I really don't wanna go
@brokenball on these tests, but...
Just a few things to note: they use a 500g??? metal cube for the grip tests. That is not a plastic ball mostly because it is not plastic and not a ball. I have seen rubbers made for plastic ball act like an ice skate ring with the old caoutchouc ball. How each rubber acts with metal??? I don't know but not a good test if we play with plastic balls and not metal cubes.
It is true that it does not reflect "gameplay", since we are having a weight with the touching surface being metal, but at least it is comparable. What should they do ? Use a ball whose properties may change over time ? There are a good amount of difference between different brands of balls already, so trying to measure it with a "real" ball is more difficult and more error prone. Of course due to the difference between metal and plastic we can not transfer the results one to one to gameplay, but with metal being more smooth than a plastic ball we can see a kind of "worst case" scenario of the grip. I would guess that a tabletennis ball of the same mass/weight like the metal cube with the same surface touching the rubber would give even "stronger" grip values/measurements. In the summary list there are a few examples of rubbers that seem to grip metal not that well, even though we know that they grip the ball very well.
Their bounce test is conducted by dropping the ball from 50cm which is fine, but the rubber is held down with paper clips and the rubbers are not glued. I would be very cautious even if I glued to rubbers to pass judgment, but with paper clips... come on... The level of air pocket between the contraption and the rubber is random hence the bounce test might be flawed.
I would give them the benefit of the doubt, since they do not only do one or two bounce tests. In your description you make it sound like they fixate the rubber with paper clips, which is not correct. The rubber is placed on a surface with a wooden frame on top, which then is fixated with those clips. This means the ought to be a somehow even pressure on border of the rubber. Yes, there can be air bubbles beneath the rubber, but if they do it the same way for each rubber and use several measurements and not only one, then it should be comparable enough.
Softer rubbers should have more grip on this test since the 500g cube will compress the rubber more and have more of a ledge (lip?) that the cube needs to jump over. They measure the grip when the cube jumps so... Again use a plastic ball or something plastic with rounded corners.
Yes, that can definitely be true. On the other hand we should think about if that would really be the issue here and how much a 500g weight would sink in on a 55° sponge vs a 40° sponge. It might very well be that 500g is enough to indent the topsheet to the maximum already for hard sponges, which would make the test more comparable.
From the same hardness the thicker sponge will be softer.
@brokenball has been yapping about this for ages, it's boring by now but true.
Nobody disputes that and that is why they offer the reading of the sponge thickness and the topsheet thickness, so you can compare these. If one can make out the probable changes in measurements by the measured sponge thickness differences is very debatable, but you can at least try to compare rubbers that have similar sponge and topsheet thicknesses.
The hardness test I don't like but I hate every manufacturer's in this regard. They absolutely should make a tip that is the same as a table tennis ball and then test. Using a pointed tip is nonrepresentative for table tennis.
I agree, but as long as we dont have anything like that it is just wishful thinking.
For me it all boils down to "do i trust somebody to estimate the properties of a rubber by jugling the ball with it and playing a game or two while basically creating hundreds or thousands of unique situations (on how they hit the ball and how fast it is incoming with different trajectories) or do i trust somebody that put a little thought into testing a rubber and might it the "most scientific" we have on offer.
For me it is clear that i trust repeatable tests way more than somebody playing a game and in worst case trying to compare that with past experiences with different rubbers (on different humidity locations, different blades, different physical shape).
As of yet, i have not found a big difference in my own testing of rubbers. I am yet to find a rubber that is measured to have less than 22cm bounce height that is not feeling very controlled on pushes and the short touch game.
The comparisons with glued rubbers did match the results of that table (in relation). Of course i do not exactly measure a ball bounce of 50cm but i can compare two rubbers on the same blade with the same height and for the rubbers like G-1, Hybrid MK, Hybrid MK Pro, PK50, Hurricane 3 Neo, NH3TB they all matched if compared to each other.
If i actually play a game with the rubber or do drills on the robot this can of course change drastically due to the different throws. A stroke that works for the PK50 to push short will create a sky high tower on the Hybrid MK. This is obviously out of the purview of the testing shown.
Like pointed out by
Archosaurus, sponges will behave like progressive springs that do not behave the same on all levels of impact.
One experience i have had is recently was using the Victas V22 double extra and trying to push really short. The readings of anatomic edge table would not indicate that it is very bouncy (like the Vega X for instance), but still i simply failed to properly push short with this rubbers. Do i now detest the findings of the table or do i simply acknowledge that it was probably me having gotten too accustomed to the PK50 sieger which is an order of magnitude less catapulty hence my technique (and lack of soft hand) failing me?
I challenge anybody with a robot or other method of somehow reliably create same shots to show that the Hybrid MK is worlds more controlled in the short game than the G-1 (taking the human element out of the equation).
I am pretty sure you can't.
They are in the same ballpark in that low power incoming ball scenario, so i have to guess that the MK hybrids throw might favour the pushing technique of the people that claim that the MK is way more controlled. This may all be true and nobody will detest that. Fitting your technique better does not change the measurable properties of the rubber though.
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