Ping pong balls are made by molding two hollow half-shells of plastic, bonding them together with a chemical solvent, then sanding, polishing, and testing the finished sphere. The entire process transforms flat plastic material into a ball that must weigh exactly 2.67 to 2.77 grams and measure 40 millimeters in diameter. What looks like a simple hollow ball actually goes through a surprisingly precise manufacturing sequence.
The Material: From Celluloid to ABS Plastic
For over a century, ping pong balls were made from celluloid, a semi-synthetic plastic derived from plant cellulose. Celluloid gave balls a distinctive feel and bounce, but it came with a serious drawback: it’s highly flammable. Shipping large quantities of celluloid balls created genuine fire hazards during transportation, and the material was expensive to produce safely.
In July 2014, the International Table Tennis Federation made non-celluloid plastic balls mandatory for all sanctioned events. Modern balls are made from ABS (acrylonitrile butadiene styrene), the same type of durable plastic found in LEGO bricks and computer keyboards. ABS is cheaper, far safer to transport, and can be manufactured with tighter consistency. You can still find celluloid balls on the market, but competitive play has moved on entirely.
Molding the Half-Shells
Every ping pong ball starts as two separate hemispheres. The raw ABS plastic is heated until it becomes pliable, then shaped using one of two methods depending on the type of ball being produced.
For traditional seamed balls, thin plastic sheets are stamped or compression-molded into half-shell shapes using metal molds pressed together under high pressure. Each mold is machined to precise dimensions so the resulting hemisphere has uniform wall thickness. The edges of each half-shell extend outward into a small flange, a flat lip that will later be used to join the two halves together.
Seamless balls use a different approach entirely. Instead of bonding two halves, the whole ball is injection-molded as a single hollow sphere using a specialized mold. This eliminates the seam line and produces a ball with more uniform wall thickness, which can improve consistency in bounce and flight. Seamless balls are generally considered higher quality, though both types are used in competition.
Joining the Two Halves
For seamed balls, the bonding step is critical. A solvent, typically acetone or ethyl acetate, is applied to the flange surfaces of both half-shells. These solvents don’t act like glue. Instead, they temporarily soften the plastic itself, allowing the material on each flange to fuse together at a molecular level when the two halves are pressed into contact. As the solvent evaporates and the plastic re-hardens, the two pieces become one continuous sphere.
Once the solvent has dried and the bond is solid, the protruding flanges are trimmed off using precision cutting dies that come close enough to shear the excess material without actually cutting into the ball wall. Any remaining flange material is then stripped away, leaving a clean seam line around the ball’s equator.
Sanding, Polishing, and Coating
After trimming, the seam area is sanded smooth so the ball’s surface is as uniform as possible. The entire ball is then polished to create a consistent matte finish. This surface texture matters more than you might expect. It affects how the ball grips the rubber on a player’s paddle, which directly influences spin and control.
The balls are coated, printed with the manufacturer’s logo and markings, and given their final color. Competition balls are white or orange. The coating must be even enough that it doesn’t create weight imbalances on one side of the ball.
Quality Testing and Star Ratings
Not every ball that comes off the production line is equal, and the star rating system (one, two, or three stars) reflects how tightly each ball meets international standards. The differences come down to testing, not fundamentally different manufacturing processes.
Three-star balls are the top tier, approved for international competition. Each one is individually tested against strict tolerances set by the ITTF: weight must fall between 2.67 and 2.77 grams, diameter must be between 40.00 and 40.60 millimeters, and the ball must be perfectly round. Bounce testing requires that all balls rebound between 240 and 260 millimeters when dropped from a height of 305 millimeters onto a standard steel plate. Any ball that falls outside these windows is immediately rejected from the three-star category.
One-star balls are produced with less stringent quality controls and accept greater tolerances in dimensions and weight. They may have slight irregularities in shape or balance that wouldn’t pass three-star inspection, but they’re perfectly fine for casual play. Two-star balls sit in the middle, offering better consistency than one-star and often used for club training and local tournaments. In practice, the balls that fail three-star testing often get downgraded and sold as lower-tier products rather than being discarded.
Why Precision Matters This Much
A ping pong ball weighs less than three grams and travels at speeds that can exceed 60 miles per hour in competitive play. At those speeds, even tiny variations in roundness or weight distribution change how the ball curves through the air and bounces off the table. A ball that’s slightly heavier on one side will wobble. One that’s slightly out of round will bounce unpredictably.
This is why the manufacturing tolerances are so tight for a product that costs very little per unit. The ITTF’s specifications allow just 0.6 millimeters of variation in diameter and 0.1 grams in weight. For a ball this light, that 0.1-gram window represents roughly a 4% range, meaning manufacturers need precise control at every stage, from the thickness of the initial plastic sheet to the amount of solvent applied at the seam to the evenness of the final coating.