ITTF Technical Specifications for Inverted Rubber, Pimpled Rubber and Anti‑Spin Rubber

The International Table Tennis Federation (ITTF) sets strict physical parameter standards for racket covering materials to guarantee fairness in international table tennis competitions. Three main categories of rubber are defined: inverted rubber, pimpled rubber and anti‑spin rubber. All products must pass ITTF certification and appear on the authorised rubber list before being used in official ITTF-sanctioned tournaments.

1. Inverted Rubber (Pimples‑in Rubber)

Inverted rubber belongs to sandwich rubber. Its pimples face inward and attach to sponge, with a smooth outer hitting surface.

Total thickness: The full assembly (top sheet + sponge + adhesive) must not exceed 4.0 mm; the official tolerance upper limit is 4.05 mm. The rubber top sheet alone cannot exceed 2.0 mm.

Structure requirement: Must be fitted with cellular sponge. Bare inverted top sheet without sponge is not permitted for competition use.

Surface property: Matte finish, non-glossy. Kinetic friction coefficient with table tennis ball ≥0.50.

Colour rule: Matt black on one racket side; the opposite side must be a distinct bright colour approved by ITTF.

Material integrity: The covering must be continuous and uniform in thickness. No chemical or physical modifications to alter performance are allowed.

2. Pimpled Rubber (Pips‑out Rubber)

Pimpled rubber has pimples protruding outward. It is split into two types: ordinary pimpled rubber (OX, sponge-free) and sandwich pimpled rubber (with sponge).

Ordinary pimpled rubber (no sponge, OX)

Total thickness: Rubber sheet plus adhesive ≤ 2.0 mm, tolerance upper limit 2.05 mm. It is single-layer non-cellular rubber without foam sponge.

Pimple density: Evenly distributed pimples, 10 to 30 pimples per cm².

Pimple geometry: Pimples should have circular symmetry; the central axis must be perpendicular to the base layer.

Long pimples: pimple height ≥1.0 mm; aspect ratio (height / pimple top diameter) ≤1.10.

Short pimples: shorter height and smaller aspect ratio, still following the same density and symmetry rules.

Optional sponge version: When mounted as sandwich rubber with sponge, it falls under the 4.0 mm total thickness rule (including glue). OX pimple rubber may be used without sponge.

3. Anti‑Spin Rubber

Anti-spin rubber is a special variant of inverted sandwich rubber. It has a smooth outer surface but extremely low surface friction to neutralise incoming opponent spin.

Classification: Categorised as sandwich rubber (pimples inwards). Sponge is mandatory.

Total thickness: Top sheet + sponge + adhesive ≤ 4.0 mm (tolerance 4.05 mm). The top sheet thickness limit is 2.0 mm.

Friction characteristic: Designed for low friction, still subject to ITTF friction and matte surface inspection.

Other rules: Same colour, surface gloss, material continuity and ITTF authorisation requirements as regular inverted rubber. It cannot be chemically treated to further reduce friction after production.

General Common ITTF Rules

All rubber coverings must extend up to but not beyond the edge of the blade; only the handle/grip zone may remain uncovered.

No additives, oil, solvent or coating may be applied to modify rubber speed, spin or friction after factory production.

All racket coverings must obtain ITTF product certification and be listed in the ITTF Authorised Racket Coverings List (LARC). Uncertified rubber is banned in official matches.