The Truth About Rubber Hardness
Even though players often rely on the manufacturer’s stated hardness when choosing rubber, the truth is this matter is actually a bit complicated.
Today we’re mainly talking about tensor (outer) rubbers, especially the German rubbers made by ESN.
The same stated hardness feels different to different players
A rubber is made by combining a topsheet and a sponge. The hardness the manufacturer states is only the sponge hardness. In reality, the thickness of the topsheet, the shape and size of the pimples, and differences in manufacturing methods all affect the overall hardness.
Within Butterfly’s lineup, even though both are marked 36 degrees, the contact feel of T64 and T05 and the hardness we actually perceive are different. In general play, T64 feels much softer than T05.
If the pimples themselves are fine and long and the top of the topsheet is thin, you don’t need much force to feel the deformation, and the hitting feel skews soft. This kind of rubber is very easy to get on the table and can produce a “light and quick” feel, like Butterfly’s Bryce Highspeed or Donic’s F2. Very easy to play, but because the surface is thin, it also cracks easily.
If the pimples themselves are short and thick and the surface is thicker, you’ll feel a harder touch in use, like DHS’s Hurricane series, especially Hurricane 2 and Skyline 2. This kind tends to produce strong spin. If the rubber compound itself is high in density, we feel it as “hard,” and it’s generally on the heavy side. Then, the proportions of natural and synthetic rubber in the compound, plus the addition of various chemical compounds, all affect how soft or hard the hitting feel is.
So even with the same sponge hardness, we might still perceive that, say, the red version of a certain rubber is harder than the black, or the blue grips the ball more than the red, and so on.
Rubbers keep getting harder
There was a time when a 47.5-degree German rubber could serve as a forehand rubber; now it’s often used on the backhand instead. Anything above 50 degrees has become mainstream.
In the new plastic-ball era, rubbers really have been getting harder. The old celluloid balls were relatively soft themselves and deformed easily. If you raised the rubber’s hardness without raising your own power, the ball’s speed and spin didn’t improve much; instead, your control over the ball got worse.
Now in the plastic-ball era, the ball deforms less than before. Especially when people play seamed balls, they often feel heavier than seamless ones. In that case, the old rubber hardness can’t quite drive the ball anymore, which forces you to raise the rubber’s hardness.
In the European market, 47.5 degrees used to be the most popular, but now people prefer 50 to 52.5 degrees. That said, even for pros, an increase in hardness takes getting used to. Generally, for beginner-to-intermediate players, under 50 degrees is plenty.
And once hardness goes up across the board, ball quality improves too, but the weight increases and it gets harder to handle. Take Donic C1: although it plays well and has the flavor of a boosted, energy-infused Hurricane, it’s brutal on the wrist. T05 Hard has astonishing ball quality, but it’s also hard and heavy, putting your multi-ball rallying ability to the test.
I still lean toward recommending that everyone use a hardness that feels comfortable to swing. It may seem like you’re not maximizing power, but you can raise your swing tempo, which indirectly boosts both speed and margin for error.
Of course, some brands are making an effort. Take Stiga’s DNA Platinum series: some have raised the hardness while continually trying to “reduce the weight.”
The influence of swing speed
The harder and heavier the rubber, the more it requires a player to have enough ability and skill to control it. Generally, for top players, the rubbers brands make specially for them (like Butterfly’s white-shell specials, and the hardness bumps Tibhar and Victas apply to their pro players’ rubbers) are two or three grams heavier than the market versions.
Harder and heavier means more ferocious ball quality, but it’s also harder to master. A little softer and lighter lowers the error rate and gives you a better arc. For example, the backhand rubber Ma Long uses is softer than many national-team players’, and he places special emphasis on the importance of a “good arc.”
And a softer, lighter rubber lets you swing faster too. So this really comes down to your individual feel. There’s no one-size-fits-all answer.
The influence of temperature and humidity
Generally, a blade that’s been played a lot or has gotten damp will feel like it’s gone “mealy”: no longer crisp, with reduced elasticity. So drying it out from time to time is necessary (the simplest method being to put a packet of desiccant in your bag).
Natural rubber is affected too. That’s why rubber-production workshops generally keep their temperature and humidity well controlled.
And even a rubber that’s soft by nature will feel hard when the weather is too cold. This is completely normal. With different environments, we really can feel the difference in a rubber’s hardness.