Tennis Racket Strings

Tennis racket strings are made from a variety of materials  -  

natural gut, synthetic gut, multi-filament or multi, nylon and

polyester.

These are the principal materials with the addition of Kevlar.

The materials used in making tennis strings can significantly

affect a players performance and even cause injury.

The materials used vary in terms of elasticity, durability, 

rebound efficiency, tension holding and manufacturing cost etc.

Natural gut

Animal intestine is the most resilient material used to make tennis

strings.

It has better tension holding ability than any other material, and is

also softer than synthetic strings.

It provides the most energy return and is thus the most efficient

string.

It remains soft at high tensions while other materials tend to

stiffen dramatically.

This allows players to string their rackets to a high tension which

gives more ball control without losing rebound efficiency or power.

Also without greatly increasing impact shock which could damage

the playing arm.

The drawbacks of gut are its high manufacturing cost and variable

quality control  -  it also is a delicate material and has poor durability

when wetted with water.

The use of a dense string pattern helps spread the rate of wear and

improves the longevity of natural gut.

Pierre Babolat, apparently, first manufactured a natural gut string from

sheep intestine in 1875  -  sheep gut was generally used until the 1960s

when cow gut took over.

A number of top players have enjoyed a hybrid string pattern with natural

gut in the mains and a polyester in the crosses.

The following players have used this set-up  -  Roger Federer, Novak Djokovic,

Andy Murray, Alexander Zverev  -  Emma Raducanu, Aryna Sabalenca, Ash Barty.

Polyester mains  -  more control/spin.

Natural gut mains  -  more power/feel

The string used in the mains (longest string) exerts greater influence over

the shot.

Synthetic gut

Synthetic gut is nylon and nearly always a mono-filament  -  single filament.

Inexpensive to manufacture and cheap to purchase.

Small changes from pure nylon are made to market the string as ''synthetic gut''

  -  textured coatings, colorants and the addition of a small amount of Kevlar.

Multi-filament or Multi

These strings have many filaments in an attempt to replicate the playing 

characteristics of natural gut.

They are generally made of many filaments of nylon, but sometimes

incorporate other materials such as polyurethane, Zylex, Vectran, Kevlar etc.

Multi-filament strings provide better elasticity than single filament strings

but lack durability  -  they also are not good at holding their tension.

Natural gut is much softer which gives more feel and touch to the racket

holder.

Nylon

Nylon is the most popular string material for club and week-end players

due to its low cost, availability and wet weather tolerance.

The improvement in elasticity offered by multi-filament, over mono-

filament, gives a much more responsive reaction of the racket to ball.

Wear resistant coatings are frequently applied to multi-filament strings

to improve the endurance of the strings.

Polyester

Polyester is a very stiff and durable material when used as a tennis racket

string.

Unfortunately because of these very useful attributes it forfeits softness 

and feel  -  it also transmits a lot of vibration back into the racket and

thence to the players arm.

Not good for sufferers of tennis elbow!

A co-poly string is made from polyester and various other additives to

try and minimize the negatives of using only polyester.

Luxilon are now one of the most popular manufacturers of polyester

strings.

The increasing desire for more top-spin to, hopefully, imitate the success

of Rafa Nadal has also added to the greater use of polyester as a string

material.

An alternative approach to using only polyester is to use a mixture of

materials.

Novak Djokovic and Roger Federer (now retired) both use a hybrid 

combination of natural gut as main strings and a polyester for cross-

strings.

This is a useful combination to maximize the positives and diminish the

negatives.

Kevlar

Kevlar Is a very stiff and durable synthetic string  -  first developed for use 

in racing car tyres to replace steel  -  much stronger than steel and lighter

in weight.

This material is very hard to break and is one of the best, next to gut, at

holding tension.

Unfortunately it transmits shock and vibration directly to the arm which

may well cause serious injury and tennis elbow.

If Kevlar is to be used to any extent in racket stringing then the gauge needs 

to be thin and the tension kept low.

Gauge

The ''gauge'' number indicates the thickness of a string  -  a high gauge 

number is thinner than a low gauge number.

Thinner strings offer the player more ''feel'' or ''touch'' but will not last as

long as thicker strings.

Stringing pattern

Rackets are strung with two separate strings, thus four knots, or with a

single string and two knots  -  the difference has only aesthetic value

and appearance of the string job.

All professional stringing is done on highly accurate electronic stringing

machines as made by Technifibre, Prince, Babolat, Wilson etc.

Typical string patterns are 16 x 18, 16 x 19 and 18 x 20  -  the first number

(16 x 18) 16 refers to the number of main-strings in a racket  -  the long

strings.

The second number (16 x 18) 18 refers to the cross-strings  -  the crosses

run horizontally across the racket.

The density of stringing affects the performance of the racket.

An open string pattern (16 x 18, 16 x 19) gives more power and spin

to the ball and a large sweet spot.

It produces a more loopy ball but with a sensitive feel to the shot.

A dense string pattern (18 x 20) gives more control and precision with

a firmer feel -  less spin and a lower shot trajectory.

The Future

Research and development (R & D) continues apace in the aerospace world

and certainly many more polymers and plastics will be invented and discovered.

The emphasis will mostly be on light weight and enormous strength which

fits the needs of a material for stringing tennis rackets.

The other attributes for a good stringing material  -  elasticity, rebound efficiency,

tension holding and manufacturing cost  -  will no doubt be variable.