The bat: dimensions, composition and minimum wood
The ITTF — International Table Tennis Federation — devotes a short article of its rules to defining what counts as a legal bat in competition. It is short, but not trivial: what that article permits and prohibits ends up determining the shape of everything on the market.
The first thing that surprises a player reading the rule is what it does not regulate. The bat may have whatever shape, size and weight the player wants. There is no maximum head dimension, no standard handle length, no minimum or maximum weight. The typical dimensions described in 1.5 — a head of 156 to 160 mm, a handle of 9 or 10 cm, an assembled weight between 170 and 200 g — are conventions of the market and of human ergonomics, not regulatory impositions.
What the rules do require is that the striking surface be flat and rigid. Flat rules out curved or spoon-shaped bats; rigid rules out materials that deform as a whole on impact. The double condition closes the door on inventions that were patented in the past — bats with internal springs, with articulated surfaces, with exotic geometries — which the rule expels with a single stroke.
The other figure the player should retain is the one on composition: at least 85% of the thickness of the blade must be natural wood. The rules permit reinforcing the plies with fibrous materials — carbon, aramid, zylon, glass, arylate — but restrict their presence to a maximum of 7.5% of the total thickness or 0.35 mm per reinforcing ply, whichever is smaller. That restriction shapes the whole family of composite blades covered in chapter 10: ALC, ZLC and SZLC constructions are not arbitrary, they are solutions designed to fit within that margin. The federation wanted to preserve the character of the bat as a mostly wooden object, accepting that modern fibres are useful without allowing them to displace the historic material of the sport.
A final point affecting visible composition: the two faces of the bat, if they carry rubber, must be of different colours. The chromatic detail and its recent evolution are covered in 3.3.
The rules on the bat are, then, generous in the geometric — shape, size and weight free — and strict in the structural — flat, rigid, mostly wood. Knowing that asymmetry saves two confusions: that of the player who believes they must conform to dimensions that do not exist, and that of the player who believes a bat can be made of any material.