Thursday, October 24, 2013

The New Poly Ball is Coming . . . Maybe

In March 2012, the ITTF Board of Directors voted to pass the following resolution, proposed by the Executive Committee and the Athletes' Commission:

"That the new Poly balls (non-celluloid material) be used at ITTF events as of 1 July 2014. The Executive Committee may allow the use of the Poly balls, in exceptional cases, in the period between the 2014 World Championships and 1 July 2014."

Half of a celluloid ball, formed by pressing a disc into a
hemisphere. It will be trimmed, glued with another half,
and polished. Image taken from the Nittaku ball video.

Celluloid is one of the first industrial plastics, dating to the 1800s. "Poly" refers to other kinds of plastics such as polyethylene. The rules of table tennis permit the use of any kind of plastic ball, so there's no rule change required for the adoption of a new ball material. This resolution just designates a particular type of ball for a few dozen elite events.

From one perspective this is not much of a change. The direct scope only extends to ITTF events: World Title Competitions and ITTF Sanctioned tournaments, which includes the ITTF World Tour, ITTF Junior Circuit, and continental events. The ITTF already specifies a particular ball for these tournaments. For example, all World Tour events must use the DHS ball, while Junior Circuit events must use the Butterfly ball. So this resolution is in a similar vein in that it designates a ball to use, but in this case it's by material type, not brand.

But even though this resolution is directed at specific elite events, the game played by the pros is also played by aspiring pros; likewise, aspiring pros play with dedicated amateurs and weekend hacks. Even novice players want to play the same game as the professionals. A change in equipment at the top has broad effects.

Each celluloid ball is checked by hand and sent through
a gauntlet of mechanical testing devices before it gets
its final grade. Image taken from the Nittaku ball video.
At the time of this writing, every ball approved by the ITTF is made of celluloid. In the manufacturing process, celluloid is largely composed of nitrocellulose, a highly flammable material. Celluloid is not the easiest material to work with, and most historical uses of celluloid transitioned to newer plastic materials long ago, with the major exceptions being as decorative components in things like pens and musical instruments . . . and table tennis balls. If and when we stop using celluloid in table tennis, we'll be one of the last entities to do so.

Poly balls were briefly used in competitive table tennis a few decades ago, so in that sense it's not new. Poly table tennis balls are also readily available as recreational toys, but not built to the standards required for official competition. The forthcoming poly balls are expected to meet ITTF requirements and behave more like celluloid balls than older versions.

Some players and coaches have been able to acquire prototype poly balls for testing purposes. Reviews of those prototypes have been mixed. However until a brand of ball is fully tested by the ITTF in the approval process, nobody can legitimately claim that they have seen a final production set of approved balls. And nobody can truly say they know how the new ball will behave.

Personally, I would like the playing properties of the poly ball to be similar to the celluloid ball in feel, but improved in technical aspects such as roundness, durability, and regularity of hardness and bounce. I am hopeful that the use of modern materials and manufacturing processes can help lead to those improvements. However with the change in material there will probably be differences seen during play, and the more differences there are, the more time players will need to adjust to the changes.

Domestic competition does not fall under ITTF jurisdiction, and USATT tournaments could conceivably continue to use celluloid balls indefinitely, as long as there is an available supply of balls. Anyways, until there is actually an approved ball, and until that ball is available for purchase, we will continue to use celluloid balls by default.

How players, tournament directors, and USATT deal with the poly ball will depend on when it arrives, and how it performs. The fate of the poly and the celluloid ball may ultimately be decided by market forces and manufacturer decisions.

The 2013 USATT Annual Assembly will be held in Las Vegas at 7pm on Wednesday, December 18th, and all USATT members are welcome to attend. The complete program has not been determined, but I will be available to field questions about the ball or anything else.


  1. The nitrocellulose used to make table tennis balls is not the same as "gun cotton." Table tennis balls use a form,pyroxylin, that has less nitrogen content and is not an explosive.

    While Kagin is correct that there have been no rules changes, decreeing the use of a poly ball in 2014 is not the only change that the ITTF has made. They've also amended the T3 ball tolerances giving a new set of tolerances that is different for the poly ball than for they are for the celluloid ball. Current celluloid balls are typically about 39.7mm in diameter and the poly ball tolerances will likely result in balls 40.1 to 40.2 mm in diameter. Given that the poly balls have the same weight limits, it is very likely that the new poly ball will have aerodynamic differences that will be discernible. It will be slower, harder to spin, and less likely to maintain spin compared to the current celluloid ball.

    It's true that reviews have been mixed. But it is also true that reviews have been generally negative. And yes, we cannot know precisely how new balls will perform. But the implications of the changes in tolerances should have on some aspects of the ball's performance and the fact that prototype performance jibes with those implications means we are far from being in the dark on what to expect.

  2. Thanks for the correction about pyroxylin.

    I'm not happy about the tolerances.

  3. I have personally tested several dozens of both seamless and seamed poly balls. The seamless poly ball represented a more drastic departure from traditional celluloid ball performance. It had a very smooth surface, was noticeably slower and less spinny, and were consistently between 40.20-40.25 mm. Slow heavy underspin "stopped" and bounced a little higher than celluloid balls.

    I believe it will provide some advantages to underspin players as choppers can both float a slow heavy underspin chop that hangs over the table and drive chop a more traditional bouncing chop that continues off the end of the table. The difference between these two bounces is quit dramatic IMO, and makes it more difficult for attackers to groove into a consistent and strong attack.

    I also think it will be good for long pips close to table blockers who can soft block back short underspin returns off attackers' heavy topspin loops, making it difficult for the attacker to continue their attack. Topspin play with the seamless poly balls was similar to celluloid play.

    Seamed poly balls, on the other hand, were much more similar to celluloid play in bounce, speed, and amount of spin. I judged the speed and spin to be between that offered by celluloid balls and the seamless poly balls. They also had a much rougher surface than the seamless ones. However, many of these balls displayed significant dissimilarities in the diameter as measured at the "equator" and at the "poles". The worst had almost .50 mm difference in diameters between equator and poles.

    But when I found one that had similar diameters, the ball played relatively like a celluloid ball. I think both batches of balls I tested were of the "first draft" variety. I think with continued attention and research into the manufacturing process, both balls can become as consistent as celluloid balls.

    My personal preference is the seamed poly balls as I notice only small differences as compared to celluloid. But I really think that the seamless poly ball will be better for the sport--it'll make backspin play more effective and slow the speed and spin down to the level it was 30+ years ago before speed glue, tensor sponges, pre-tensioned topsheets, and tuners. I think such a move will encourage more variety of styles, more patient play, and allow audiences to more easily follow the play.