Limba VS. Ayous in the second layer

The sweet spot is the area in a table tennis blade where you can strike the ball with optimal energy transfer. If the ball is struck outside that area it will cause torsional instability and loss of energy.

As I said in a previous post, most of the wood’s strength will be along the grain, with little or no strength in the perpendicular direction. That’s why most blades use a crossed grain pattern, in order to achieve stability in all directions. In a standard 5 ply, the core and outer plies are placed vertically, and the medial plies are horizontal. The medial ply plays an important role by adding lateral stability, thus increasing the sweet spot. By putting these layers at 90º we are making the plywood construction more homogeneous in all directions, including along its thickness.

However, this still might not be enough and some 5 ply blades have a rather small sweet spot. The first answer to this were 7 ply blades, these kinds of blades usually have 4 vertical plies and 3 horizontal plies. By having more layers placed horizontally we are creating an even more dense crossed pattern, thus increasing the sweet spot. However, the downside here is that we are compromising longitudinal stiffness to gain lateral stiffness, this basically means that if we compare a 5 and 7 ply of the same thickness and similar construction, the 5 ply blade will be stiffer and faster but with a smaller sweetspot, and vice-versa.

To compensate for the loss of power, 7 ply blades are usually thicker. It’s not uncommon to see 7 ply blades up to 7mm, while 5 ply blades with more than 6mm are far more scarce. Increasing the thickness also means more weight, so it really limits the types of woods we can use. To address this problem a material with a better stiffness to weight ratio is needed. That’s where composite fibers step in.