Category Archives: Polyester

String Evaluation Program

Racquet Quest, LLC has for years been doing the extensive evaluation of racquets and string for the benefit of our client’s customization requirements.

Now we are making this evaluation “program” available to anyone that wants to dig deeper into the workings of the string in the racquet!

This is serious stuff and requires significant resources but it is worth it!

Please contact us of you would like to take advantage of our evaluation program!

Take a look at the String Evaluation Program!

 

 

In a string does color matter?

Of course color matters!  Brands have made history on color!  Prince Green, Head Orange, Babolat Blue, for racquets but what about string?

Sure, again!  Luxilon Silver, Babolat Black,  Solinco Green, Victrex Putty…what?  Which of these monofilament strings do not have any color pigment?

If you guessed the Victrex you would be correct.  But why not?  The natural color of the polymer is probably the very strongest a string can be, however, without color they would not be at all interesting or recognizable!  The natural Victrex color is typically what we use when evaluating the string because it is visually different.

Victrex does make strings with black-pigment, but this post is about the difference pigmentation can make in a string.  In a previous post some years go we determined that color had very little affect on string properties and this evaluation shows pretty much the same result in a different format.

You can see by this graph there is very little difference between the two Volkl V-Star strings.  In fact it would be safe to say the strings are identical.

We will continue to evaluate strings with pigmentation to determine if any color does exhibit an affect on the properties.

Dealing with Options, and What are the Options?

The little video you see above is just a reminder that we do not promote polyester based string for underage players!  So, what is underage?  Oh, under 100 would be a good number, I think!

OK, smart alec what are the options?

  • No Polyester

PEEK/Zyex

Well, there are many, however, if the option is only relative to “no polyester” the best option is PEEK material.  This material is usually referred to by the brand name Zyex which is the fiber division of Victrex of England and known by the Ashaway name as well.  This material is normally found as a monofilament construction as is most polyester materials.

PEEK/Zyex offers exceptional durability and energy!

Multifilament

  • Premium Playability

Natural gut still is the number one playing string available.  We use Babolat and Luxilon natural gut but there are other options like Pacific, Klip, and others.

  • Excellent Playability

Multifilament construction can act as a spring and return both performance, power, and comfort.  Typically the more individual fibers the better.  These fibers are usually bonded with a soft adhesive and show signs of “fraying” during use.

Strings in this category include Tecnifibre, Ashaway, Babolat, Head, Yonex, and Gosen and others.  Expect to pay $42.00 + for these strings installed.

  • Playability

These multifilament strings are typically constructed using fewer larger diameter fibers to enhance durability.  The same “fraying” occurs with this grade of string as well however the larger diameter will last a bit longer usually.

Strings in the category include Tecnifibre, Babolat, Head, Yonex, IsoSpeed, Gamma, and others.  Expect to pay between $35.00 and $40.00 for these strings installed.

Synthetic Gut

  • Value

There are probably 10000 strings that fall under this umbrella!  9999 of these strings will be a nylon core with one or two overwraps bonded to the outer surface.  This material and construction has been around for many, many years and has offered great service to millions of tennis players…and is still in major use today!

Strings in this category include at least one, and probably many more, set from every major brand!  If you are really cost-conscious do not overlook this material. Expect to pay $27.00 to $35.00 for these strings installed.

And lastly,  what is our gripe with polyester?  Click on the link below to find out!

Click here to go to a comprehensive post that will explain our position.

As always, our position is “there are no bad strings just bad applications!”

 

What Can String Failure Tell Us – Part Deux

In Part Un we discussed the difference between shanking (mis-hit) and friction failure.  It was obvious that the string was broken.  But what happens when it is not so obvious?

Part Deux, this part, will examine the frictional notching failure of monofilament string and how we can be prepared for it!  To further refine this discussion we will be comparing PET polyester has PEEK monofilament string.  The reason is that each material while both will notch one requires more time to reach the critical dimensional decrease that is a failure!

In almost every Racquet Quest Podcast we talk about tension v string diameter and agree that once 50% of the string diameter is notched away the string is vulnerable!  So a .050 (1.27mm) diameter string that has a tensile strength of 120 pounds at 50% notching will have 60 pounds of tensile strength remaining.

Notched v un notched string

This graph is a string that was broken during use.  The string was removed from the racquet.  The top line is the tensile strength in the area of no notching so you can see that it is pretty strong still and has stabilized due to use.  That stabilization is indicated by the very tight stress/strain grouping.

However, things go sideways when the notched area of the string is put under stress.  The string failed at a force of 63.8 pounds, or about 59% of the used tensile strength.  Not bad!

So, notching is failure-inducing but how long it takes to create the fatal notch differs with string material.  This particular set of strings had about six (6) hours of play.

In Part Trois, we will look at PEEK material under the same conditions!

 

What Can String Failure Tell Us?

Well, in the simplest terms, failure tells us it is time to have the request strung! However, there may be subtleties in string failure that can help us in our quest for tennis racquet performance.

Such as?

Is the failure shear related or tensile strength related? Was friction the major contributor to the failure? Where did the failure occur (on the racquet, not the court)? Was the failure during play or in the bag?

Shear-related failure is when the string breaks very near the racquet frame. This failure is called a mis-hit or shank! It is like cutting the string with a pair of scissors!

Shear Failure

Friction Failure

Friction failure is caused by just that, friction!  Friction is caused by the string moving on each other. That rubbing creates friction and notches the string where it will fail.

If the racquet failed during play and it is not shear-related, the tensile strength of the string was exceeded. If a string has a tensile strength of 120 pounds and the tension is 60 pounds leaving 60 pounds to be used to hit the ball. Some big hitters can generate at least that much force on a solid forehand!

The graphs show the tensile strength and relative elongation of different material.

This graph shows the tensile strength of the string to be about 115 pounds.  Given the movement of this string-on-string, the frictional notching can contribute to relatively early failure based on the hitters force.

This graph shows the tensile strength of the string to be about 155 pounds but it has to travel (stretches) further to reach that force.

So, you can see, with this information we can make better decisions when asked to suggest a string, or strings, for a client!