Strumming, shredding and bending: tensile testing for guitar strings

Published On: September 30 2020


For those of use who learned the classical guitar strung with slightly saggy basic strings, or scraped away on a school violin, today’s modern instrument strings are a whole new breed. Composite materials have helped develop a whole range of strings for both orchestral and guitar players. These can now be made, for example, for the precise guitar type and playing style, but also the player’s personal preferences for brightness of tone or sustained notes.

Strings comes in various gauges (thicknesses), from super-light to heavy, and are measured in 1/1000th of an inch. Therefore a lightweight 9-gauge string is a mere 0.009 inches thick. In electric guitars, the four lower strings strings have an outer layer of would wire, which can be either round or flat.

(For a full explanation of guitar string gauges, outer wire windings, metals used, tonal qualities and detailed comparisons of leading guitar string brands for good measure, check out this website)

String tensile strength testing

The continual development of strings includes the need for various tests to be performed on the strings, with perhaps the most important being the tensile strength. This determines how much tension the string can be placed under before it snaps.

As an article by Zwick Roell explains:

“Strings for string instruments and guitars are high tech products. The newest materials such as plastics from aerospace technology or biocompatible materials such as titanium are used in the manufacturing process. For example, the traditional behavior of a string with synthetic core is specifically influenced for the duration of its life cycle.”

One of the issues of testing violin strings is the thickness of the elements. Strings can be as small as 0.04mm in diameter. The issue is that the testing machine should not distort the test by breaks at the gripping jaw or similar. Some string testing machines therefore use a specially constructed grip rather than a standard solution.

You can see the construction of violin string types in a neat graphic at D’Addario, one of the world’s leading instrumental string manufacturers.


Feel the tension

Non-musicians may not realise just how much tension modern strings can be placed under, especially when playing involves literally bending the strings under tension. This is just as common in jazz and in rock, achieving that slight change of pitch that gives that wail of protest in guitar solos.

You can hear this on almost any solo by guitar god Dave Gilmour of Pink Floyd fames. As Guitar Interactive magazine explains,

“Gilmour is a master at string bending. Inspired by Albert King, who not only strung his guitar upside down so he pulled his strings when he bent them, he also tuned the entire guitar down by a tone and a half, resulting in less tension so he could achieve much larger string bending intervals. Gilmour applied this approach to a regular strung and tuned guitar, and developed a technique whereby he would not only bend regular half and full tone bends, but also as much as two full tones!”

Guitars are big business, and great guitars can command huge sums. When Dave Gilmore sold his entire guitar collection, the star auction lot was his “Black Stat”, which sold for an eye-watering US$3.975million, making it the most expensive guitar ever sold. Gilmore played the iconic 1969 Fender Stratocaster electric guitar on every Pink Floyd album from 1970 to 1983, and on his three solo albums too. The original auction estimate was just US$150,000. Gilmore donated the entire sales proceeds, a cool US$21.5 million, to the fight against global warming.


How much pressure?

Every guitar and violin player has to depress a string to change the pitch, but how much pressure is required? Check out our previous article on research into this very question.

Need to test the tensile strength of strings, wires, filaments, threads and more? Contact us for all your load cell requirements, or to discuss our range of load cells for your testing machines and devices.