Metal-nylon strings (that is, a steel core wound with nylon) were developed in China in the 1950s as a temporary measure to solve the shortage crisis of silk string production and supplies. Eventually, this type of string replaced silk altogether as they are easier and quicker to produce as well as being far easier to play as the strings are smooth to slide on. Initially, the strings were too smooth and had to be lessened to regain some of the sliding string sounds that were felt to be distinctive of qin music. The strings were very strong and could retain their tuning unlike silk and also they were louder and more stable. A set could last many years and not break. The only drawback for traditionalists was that the strings had a harsh metallic sound which was considered inelegant. Another factor was that the strings could eventually wear the lacquer out requiring the qin surface to be repaired more often. Nylon-composite strings Around 2007, a new set of strings were produced made of mostly a nylon core coiled with nylon like the metal-nylon strings, possibly in imitation of Western catgut strings. The sound is similar to the metal-nylon strings but without the metallic tone to them (one of the main reasons why traditionalists do not like the metal-nylon strings). The nylon strings are able to be turned to standard pitch without breaking and can sustain their tuning whatever the climate unlike silk. The nylon-composite strings have various names such as bingxian (冰弦; "ice strings") or fuhexian (復合弦; "composite strings"). One of the main advertising points of these strings is that they are said to sound very close to the silk strings made prior to the 1950s when silk string production ceased for a while. They were tested on Zeng Chengwei qins and have the backing of Li Xiangting. Hybrid strings In 2016, the Japanese string maker, Marusan Hashimoto, produced what they call hybrid strings for qin. They are made like traditional silk strings but with a Tetron twisted core and for the four thicker strings having a nylon wrapping. Their main selling point is that they can be tuned to standard pitch without breaking and are more stable. Other than that, they are very similar to silk strings, especially in the sound being the closest compared to the other synthetic strings. Properties of the strings Although most contemporary players use