Modern, high quality snooker balls are made from phenolic resin, a synthetic polymer formed by the reaction of phenol, a.k.a. carbolic acid, an aromatic organic compound derived from benzene, and formaldehyde, a colourless, but highly reactive, gas derived from methane. Phenolic resin is a strong, durable material, offering high abrasion impact and shearing resistance, and can easily be polished to the required lustre. Snooker balls are made by pouring liquid phenolic resin, pre-coloured at the production stage, into moulds without the application of pressure – or, in other words, by casting – followed by thermal curing, at temperatures up to 180°C, to stabilise the material and polishing.
The standard diameter of a snooker ball is 2.07″ and high-end grade snooker balls are manufactured within a tolerance of +/- 0.003″, which is less than than the +/- 0.002″ specified in Section 1, 2(b) of ‘The Official Rules of the Games of Snooker and English Billiards’. Furthermore, the tolerance of roundness, or sphericity, which determines balance and rolling characteristics, of such balls is just +/- 0.0012″. Inevitably, snooker balls vary in weight, albeit only slightly, such that a maximum tolerance of 0.11oz, between the heaviest and lightest ball in a set is permitted. Again, high-end grade snooker balls are matched into sets with a maximum tolerance of 0.04oz per set.