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A worldwide family
Surprisingly, there are in excess of 400 species of oak offering a vast range in colour, usage and quality. Mature American white oak
(Quercus
Alba) was first identified by early European settlers as an abundant and highly suitable natural building material that offered both strength and a natural ability to repel moisture due the closed cell biology of its fibres. The slow, straight growth of the white oak results in a tightly compact and uniform grain that is ideal for the manufacture of fine furniture. Grown mainly on America’s eastern seaboard, the supply of white oak is carefully managed and regulated by the United States
Department of Agriculture.
Seasoning timber
The process that occurs is a simple one: the stem or branch of the living oak transports hundreds of gallons of water from the ground to its leaves and other branches. When the tree is harvested it still contains much of this water, which must be removed to help preserve the timber. Seasoning is the process of
curing the timber to remove the moisture by slowly heating it in kilns. If carried out too quickly, the void left in the timber by the retreating water will be taken up by the fibres of the wood moving closer together, causing the timber to lose its original shape and warp. It stands to reason, then, that by using the oldest and densest part of the tree (the heartwood) this movement of its fibres during the seasoning process is negligible. The naturally occurring straight grain of American oak is found mostly in the lower, oldest part of the trunk. This in turn contributes to the stability of the wood in ever changing temperatures and humidity.
The Manufacturing Process
Timber will continue to move even after seasoning, so furniture makers have developed several techniques to avoid warps and splits occurring in their finished products. By closely matching the tightness of the grain before bonding separate pieces of wood together to form panels or larger surfaces, the effect of any movement is absorbed by each individual strip of wood as they share identical attributes and therefore the same tolerances. Furthermore, furniture is constructed using narrow strips fixed at 90 degrees to one another which allows them to counteract equally where movement occurs. American oak, like any other wood, is graded according to its rate of growth, age, grain uniformity and density. Good quality furniture will always be made using hand selected
grade I wood. Grade V woods are not satisfactory for long lasting furniture as the wood is selected from the youngest trees and hence the most susceptible to warping or cracking. How successfully the colour and grain pattern of the different strips in furniture match depends largely on the quality of the timber and the skill of the furniture maker. Some craftsmen overcome the problem by adding a layer of
veneer to give a perfect, uninterrupted grain pattern across the whole panel. Aesthetically, this often achieves a very clean finish but the furniture itself can be delicate and therefore expensive and very complicated to repair.
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details of the curing
of the timber process.
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