Wood Porosity, Hardness and Base Color

From the first time when mankind knew furniture until today, wood is used as the main material to make furniture. Wood is a natural product with many advantages. Wood is made of tree, which is a renewable material. It can be obtained either from forests or plantations, and with good management, the source will always be available. Wood also has unique and special beauty that cannot be replaced with other materials. Then it is very reasonable if, until now, wood is still the main raw material for making furniture.

But to handle the wood properly is not easy; we need to understand the wood and its characters. The wood is a product of trees, which are living beings. Wood has many species that each have different characters and properties. Wood characters can be varied depending on how the tree is alive and growing during his lifetime. The wood with the same species will have a similar character. But since the tree is the living creature, then there will be some variation in properties according to the condition of the weather, soil, and place where the tree was living. The same type may have different characters when coming from different places.

The characters of the wood must be recognized by the people who work in the woodworking and woodfinishing industries. The basic characteristics of the wood are actually a great value that must be maximized for furniture to make a valuable product. One task of finishing is to maximize the uniqueness of the raw materials that have been there to make valuable furniture. There are at least 4 properties of wood that need to be considered in the finishing process: basic color, grains and pores, porosity, and hardness. They are all must be considered by the finishing people because it will determine the appropriate finishing process for the wood.

wood color variation

• Wood base color

Each type of wood will have different basic colors, such as mahogany wood having a smoothly red color, teak wood having a dark brown color, oak having a brown-green color, pine having a yellow-white color, etc. For finishing with a solid color or an opaque color, the color of the wood will not affect the finished color because the color finishing is completely determined by the color of the stain used. But for the transparent color, the color of the wood base will greatly affect the final color because the final color is the combination of the basic colors of the wood and the wood stain used. The wood with a light color (white) can be finished with more color choices. The dark stains can be used to color the wood to make it dark. If the light color is chosen, then we can apply the light stain.

For the wood that has a dark color, then the options for finishing color are quite limited; there is no stain that can lighten the basic color. The finish color is limited from the wood base color to the darker. When we choose the finishing color, we have to consider the basic color of the surface that is already there. The color of the finishing we choose cannot be lighter than the basic color of the substrate. If the final color desired is lighter than the basic color of the wood, the bleaching process is needed. Bleaching is a chemical process to lighten and whiten the wood. The bleaching process is tough, costly, and dangerous, so it should be avoided as much as possible. Therefore, selecting the final finish color according to the base color of the furniture substrates is the best way. Use the wood with the light base color if the light finish color is needed; use the dark wood for the dark finish color. The right selection of the substrate will ease the process of finishing and reduce the finishing cost.

• Wood pores and grains

Each type of wood has a different pattern of grains and pores. Grain is the result of the cambium developed during the growth of the tree. It is mainly determined by the species of the tree and how he lives. Some types of wood have very strong and clear grain character, such as teak, mahogany, rosewood, walnut, etc. While some other woods have a vague and soft grain character, such as aghatis, sengon, ash, etc. 

Wood pores are holes that are found in the wood. These pores are also formed when the wood grew during his lifetime and depend on the wood species. There are several types of wood with big pores, such as oak, mindi, teak, etc. While other types of wood only have small and shallow pores, such as maple, ash, beach, etc. But the character of the wood also depends on how the tree was living. Then the pores and grain patterns of the wood also depend on the place where the wood comes from. Sometimes we find the wood with the same species has different grain and pore character. For example, we can find some oak wood with smaller and fewer pores, while at the other time we may find the oak with bigger and more pores because it comes from a different place.

The pattern of wood grains and pores is actually one of the uniqueness and great value of wood that should be enhanced in the finishing process. The finishing should adapt and follow to the pattern of grains and pores in the wood and maximize his performance. The wood with strong character grains should have a proper finish to maximize its unique character, including the grains and pores pattern.

• Porosity 

Porosity of wood is the wood's ability to absorb liquids. There is some wood that has high porosity, such as sengon wood, pine, aghatis, etc. They will absorb more finishing materials in the finishing process. This wood will need more coating materials to achieve the smooth surface and film built. Meanwhile, at the stain application, the wood with a high porosity will absorb more stain and tend to generate the dirty or dark color. To avoid this problem, we can use the thin and sprayed lightly in many times. For some types of wood that is really soft, we may need to do the sealer or glue sizing (see our other article: glue sizing for wood finishing).
There is also some wood that has very low porosity, such as hard mahogany, walnut, rosewood, etc. They are less in absorbing finishing materials and sometimes make the finishing materials difficult to wet the wood. For this type’s wood, we also need some modifications in the finishing process. We can use the slow-drying stain to let the stain wet and soak the wood and color the pores and grain to maximize the wood finishing color.

• Hardness of wood

Wood also has different hardness depending on the species of the wood. The hardness of the wood also needs to be understood since it will determine the proper process of sanding. The hard wood has stiff wood fibers that are easy to be cut in the wood sanding. The hardwood is easier to be sanded to produce an even and smooth surface. Meanwhile, the soft wood is usually more difficult to be sanded because the wood has more elastic wood fibers. The fibers tend to "lay down" in the sanding process. The softwood needs more sanding steps. We need to do sanding gradually with less jump grade sandpaper from the beginning to the end. We also need to replace the sandpaper soon after it is blunt and cannot cut the wood fibers
Imperfect sanding will result in the uneven absorption of the stain applied. It led to a blotchy or spotty color in the finishing. To overcome this problem for some soft wood, we can use a wash coat application before the sanding process. The wash coat or sealer will wet and wrap the wood fibers and stiffen them when they dry. Then the stiff and hard wood fibers are easily cut in the sanding process to produce an even and smooth surface.