Modern billiard balls are made of phenolic resin, a hard plastic derived from petroleum. This has been the standard material for decades, replacing a long line of predecessors that included ivory, bone, and early plastics. The specific type, phenol-formaldehyde resin, gives the balls their characteristic click, consistent bounce, and resistance to chipping.
Phenolic Resin: The Modern Standard
Phenolic resin is created by combining phenol and formaldehyde under heat and pressure, producing an extremely hard, dense material. It resists heat, absorbs very little moisture, and maintains its shape over thousands of impacts. These properties matter because billiard balls endure serious punishment. A cue ball can accelerate from zero to over 30 km/h almost instantaneously, and friction at the contact point between ball and cloth can spike above 250°C (482°F) in a fraction of a second.
The dominant manufacturer, Aramith (based in Belgium), uses a thirteen-step production process that takes up to 23 days per set. This includes casting the resin, curing it through multiple hardening stages, and finishing with precision grinding and polishing. High-end Aramith balls receive an additional vitrification layer, essentially a glass-like surface coating that makes them exceptionally wear-resistant. This surface is what gives professional-grade balls their translucent depth and a polish that holds up over years of play.
Budget Balls Use Different Plastics
Not every billiard ball on the market is phenolic resin. Cheaper sets are made from polyester or acrylic, which cost significantly less but behave differently on the table. Polyester balls wear down faster, are more prone to chipping, and don’t transfer energy as consistently during impacts. Over time, they develop flat spots and surface roughness that affect how they roll and how much they chew up your table cloth.
For casual home use, polyester sets work fine and keep the price of a pool table setup reasonable. But for league play, tournaments, or anyone who plays regularly, phenolic resin is the clear choice. The balls last longer, play more predictably, and are gentler on cloth because their harder, smoother surface creates less damaging friction.
Size and Weight Vary by Game
Billiard balls aren’t one-size-fits-all. The dimensions depend on which game you’re playing:
- American pool balls: 2 1/4 inches (57.15 mm) in diameter, weighing between 156 and 170 grams
- Snooker balls: 2 1/16 inches (52.5 mm)
- English pool balls: 2 inches (50.8 mm)
- Carom billiard balls: approximately 61.5 mm, the largest of the group
Professional specifications are tight. The World Pool-Billiard Association allows a tolerance of only +/- 0.05 mm on diameter for competition balls. That’s roughly the thickness of a human hair. Weight consistency across a set matters too, because even small differences between balls change how they behave after collisions.
From Ivory to Plastic: A Brief History
For most of billiards’ history, the best balls were carved from elephant ivory. Ivory had the right density, a pleasant sound on impact, and could be polished to a smooth finish. It was also wildly expensive, inconsistent from ball to ball (since tusks aren’t uniform), and required the slaughter of elephants on an industrial scale. By the mid-1800s, the billiard industry was actively searching for alternatives.
The first successful substitute was celluloid, an early plastic made from nitrocellulose. Celluloid balls were lighter and more uniform than ivory, and manufacturers reinforced them with bone dust to improve their weight and feel. These composite balls represented a genuine leap forward. Players noticed that reinforced celluloid sets were consistent enough in weight that pre-match weighing, which had been standard practice with ivory, became unnecessary.
Celluloid had its own problems, though. It was flammable and degraded over time. Polyester resins eventually replaced it, and phenolic resin became the gold standard by the mid-20th century. Today, every professional tournament worldwide uses phenolic resin balls.
Why the Material Matters for Play
The material a billiard ball is made from directly affects how it plays. Phenolic resin’s density means energy transfers efficiently between balls during collisions, giving you predictable angles and speed. Its hardness means the ball doesn’t deform on impact, even slightly, which would absorb energy and make shots less responsive. And its surface holds a polish for years, which keeps friction consistent and protects your cloth from the burn marks that rougher, softer balls create more easily.
Those burn marks, the small white spots you sometimes see on pool table cloth, happen because the friction between ball and fabric generates enough heat to singe the fibers. Higher-quality balls with smoother, harder surfaces reduce this effect, though no ball eliminates it entirely on hard shots. This is one of the less obvious reasons that serious players invest in premium ball sets: they’re not just protecting their game, they’re protecting a cloth that can cost hundreds of dollars to replace.