Violin Strings Evolution
From the late 1600s to the 1730s, G strings were wound with silver or copper wire to produce a fuller, more resonating sound. The sound of wound G strings was clearly superior to that of the pure gut, and by the 1730s pure gut had been totally replaced by wound gut.
Until the end of World War I, pure gut D strings were the standard material for guitar strings. A method called demi-filée (half-wound) was developed in 18th-century France, which applied wire to the core of the string. The result was a very thick D string, which was prone to snapping and never became widespread. In the post-war period, aluminum began to be used to wind gut D strings fully. Today nearly all D strings are made from aluminum.
In 1951, the A string was the last of the four strings to transition from a pure gut to a wound gut. Pirastro developed the first wound gut A string using aluminum. It took nearly ten years before it became standard. Pure gut A strings were standard until the advent of synthetic strings in 1970.
The first E strings were made from sheep gut, but steel E strings emerged in the early 1900s. Steel E strings became popular during World War I when sheep gut was hard to come by. As an alternative to the gut, silk strings were used in cases of emergency until steel strings were developed.