Definition: According to Law 2.4.3.1 of the Laws of Table Tennis, 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 per square cm and not more than 30 per square cm.
The rubber has pimples on one side, and is smooth on the other. The smooth side is glued directly onto the blade, so that the pimples are used to hit the ball.
Ordinary pimpled rubber is also commonly known as hardbat rubber, since there is no sponge underneath the layer of rubber. It is also sometimes known as pips out or pimples out rubber, although technically this term would also include rubbers that have a sponge layer underneath the rubber.
It is also sometimes known as orthodox rubber, since ordinary pimpled rubber was the first type of rubber sheets used in table tennis.
Also Known As: hardbat rubber, pimples out rubber, pips out rubber, orthodox rubber