.

Views expressed on this page are those of the author and not necessarily those of ACS.