There are essentially two main ways how to inflate tennis balls, neither of which is typically available for the average person to do on their own. One method involves a chemical reaction resulting in the ball inflating and the other utilizes compressed air.
Inflating tennis balls using a chemical reaction:
- The manufacturer first assembles the core of the ball (the rubber part before the green fuzz is added). This method usually uses sodium nitrate (NaNO3) and ammonium chloride (NH4Cl) which combine to give off nitrogen gas during the molding process.
The other method that uses compressed air is common in tennis ball manufacturing, but neither method can really be employed by the "Average Joe." Tennis balls are made to die. Tennis balls have a usable life span of about two to three months after which they begin to deflate. Once the tennis ball starts to lose its air, it cannot be re-inflated. They can be recycled for other uses, such as covers for chair feet or tow hitches, dog toys or to fluff clothes in the dryer.
Inflating tennis balls using compressed air:
- The two halves of the ball shell are assembled, trapping the compressed air inside at the appropriate pressure. Tennis balls are generally pressurized to approximately twelve pounds per square inch. Rubber is a permeable compound and the seal on the ball shell may be sufficient to hold the inflation for some time, but the air will seep out, gradually resulting in a deflated ball.
- Following the core assembly and inflation, the outer rubber is buffed and coated to prepare it for the fabric covering (the green fuzzy part). The fabric coating is put on the core in two pieces, almost resembling a peanut shape. Once fitted, the ball is placed in a mold to cure its coating and shape.
- This also cures the rubber that runs along the junction between the two pieces of fabric covering (the light gray stripe that curves around the ball). The balls are then steamed and tumbled to soften or fluff their appearance and feel before branded (depending on the company that makes them) and packaged for sale.
- Tennis balls are meant to be replaced every couple of months or so, if not needed sooner. For this reason, tennis balls made with compressed air. These Tennis balls are packaged and sold in pressurized canisters to help prolong their life between production, sale and use. Once the ball has deflated or if it splits open for whatever reason, it's best to just replace it.