Ideally, raw materials are uniform, consistent, and predictable. Wood does not offer these qualities but instead varies widely between species. For the purpose of producing a composite product, uniformity, consistency, and predictability are accomplished by reducing separated portions of the wood into small, relatively uniform and consistent particles, flakes, or fibers where effects of differences will average out. Size reduction is sometimes augmented by chemical treatments designed to weaken the bonds between the components. The degree of size reduction and the shape of individual lignocellulosic components will depend on the application.
Different composites tolerate or demand different sizes and shapes.