Advance logs tell you why solid wood furniture will change color

Solid wood furniture is favored by consumers because of its superior characteristics. However, many people who buy solid wood furniture will find that solid wood furniture is put in the house for a long time, and the color of the surface will change, especially the light-colored solid wood furniture, which is inevitable for solid wood furniture. Today, advance logs tell you why wood furniture is discolored.

First let's take a look at the discoloration of wood and its classification:

Wood discoloration, in simple terms, is the color change that occurs on the surface due to the environment ( sunlight, oxygen, moisture, temperature ) and microbes ( fungi ) . Wood, sawn timber, and wood products may be discolored. After the trees are felled, the logs are prone to discoloration under the ends of the logs and under the intact bark. After the logs are processed, the sawn timber ( sheets, squares ) is also prone to blue, brown, mildew, etc. during storage and processing. After wood is made into wood products, discoloration may still occur during use. There are many types of wood color change, from wood ( white, light yellow, light brown, etc. ) to pink, red, blue, green, gray, dark gray, brown, taupe, dark brown and so on.

Wood discoloration can be divided into two categories because of its different causes, one is chemical discoloration, including tannin discoloration and oxidative discoloration; the other is fungal discoloration, including mildew and blue ( also known as cyanosis, edge Material discoloration ) . Among them, fungal discoloration is more common, and the impact is more obvious. Generally speaking, wood discoloration refers to the discoloration of fungi.

1. Chemical discoloration of wood

Wood of many species, when exposed to high moisture content or exposed to moist air for a prolonged period of time, can be discolored, not caused by fungal infection of wood, but by chemical reactions of certain components in the wood. , called chemical discoloration. Oxidative condensation of tannins, pigments, alkaloids, sugars, phenols and other organic matter in wood, the most important of which is the oxidation of phenolic substances in wood. Phenolic compounds have a benzene ring structure and are easily oxidized, which is the cause of chemical discoloration. The phenolic compound is colorless before oxidation, and some are soluble in water. After oxidation, a water-insoluble condensate is formed, and the color is red, reddish brown, and brown. Therefore, chemical discoloration is also called oxidative discoloration.

Some wood comprising tannin (tannin known as vegetable tannins), a mixture of polyhydric phenols, when contacted with iron under wet conditions, wherein the tannin can react chemically with the iron (the complexation reaction) to form a single Iron hydride. The iron tannic acid is black and is the main raw material for making ink, thus making the color of the wood black. Depending on the amount of iron and the length of time the wood is in contact with the iron, the color of the wood changes from light grey to blue-black. Similarly, this chemical discoloration occurs in wood by immersing the wood in water with high iron content. In addition, the wood is in contact with copper or copper alloy, and the tannins in the wood react with copper to form copper tannic acid, which also discolors the wood ( light red ) . Chemical discoloration often occurs during the drying process of wood. This is mainly due to the slow drying speed of the wood, especially at the areas in contact with the skid. The chemical discoloration is characterized by a shallow color change and a uniform color change.

Second, the mildew of wood

Moldy wood will discolor the surface and sapwood of the wood, but the mildew has a lighter range of discoloration, and its discoloration is caused by colored spores. Since the spores of the mold only grow on the surface of the wood, the mildew of the wood is limited to the surface of the wood or a layer that is very shallow near the surface.

Moldy often makes the wood green, white, black, and occasionally other colors. The discoloration caused by mold is often flocculated or spotted. In warm and humid climates, or in poorly ventilated environments, mold spores deposited on the surface of wood tend to proliferate and grow mildew.

Moldy wood caused by fungi Trichoderma (Trichodermasp.), Penicillium (Penicillium spp.), Aspergillus (Aspergillus spp.), Mucor (Mucro) and so on. The most important species of Trichoderma fungus is Trichoderma viride, and the surface of the wood infected with this fungus is green. There are many kinds of fungi of Penicillium and Aspergillus, and common species such as Aspergillus niger. After the wood is infected with this mold, the surface is black spots, sometimes connected into pieces.

The adaptability and endurance of mold to the environment and substrate is stronger than that of blue and decay fungi. The mold is also highly resistant to chemical drugs and can grow even when contacted with certain toxic chemicals. Mildew can still be found on some wood treated with preservatives.

As a result of the mildew of the wood, the surface of the wood is only discolored, and the range of discoloration is shallow, so it can be removed by a brush or removed by shaving off the surface layer. Mildew has little effect on the quality of the wood itself and is therefore generally not considered a defect. However, when the mold infects the wood, it can increase the permeability of the liquid to the wood, thereby contributing to the blue change.