This article is from the Table Tennis (Ping Pong) FAQ, by firstname.lastname@example.org with numerous contributions by others.
4.1 The racket may be of any size, shape or weight.
4.2 The blade shall be continuous, of even thickness, flat and rigid.
4.2.1 At least 85% of the blade by thickness shall be of natural wood.
4.2.2 An adhesive layer within the blade may be reinforced with fibrous
material such as carbon fiber, glass fiber or compressed paper, but
shall not be thicker than 7.5% of the total thickness or 0.35 mm,
whichever is the smaller.
4.3 The visible surface of each side of the blade, whether used for
striking the ball or not, shall be uniformly dark colored and matt.
Any trimming or binding around the edge of the blade shall not be
either wholly or partly white or brightly reflecting.
4.4 A side of the blade used for striking the ball shall be covered
with either ordinary pimpled rubber with pimples outwards having a
total thickness including adhesive of not more than 2 mm or
sandwich rubber with pimples inwards or outwards having a total
thickness including adhesive of not more than 4 mm.
4.4.1 only adhesives that have been approved by the ittf for this purpose
may be used to attach the rubber to the blade.
4.4.2 after august 1, 1995, no adhesive that uses any solvent may be used
to attach the rubber to the blade.
4.5.1 "ordinary pimpled rubber" is a single layer of non-cellular rubber,
natural or synthetic, with pimples evenly distributed over its
surface at a density of not less than 10 sq cm and not more than
50 sq cm.
4.5.2 "sandwich rubber" is a single layer of cellular rubber covered with
a single outer layer of ordinary pimpled rubber, the thickness of
the pimpled rubber not being more than 2 mm.
4.6 the covering material shall extend up to but not beyond the limits
of the blade, except that the part nearest the handle and gripped
by the fingers may be left uncovered or covered with any material
and may be considered part of the handle.
4.7 the blade, any layer within the blade and any layer of covering
material or adhesive shall be continuous and of even thickness.
4.8 the two surfaces of the racket blade shall be of clearly different
colors, namely black and bright red, as defined in the ittf
4.9 it is the responsibility of the player to ensure that the racket
covering can be identified as an authorized brand and type and that
the colors of the two surfaces of the blade are clearly
distinguishable under normal playing conditions.
4.10 subject to the requirements of 4.3 a side of the blade not intended
for striking the ball may be painted or covered with any material,
but if a player strikes the ball in play with a side of the blade
whose surface does not comply with the requirements of 4.4 - 4.9 he
shall lose a point.
4.11 slight deviations from uniformity or continuity of covering due to
fading, wear or accidental damage, may be ignored provided they do
not significantly change the characteristics of the surface.
4.12 at the start of a match and whenever he changes his racket during a
match, a player shall show his opponent and the umpire the racket
he is about to use and shall allow them to examine it.