Often described as catgut, natural ‘string’ is actually prepared using animal intestines usually from sheep, goats or cows. It has been in use for centuries for making the strings of musical instruments, sports rackets, bows, clockmaking and medical sutures. The transformation of the intestinal walls of animals into a usable string is a highly skilled process, and although still the material of choice for some, these costly strings have largely been replaced by synthetic alternatives. 

The first tennis rackets used natural gut but by the 1950s synthetic strings were being used as a more durable and less expensive alternative. Some synthetic strings replicate the more desirable characteristics of natural gut whilst others are engineered to create spin, such as the polyamide (nylon) Prince Topspin (1), that has a centre core for strength and a textured wrap. The Kirschbaum Multifibre string (2) has a durable polyamide multifilament core with a polyurethane coating that helps to absorb vibrations, minimise shock and protect against wear. The Ashaway MonoGut (3), made from polyetheretherketone (PEEK), provides dimensional stability and good wear, abrasion and fatigue resistance. The Dunlop Aerogel 200 racket (4) is strung with polyester monofilament; some grades of polyester string are known to deliver topspin.


Traditionally gut and steel were the standard materials for the strings of most instruments. Gut strings produce a warm, rich tone but are affected by changes in humidity and are expensive. Introduced in 1948, the first synthetic guitar strings were made from nylon which by 1950 had also become the standard string for the ukulele (5). They were affordable and appreciated for their durability, smoothness, and ability to remain in tune. The strings of the Aquila violin (6) are made of aluminium and silver on a Perlon (nylon) core which is little affected by humidity, responsive and, once again, affordable.


Materials used for the strings of archery bows traditionally included vegetable fibres, sinew and gut. They needed to be lightweight, strong and resistant to abrasion. Modern materials provide these characteristics combined with reliability and affordability. This bowstring (7) is made from a blend of ultra high molecular weight polyethylene fibre and polyester fibre spun from liquid crystal polymer.