Wood as a natural organic matter, internal loose porous and contains a lot of water and oil, internal damping is large, easy to cause sound vibration attenuation so as to affect the tone of the guitar. At the same time, wood is hygroscopic. Even after being cut down for many years, it will still expand or contract accordingly with the humidity change of the surrounding environment, which easily leads to the structural deformation of the guitar. Dealing with the inherent instability of wood is something that guitar makers and guitar players need to pay attention to. The process of wood drying and fine processing is essential, and it is also a very important step in the production process. The research and development department of KEPMA finally decided to adopt two wood drying methods: RCS (Rapid Cellular Stablization) and HTT(High Temperature Torrefied) drying technology. In order to achieve the desired effect, KEPMA Guitar and Nanjing Forestry University jointly developed a systematic wood drying treatment equipment in 2019, which can be set through different procedures to make the RCS/HTT technology actually play a role.
HTT--High Temperature Torrefied
HTT technology refers to a further drying technology than ordinary wood drying technology. The drying treatment temperature will gradually rise to about 130 degrees, and slowly reduce the equilibrium moisture content of wood to the predetermined target range.
In the process of HTT drying technology, a large amount of water, part of oil and hydrophilic substances inside the wood will slowly precipitated and permeated into the surface of the wood, and the wood will gradually become lighter, harder and brittle, which is not only beneficial to reduce the sensitivity of the wood to the change of environmental temperature and humidity, but also beneficial to reduce the energy attenuation in the process of vibration transmission and enhance the responsiveness of the wood. In particular, the acoustic properties of wood as top will be significantly improved, and the timbre potential is easier to be stimulated.
RCS--Rapid Cellular Stablization
RCS technology refers to the process of making wood undergo a longer period of high temperature and humidity treatment under anoxic conditions (RCS temperature will reach about 160 degrees) on the basis of HTT technology. When wood is in this extreme EMC environment, its internal hemicellulose will degrade, and the hydrophilic groups will be reduced. In other words, the wood treated by RCS technology can better adapt to the change of environmental temperature and humidity in the future, and is not easy to absorb or release water for expansion and contraction, resulting in deformation. At the same time, in the process of RCS, it can be found that the crystallinity of the wood is increased, and the internal structure strength of the wood is improved. During RCS, the wood will continuously release a large amount of oil and part of water, so the density of the wood will become smaller and the internal damping will become smaller. These changes are more conducive to the acoustic advantages of wood, and the vibration of the strings will be efficiently transmitted and converted into a crisp and loud sound.
