The materials, construction and design of a string will shape its bow response and overall sound. Each string has its very own specific recipe which is determined by months of research and testing. The anatomy of a string designed for violin, viola, cello, or double bass, is usually comprised of four major categories.
The core is the most central part of the string that runs from end to end. Most strings fall into one of three core categories: gut, synthetic, or steel.
Solid Steel Core
Steel core strings arose during the turn of the 20th century, due to a shortage of raw material needed to create gut strings, as well as technological advances in metallurgy and engineering. These strings feature a solid steel wire that runs throughout the entire core of the string. In the case of some violin E strings, this material makes up the entirety of the string itself (no other wrap materials are included).
Solid steel core strings play with a sound that is more projected, focused, and clear than that of gut or synthetic core materials. These have the longest lifetime of any type of string, due to the stability, strength, and resilience of the solid steel core. The solid steel core structure is both durable and relatively simple to manufacture, making them popular for beginning students, as well as those who are economically-minded.
Stranded Steel Core
Stranded steel core strings feature a core made out of thin steel wires braided together in a rope-like formation. Wires of varying diameters are created by a process called "wire drawing," involving the pulling of metal rods through a series of dies, making them thinner and thinner. This gives strings the strength of steel, combined with flexibility and elasticity. The complexity of the stranded steel core also affords strings a wider range of tone than that of solid steel strings, though the general tonal palette is still brighter and more focused than that of gut or synthetic core materials.
While there are many different formations of stranded steel cores, many of them share similar qualities and can often also provide players with easy bow response, often favored by the lower strings, as well as those who play electric instruments or alternative styles (bluegrass, rock, jazz, and others).
These strings feature a core made from synthetic or manmade fibers. Synthetic core strings tend to play with a more flexible, stretchy feel than that of metal or gut strings, as well as a thicker overall diameter. The synthetic materials available to us are quite diverse. For example, a synthetic material like nylon can be made with different elasticities and properties. As a result, string-makers can manipulate these strings to exhibit an assortment of playing characteristics and sound qualities, including gut-like warmth, projected clarity, or balanced evenness.
Some synthetic materials have a higher resistance to humidity and temperature changes, making them more resilient than gut strings. Due to their ability to offer a greater range of tonal variety, these strings are often used by both professional players and advancing students.
Gut strings are made from the small intestines of sheep and cows, and are the oldest type of string-making material. Because of the complexity and elasticity of natural gut, these strings are often warmer and more complex in tonal color. However, they are more susceptible to variations in temperature and humidity, and are the least durable of any strings used today. They are also typically more expensive to purchase than modern strings, due to the more labor-intensive techniques used to manufacture them, along with a high cost of raw materials.