Bounce Production
All tennis balls are made of a rubber shell with a felt covering, but the type of rubber shell used depends on whether the ball is pressurized or not. A pressurized ball loses its bounce gradually as air seeps out, much as would an inflatable basketball. A pressureless ball retains its bounce indefinitely.
- Pressurized tennis balls are by far the most common type. They typically perform better than a pressureless ball when brand new, but lose their bounce fairly quickly. Many players use them for just one match, then throw them away. A study by Wilson indicates that the typical pressurized ball becomes unplayable after a little more than two weeks. Several companies have come out with pressurized balls designed to last longer. Wilson's Double Core ball has an extra inner coating designed to keep air from escaping. Gamma produces a ball filled with nitrogen, which is supposed to leak more slowly.
- Pressureless balls get their bounce from the structure of their rubber shell, which retains its elasticity without the assistance of air pushing at it from inside. When brand new, they are typically stiffer and less bouncy than a pressurized ball, although Tretorn makes a very lively ball. As they age, pressureless balls get bouncier, because their felt wears down, making them lighter. They are usually discarded when they become so bald that they become too bouncy and lose their normal aerodynamics.
So, of the 24 theoretical ball types, how many can we eliminate?
The following combinations of characteristics are simply illogical:
- Fast with grass court felt, pressurized
- Fast with grass court felt, pressureless
- Fast with extra duty felt, pressurized
- Fast with extra duty felt, pressureless
The following are, to my knowledge, not manufactured:
- Fast with regular felt, pressureless
- Slow pressureless (of any felt type = three possibilities)
A pro shop might have a few more choices. Pressureless balls are worth a try if you want to save money and don't mind slightly different playing characteristics. It might also be worth the trouble to find the rarer slow and fast balls, just for curiosity.
