The Racket - Rules and Ways to Exploit Them

As you might have seen in the Olympics lately, the players receive their rackets from the referees before a game starts. This because the rackets are checked for illegal material, substances, and so on.

The following are the regulations that every racket needs to follow (2011/2012)

1. The racket may be of any size, shape or weight but the blade shall be flat and rigid. 
2. At least 85% of the blade by thickness shall be of natural wood; an adhesive layer within the blade may be reinforced with fibrous material such as carbon fibre, glass fibre or compressed paper, but shall not be thicker than 7.5% of the total thickness or 0.35mm, whichever is the smaller. 
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 2.0mm, or sandwich rubber, with pimples inwards or outwards, having a total thickness including adhesive of not more than 4.0mm. 
4. 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 cm2 and not more than 30 per cm2. 
5. 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 2.0mm. 
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.
7. The blade, any layer within the blade and any layer of covering material or adhesive on a side used for striking the ball shall be continuous and of even thickness. 
8. The surface of the covering material on a side of the blade, or of a side of the blade if it is left uncovered, shall be matt, bright red on one side and black on the other. 
9. The racket covering shall be used without any physical, chemical or other treatment. 
10. Slight deviations from continuity of surface or uniformity of colour due to accidental damage or wear may be allowed provided that they do not significantly change the characteristics of the surface. 
11. Before the start of a match and whenever he or she changes his or her racket during a match a player shall show his or her opponent and the umpire the racket he or she is about to use and shall allow them to examine it. 

(Source)

Since the rules in table tennis aren't always very strict, there are some things that should be pointed out in this list of regulations.

The material does not necessarily need to be wood

The regulations clearly says that the areas that the ball will never hit can be covered with any material. There is no rule that forbids the user to have whole handles made out of other materials than wood. Another thing that is not mentioned, is that blades made out of cork and bamboo - which is not wood - can be accepted as legal blades. I have also contacted the Swedish table tennis association (SBTF) about this, and they have confirmed that bamboo should be okay while cork is doubtful. Even though cork is tree bark, and bamboo is grass.

Because of these regulations, blade maker American Hinoki has made a blade completely out of cork and bamboo, and calls it the ITTF Rules Protest Blade.

The regulations can be exploited because of lack of precision

Some players who use penhold blades, don't use the backhand side of their blade to hit the ball. But they're still forced by the rules to wear a rubber on each side. Though, there is no rule specifying any minimal amount of rubber, - it just needs to cover the part of the blade where you don't keep your fingers. But a Japanese penholder keeps his fingers over half the blade, - therefore you often see them have one rubber that covers only about half the blade. This means that their blades get significantly lighter than if the rubber covered the whole surface. They can also cut off a little extra weight by making a nice looking curve - as long as all text on the rubber shows (so the referees can identify it as approved material).

Since there is no rule saying that the handles need to be made out of wood, it should be okay using other materials. Most Japanese penhold blades have cork as handle - and since no rule defines what a handle should be shaped like, they often only have the cork on one side of the blade. In the end, Japanese penhold blades can have a very low weight, which brings higher speed.

The rubbers can be a little too big

The rubbers are supposed to reach the edges of the blade, but aren't supposed to stick out further than necessary. Still, you see professionals play with rubbers sticking out several millimeters. (Maybe enough to save a ball every now and then?) Referees have never seemed to mind this, so it can be utilized. To make it less noticeable, edge tape can be used.

Conclusion

Experiment! Use the loopholes to find the best possible assembly for you. Until the ITTF gets more specific!