Why is the volleyball made from leather?

The soccer ball was made out of leather in the early years of the game because leather is flexible and durable, and of all the materials available at the time, it was the best choice. Leather was used to cover the animal bladders that formed the air sack inside the ball. Synthetic materials were experimented with as chemistry developed, and eventually leather was discontinued as the construction material of choice. The new synthetic materials were flexible, durable and would permit a ball to retain its shape. Most importantly, the new materials absorbed less water than leather, and water adsorption was always a concern with the leather ball. Just as an aside, today's soccer balls are all synthetic because of the superbly uniform performance of the material and the ability to resist moisture. Synthetic's overall performance has surpassed leather's so it's better for ball construction.