The strings of the guqin Chinese zither are either made of silk, nylon or metal-nylon. Overview Until modern era, the guqin's strings were always made of various thicknesses of twisted silk 『絲/丝』, but since then most players use modern nylon-flatwound steel strings 『鋼絲/钢丝』. This was partly due to the scarcity of high quality silk strings and partly due to the newer strings' greater durability and louder tone. Silk strings Silk strings are made by gathering a prescribed number of strands of silk thread, then twisting them tightly together. The twisted cord of strings is then wrapped around a frame and immersed in a vat of liquid composed of a special mixture of natural glue (ingredients include Bletilla striata and isinglass) that binds the strands together. The strings is taken out and left to dry, before being cut into the appropriate length. The top thicker strings (i.e. strings one to four) are further wrapped in a thin silk thread, coiled around the core to make it smoother. According to ancient manuals, there are three distinctive gauges of thickness that one can make the strings. The first is taigu 〖太古〗 [Great Antiquity] which is the standard gauge, the zhongqing 〖中清〗 [Middle Clarity] is thinner, whilst the jiazhong 〖加重〗 [Added Thickness] is thicker. According to the Yugu Zhai Qinpu, zhongqing is the best. However, these three gauges have practical relevance as thinner strings sound better on thicker instruments and vice versa, compensating for the thickness of the instrument and thus the potential tone and volume. The Taigu brand of silk strings indicate that the zhongqing gauge is suitable for longer qins, made of Chinese fir and/or have a thicker top board whilst the jiazhong gauge is suitable for shorter qins, made of paulownia and/or have a thinner top board (the taigu gauge being suitable for all). Recently in China, production of very good quality silk strings has resumed and more players are beginning to use them. The American qin player and scholar John Thompson advocates for the use of both silk and nylon-wrapped metal strings for different styles of qin music, much like the guitar exists in both classical (nylon-string) and steel-string forms. Playing silk strings is different from playing metal-nylon one, as you need to pluck much more gently in order to avoid buzzing and the string slapping on the surface. Thus, silk strings are slightly more difficult to play. Metal-nylon strings