“Once we worked out those kinks, string manufacturers like Ashaway [Racket Strings] began using Zyex. Our biggest dilemma then was maintaining precise gauge control for the narrow filaments they wanted us to produce. It was only dedicated manufacturers like Ashaway that were able to design processes that corrected for this shortcoming.”

As string manufacturers did begin making string with Zyex, they and the corporation alike were immediately excited about the results. Strings made with this new material promised to give a previously inconceivable combination of superior properties:

What’s more, Ashaway Line & Twine Manufacturing Company has succeeded in adapting its proprietary multifiber processing, used in making the world’s finest medical and ophthalmogical suture thread, to manufacturing a second generation of Zyex racquet string and racquet string cores. Thinner gauge Zyex fibers with improved “packing density” now allow Ashaway to make a string with more filaments per cross-section than ever before. The marriage of this advanced filament material, and Ashaway’s string manufacturing technologies, resulted in the thinnest and most “playable” high-performance racquet strings.

Ashaway’s Zyex strings are a three-layer construction which incorporates a thin but highly packed multifilament Zyex core, a braided nylon covering to provide additional strength for a long-playing life, and a special coating to unify the structure and eliminate movement and “sawing” at the crosses. This construction gives players a number of significant advantages even in comparison to other new high-tech offerings.

Dynamic Stiffness
If you watch a slow-motion photo of a ball hitting a tennis racquet with nylon strings, you will notice that the strings are very flexible during initial impact. However, the farther the strings are stretched, the stiffer they become. This stiffness eventually causes a significant amount of deformation in the ball before it leaves the racquet head.

With gut, a different pattern occurs. The strings stretch more completely, forming a deeper pocket in the strings and creating far less ball-deformation before the ball reverses and flies off the racquet head. Minimized deformation of the ball improves control. Many players prefer natural gut string for just this reason.

Gut also springs back more quickly than nylon. This improved recovery makes the strings more lively. Ashaway string made with Zyex fibers offers the same improved resilience and lack of ball deformation as natural gut.

While the dynamic stiffness of gut and Zyex are comparable, the dynamic stiffness of nylon is significantly higher than either. Zyex gives vastly superior resilience over nylon, Kevlar and other string materials.

When it comes to dynamic stiffness and responsiveness, no other stringing material comes as close to natural gut as string made with Zyex from Ashaway Racket Strings.

Thin Strings
Advantages resulting from the low dynamic stiffness of Zyex become even more pronounced as strings become thinner. The ability to consistently make high-quality, ultra-thin Zyex filament is resulting in Zyex strings as thin as, and more playable than, anything else available.

Thin strings also mean more bite on the ball. Because Ashaway can manufacture the raw Zyex materials into micro-gauge string, players will notice excellent grip on the ball, translating into improved shot-making.

Improvements in filament denier, purity and packing density now make it possible to manufacture Zyex strings in narrower gauges than previously possible: Tennis—17 gauge, Racquetball—17 gauge, and Squash—18. This is not the end of the line. Ashaway anticipates developing processes to make an even narrower gauge string for each of these sports. Zyex strings will one day be available for badminton, starting at 22 gauge, with narrower gauges anticipated in the future.

Tension-Holding
Zyex does not lose tension as quickly as nylon, nor gut for that matter, so the racquet has to be strung at 10–15% less initial tension than nylon to achieve the desired result at playing time. When nylon or gut is strung into a racquet, it loses up to a quarter of its original stringing tension before the player makes it onto the court. Zyex, on the other hand, does not lose nearly as much tension. To get playing tension with Zyex equal to what you are used to with nylon or gut, you will only need up to 60 pounds of stringing tension (tennis). Players who mistakenly have their racquets strung at tensions appropriate for gut or nylon will get a racquet that is much tighter, and much less satisfying to play with.

The big advantage of Zyex’s superior tension-holding is not the lower initial tension, but rather its long-term holding power. Recently, Zyex Ltd. measured the tension of Zyex-strung racquets that have had little, if any, playing time over many years. They discovered that racquets strung with Zyex as long as 15 years earlier still had almost the same tension. This does not eliminate the need for a competitive player to string his racquet frequently. What it does mean is that players will have to make fewer, if any, adjustments in their style to accommodate changing racquet tension.

While gut has somewhat better dynamic resilience than Zyex, natural gut has a very poor tension-holding ability, which is why it is used infrequently. Another material with superior tension-holding ability is Kevlar. Zyex, however, holds tension relentlessly without sacrificing liveliness. The difference is evident when you hear the sound the two strings make. A clean hard shot made with Kevlar strings makes a dull “thud.” The same shot made with Zyex strings creates a satisfying “ping.” This is the sound of a very lively string.

In fact, Zyex strings are so lively, that they are used by premier string instrument manufacturers for violins and violas. Not that you should be tempted to start a string quartet with Ashaway racquet strings—there are some differences. Ashaway, in fact, had to add a sound-dampening process to their manufacturing process, to avoid the distraction that even beautiful music would cause on the court.

Weatherability
Heat and moisture are enemies of racquet string. Heat in the environment itself, and heat generated within the strings, cause nylon strings to get stiffer over time and degrade prematurely. However, temperatures between -60°F and 300° F have virtually no effect on Zyex strings.

Advantage—Ashaway and Zyex
The bottom line is that players who have found Zyex strings wanting in the past should take another look. Ashaway strings made with Zyex offer an unbeatable combination of playability, liveliness, durability and weatherability. Zyex and Ashaway have the right combination—thin strings that sacrifice neither liveliness nor durability, while providing superior grab and feel for great top-spin and touch shots.

Zyex is a registered trademark of ZYEX Ltd.
Kevlar is a registered trademark of E. I. DuPont de Nemours & Co. Inc.