NATURAL COLOUR OF WOOD (Part III)
Natural color of wood can change rapidly due to several causes, either by extractive substances contained therein as well as by influences from outside the timber. Examples of mahogany (Swietenia macrophylla) the color changed from pink or light red to red brown quickly on a piece of wood fresh. This color change can lead to defects in the wood color defects. Another term often used is the discoloration.
Discoloration is caused by defective color color changes which occur in wood caused by a variety of treatment without giving the dye. There are five factors that cause the occurrence of staining, namely: the influence of temperature and humidity, the process of oxidation, deposition of pigment on the surface of the wood, the influence of the organism and in contact with metal.
The color of wood exposed to the atmosphere often darken the wood and sapwood usually be darker than the wood paneling. These changes usually occur in the natural chemical produced by the oxidation reactions of organic components contained in the wood.
The color change can occur immediately after trees felled in the forest or wet after sawing logs into boards. Alder wood quickly changed color from whitish to reddish, then fade to brown. Black locust wood porch changed from light green to dark brown, while the Douglas fir becomes reddish.
Further stated also that the old wood exposed to sunlight, especially in the high plains, changing its color to brown. While prolonged exposure to rain or high humidity change the color of the wood becomes dark gray.
Discoloration on teak (Tectona grandis Lf) caused by the oxidation process of extractive substances in the wood. As well as the study of sugi wood (Cryptomeria japonica). From some research it is known that the use of high temperatures in the drying of wood has caused the color change. This is caused by the discharge of extractive substances contained in the timber to the surface. As for the wood white or light colored wood and the sapwood, the changes can be caused by fungal attack. Wood is attacked is usually a blue or black. Generally, the wood was attacked while still in fresh condition with a high water content.