I've recently been experimenting with multi-surface bats and I have some questions about the legality of a bat with one side regular rubber and the other having just the sponge layer with no rubber covering. I'd be interested in hearing your opinion as to the legality of this surface or if you could suggest some kind of alternative.
Tyler
No, it is not legal to use sponge without a topsheet on a table tennis racket. If sponge is used, it must be covered with a topsheet made of ordinary pimpled rubber with pimples inwards or outwards.
According to the Laws of Table Tennis:
2.4.3 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 2mm, or sandwich rubber, with pimples inwards or outwards, having a total thickness including adhesive of not more than 4mm.
2.4.3.1 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 per sq. cm and not more than 30 per sq. cm.
2.4.3.2 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 2mm.
So as you can see, there is no provision for legally using a racket that has sponge only on one or both sides. If sponge is used, it must be covered with a topsheet of ordinary pimpled rubber that is not more than 2mm thick, and the total thickness of both sponge and rubber cannot be more than 4mm.
As far as alternatives go, it really depends on the grippiness of the sponge layer. From my memory of playing with just sponge for fun, it does have a little grip, but it doesn't really feel like normal rubber. Perhaps a sheet of something like Sriver on a very thin sponge like 0.5mm might do the trick?
