There are many factors that cause wood discoloration, mainly divided into two aspects: internal factors and external factors:
1、 Internal factors causing wood discoloration:
Wood is mainly composed of cellulose, hemicellulose, lignin and a small amount of extract. Complex natural polymer compounds contain not only unsaturated double bond and conjugation system of carboxyl group, but also hydroxyl group.
II. The external factors causing wood discoloration are:
Wood is easy to be affected by the external environment, which makes the surface texture of wood loose, rough, discolored and faded, and even the wood loses the fiber attached to the surface, and gradually falls off from cracks or brittle fragments.
3、 The causes and influencing factors of wood discoloration and how to prevent and eliminate them
Photochromism: some materials in wood choose to absorb light with wavelength greater than 290nm, resulting in the change of electrons between energy levels, forming photochromic chemical bond, leading to the change of wood color.
Photochromic protection: block ultraviolet rays; change the structure of light absorbing components in materials, destroy the structure of substances involved in color change, so as to isolate oxygen and capture atomic oxygen, capture free radical extraction solvent
In order to eliminate the phenomenon of light color and restore the original normal color of wood surface, the following two methods can be used:
1. Remove with sandpaper or planer. For fading materials, appropriate dyes or pigments can be applied.
2. Hydrogen peroxide, sodium chlorite and other bleaching agents were used to treat wood, and the color structure system of wood surface was destroyed.