There's been mention here of a Nexy blog post about Karis, so I looked on this forum for a Nexy blog. Could've sworn I've seen one in the past but can't find it now. Anyhow, I was pointed to the Nexy blog on another forum:http://mytabletennis.net/forum/forum_po ... ners-diary
I will quote the entry on Karis here, because, I think, few people will have seen it in the other place (it's worth a look, lots of stuff about blades):
What Makes Karis Different?
It’s been a while since I promised to write more about Karis. In order to explain more details about this rubber, I will first summarize what I previously wrote:
The history of soft rubber development met a big obstacle when the ITTF initiated the “speed glue” ban. Speed gluing relies on using a chemical to penetrate deep into the sponge to soften the material and add elasticity, which increases speed and spin. After the speed glue ban policy, many brands had to find a new way to enhance rubbers.
So, we could find two different ways among rubber brands. German rubber manufacturers began making high-tension rubbers that focused on artificially expanding the sponge, such as Nimbus and Sinus.
Japanese manufactures like Butterfly turned away from high-tension rubbers like Bryce into a new line of bubbled sponge rubbers. Tenergy adopted a new sponge that has air capsules inside. This air capsule worked as a spring that helped to keep the elasticity of the sponge. But many high-tension rubbers have a problem with unexpected ball movement against powerful shots. High-tension rubbers tended to become solid and they could lose the power to catapult the strong shot by top players. Therefore, many high level players moved away from European brands to Butterfly’s Tenergy05. Note: Tenergy is not a pure synthetic rubber product — it began using a boosting technology from the beginning.
Sometime later, ESN started to produce bubbled sponges as Butterfly did, and Genius of Tibhar became the first release. These bubbled sponge rubbers could work well with hard sponge rubbers, and ESN released many hard rubbers in order to compete with Tenergy.
But, like the high-tension rubbers, those hard rubbers had stability problems, e.g., unexpected ball movement.
When we adopt a hard topsheet to drive the ball, the rubber tries to hold on as long as possible (upward movement), but in the same time, a hard sponge tries to expel the ball quickly (returning movement). Those two different directions could confuse the final ball movement. So, players experience unexpected ball motion when we play with a hard topsheet + hard sponge rubbers. MX-P is a good example for this phenomenon.
During this period of rubber development, there was another big change in table tennis. The ITTF introduced the plastic ball, which was heavier and players could not generate as much spin as they did before with celluloid balls. So, many brands tried to make a more powerful rubber, which resulted in a hard topsheet assembled on a hard sponge. But they could not solve the strange feedback problem. So, ESN switched from a hard top sheet + hard sponge to softer topsheets. A good example of this is Tibhar’s 5Q and Quantum.
At the same time, Butterfly also tried to minimize this problem. Their Tenergy05 became softer than before, and they also released many other soft version rubbers, such as Tenergy 80, 64, and 25.
To sum up, the trend in top quality rubber configuration became a softer topsheet with a hard sponge. But I thought that hard topsheet supported by hard sponge rubbers were still more attractive to many players, even though they sometimes had issues with odd rubber feedback.
I thought about how I could make a new NEXY rubber that featured a hard topsheet + hard sponge without that unexpected ball movement. This is the key reason why Karis is different from all the trendy rubbers.
Karis did not try to solve this problem by only changing the chemical recipe. We also tried to test shorter columns in order to make the topsheet move in sync with the sponge. As previously explained, we tried to eliminate the problem of the topsheet not moving in harmony with the sponge. So, by cutting the column shorter, we could build-up a rubber that moves harmoniously with the sponge.
I am revealing this secret because I know that other brands cannot easily find the optimum length with optimum materials. When we first tested several other rubbers with this shorter column structure, we discovered that many rubbers became extremely dull. It’s not easy to find the good composition with this shorter column topsheet. I will welcome other brands to use my idea, but they will have to pay the fee as I spent two whole years on this new rubber.
That’s it! Karis does not have the inherent problems that other top quality hard topsheet rubbers often do. You can trust this rubber. You will feel that this rubber shows only one strong movement, and you will like this direct motion through the whole depth.
We are sure that our rubber will be good, but it will take some time for you to get accustomed to this direct feeling. Give it a try, and you will have no more stress from the instability of powerful rubbers.
Karis will be released during the final week of October, and the price will be $50 USD all over the world. Spread the word because this is a quite a revolutionary change in rubber history, and you will see that one small Korean brand broke through a big wall that many other global brands could not overcome.
Thank you for reading this.
There's a lot of information in there about rubbers in general and about Karis in particular.
1) About Tenergy and Tensors.
He talks about "air capsules" in Tenergy, I interpret this to mean that the sponge has enclosed air bubbles which don't allow air to flow through pore spaces. This appears as "large pore sponge", - the "pores" are actually bubbles which don't touch each other, as opposed to the sort of pores you find in a bath sponge, which allow air to flow from one pore to another. I suppose it would work just as well if these pores were a tenth the size, but perhaps it is easier to control during manufacture if the pores (and pore walls) were large. Apparently this was a new concept that came in with Tenergy, but ESN has come out with their version of it, so the difference between older Tensors and newer ones is this "air capsule" technology. You can see it here in the Rasant sponge.
In contrast, here's 729 FX with the large pore sponge:
There are a LOT more pores, I wonder if the "capsules" are closed off..
2) Hard rubbers and "loss of control"
He says that with hard topsheet/sponge:
When we adopt a hard topsheet to drive the ball, the rubber tries to hold on as long as possible (upward movement),
(I must admit, this part mystifies me.)
but in the same time, a hard sponge tries to expel the ball quickly (returning movement). Those two different directions could confuse the final ball movement. So, players experience unexpected ball motion when we play with a hard topsheet + hard sponge rubbers. MX-P is a good example for this phenomenon.
you lose control with hard shots. Perhaps not the same thing as shots "bottoming out" (that's a problem with soft sponge, isn't it?). Karis is supposed to alleviate this problem.
I suspect I'm not able to hit the ball hard enough to even have this problem to begin with..
3) As mention here and elsewhere, the trick is ultra short pips. Makes you wonder what we would've had if they hadn't mandated pips under "inverted" rubber in 1959. What would Karis play like with NO pips? Just a smooth topsheet. One thing's for sure - if this is truly revolutionary we'll see other manufacturers adopt the concept. We'll see ultra-short pips under inverted topsheets from ESN, and from the Chinese. Unless Nexy helps them (i.e. reveals the secret formula rubber, etc.) they won't be obligated to pay licensing, and we'll see a variety of these appear. Some will work better than others. If they can shrink the pips while keeping the topsheet thickness the same we'll probably see thicker "max" sponge as well (maybe 2.4mm? 2.5mm?). I'll bet ESN's looking into this already, so is DHS.