The Art Of Making Squash String, Part Two: Building In Performance

By Steve Crandall, Vice President, Sales & Marketing, Ashaway Racket Strings

In our last column (January 2007) we talked about the process of using high tech materials to make string on our “state-of-the-art” 100-year-old braiding machines. But string is made to do a job—which is to be the direct “liaison” in your racquet between you and the ball—and how well it performs that job determines its success in the marketplace. So how do we build in performance? Let’s take a look at two key performance characteristics—durability and playability—and see how string is engineered to provide them.

ASH_Liberty17For the budget conscious among us (which includes me) durability is one of the key characteristics looked for in squash string. Durability is a function of both a string’s core material and its outer wear layer or jacket. Probably the most durable string is a solid nylon monofilament with a wear layer to resist notching. The wear layer on this type of string is also usually made of nylon because of its tremendous abrasion resistance. These wear jackets are not braided, as we described last time, but wound on machines similar to those used to make wire, and then chemically fused to the monofilament core. The result is a single structure that retains its strength and physical integrity even as it is worn down by notching from repeated ball strikes.

This is the type of string usually found on factory-strung or beginner racquets and in other vintage strings such as Ashaway’s Liberty® 17. Of course, the tradeoff for all the durability of monofilament strings is playability. Traditional monofilament strings are stiff and unresponsive, and don’t provide the kind of feel for the ball that helps more advanced players add variety to their game.

ASH_PowerNickTo increase playability, we can alter the construction of both the core and the wear layer. Switching to a multifilament nylon core, such as our SuperNick® XL, adds tremendous elasticity to the string. Multifilament cores are made from thousands of very thin fibers twisted together. This produces a soft, resilient core which, when strung at relatively high tension, provides good power and control, and a good feel for the ball. Unfortunately, some advanced players find that nylon multifilament strings have a tendency to lose tension when used for long periods or at high levels of play, such as in long rallies.

To address this issue, we can switch the core material to a multifilament like the Zyex® fiber found in PowerNick® strings. Zyex is made from a chemical called polyetheretherketone (which you will definitely not find in the cupboard under your kitchen sink), and plays more like natural gut than any other synthetic. It has tremendous dynamic elasticity, which means it snaps back quicker when stretched, and also has excellent tension-holding properties. For this reason, we recommend stringing Zyex at 15-20% less than nylon strings.

Zyex is also very tough and durable. This makes it an excellent material for chronic string breakers, but also more difficult for manufacturers to produce. Multifilament strings use a braided nylon jacket for an outer wear layer. Unlike the wrapped wear layers of monofilament strings, braided jackets are mechanically bonded to multifilament cores using special adhesives, and the chemical characteristics of Zyex increase the complexity of this process.

ASH_SuperNickXLWear layers or jackets, which are almost exclusively made of nylon, affect both the durability and playability of a string. Braiding produces an inherently more durable structure than winding (which is necessary to protect all those thin filaments) and a rougher surface texture, which provides grip, or bite, on the ball to enhance control. Wrapped wear layers generate a smooth surface which provides little bite, but which also makes monofilaments easier to string in racquets.

With braiding, we can alter both the thickness of the material used and the way it is braided—either open or closed—to enhance either durability or playability. Thicker material is obviously more durable, and thicker material combined with a more open braid produces a much rougher surface texture. However, the rougher the surface texture, the more the mains and crosses tend to saw into each other during play, reducing durability. Rougher surface textures are also much more difficult to string than smoother surfaces, as any stringer will attest.

We can also put on two braided jackets—as we do with SuperNick XL to increase durability—but as in all things, there are trade-offs, and there is, of course, no single perfect combination of durability and playability. What string works best for you will be based on your power and skill as a player; your style, frequency and duration of play; and your plain old preference for one type of string over another.