Sponge hardness on rubbers

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Hey.
I'm somewhat new to shopping for rubbers for my blade and getting a bit confused by the sponge hardness differences.
Stiga f.ex says its medium hardness is around 47,5 degree, but butterfly's 09C f.ex is classified as a Hard rubber but is only 44 degree????
Anyone that can give me a quick lesson on this?
I'v used club-bought Joola rubbers until now, but looking at f.ex Stiga rubbers atm. Looking at H and M or M and S and I am confused. Looking at the Joola rubbers I'm using atm, Rhzym tech 47.5 and Rhyzm 42.5 are the sponge hardness comparable to Stiga?
Tnx :)
/Espen
 
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Hey.
I'm somewhat new to shopping for rubbers for my blade and getting a bit confused by the sponge hardness differences.
Stiga f.ex says its medium hardness is around 47,5 degree, but butterfly's 09C f.ex is classified as a Hard rubber but is only 44 degree????
Anyone that can give me a quick lesson on this?
I'v used club-bought Joola rubbers until now, but looking at f.ex Stiga rubbers atm. Looking at H and M or M and S and I am confused. Looking at the Joola rubbers I'm using atm, Rhzym tech 47.5 and Rhyzm 42.5 are the sponge hardness comparable to Stiga?
Tnx :)
/Espen
From my experience the Joola and Stiga rubbers hardness is comparable :)
 
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Hey.
I'm somewhat new to shopping for rubbers for my blade and getting a bit confused by the sponge hardness differences.
Stiga f.ex says its medium hardness is around 47,5 degree, but butterfly's 09C f.ex is classified as a Hard rubber but is only 44 degree????
Hardness is a personal preference. Some people like the feel of harder rubbers. There is a "Goldilocks" zone. The rubbers can be too hard or too soft. Also, the hardness of rubbers has nothing to do with how elastic it is.
Faster rubber will bel more elastic.
There are formulas for computing the speed after impact given the elasticity of the rubber. There is not such thing for the hardness of rubber. Again, some people prefer the feel of hard rubber and some like softer rubber.

Anyone that can give me a quick lesson on this?
I'v used club-bought Joola rubbers until now, but looking at f.ex Stiga rubbers atm. Looking at H and M or M and S and I am confused. Looking at the Joola rubbers I'm using atm, Rhzym tech 47.5 and Rhyzm 42.5 are the sponge hardness comparable to Stiga?
Tnx :)
/Espen
The rubbers in the range of 42-48, medium, are about right for most people. I wouldn't get too hung up on the hardness of rubbers. If you don't know what to buy then buy a medium rubber. Then the next time you can get something harder or softer.
 
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Also, the hardness of rubbers has nothing to do with how elastic it is.
Myth. Just because there is not a simple formula doesn't mean the two variables have no correlation.
 
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MEASURING UNIFICATION NEEDED URGENTLY.

The problem we encountered is that some manufactories using separated sponge in measuring, and some using a combination of sponge + topsheet.
We have now advised ITTF on the problem and proposed unification of the hardness measurements with all manufacturers.
 
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They use different scales. ESN, aka german rubbers like Donic, 47.5 is about 36 Butterfly and 37 DHS.

Even though Butterfly and DHS seem similar, they are a bit different.

Friendship 729 Battle Two 38 degrees rubber equally how hardness degrees of ESN rubber scales ?

Thank you sir.
Best regards,
 
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Speaking of sponge hardness, during the month of Dec-2023, I have the good fortune of sampling three distinct rubber, namely, Rozena ( the softest ), Tenergy 05 ( medium hard ) & Dignics 05 ( hardest of the three ).
  1. Rozena reminds me of Weetabix soaked in milk, its mushy, soft but hey! Some people still love it.
  2. Tenergy05 reminds me of Weetabix on its own, au-naturel. It is crunchy / crispy and just nice to eat on its own. No additional condiments needed. ( NO BOOSTER! Just leave her alone you over-zealous booster loving punks!!! )
  3. Dignics05 is like rye bread. It is dense, hard and you need a strong jaw and teeth to really savour it.
 
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Thank you sir.

Does Friendship 729 Battle Two 38 degrees hardness equally to ESN scales 38 degrees hardness ?

Best regards,
No not at all, and the top sheet of the Chinese rubbers are more often harder than the European, more elastic top sheets as well. So you'll have to calculate with this as well.
 
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Friendship 729 Battle Two 38 degrees rubber equally how hardness degrees of ESN rubber scales ?

Thank you sir.
Best regards,
I have battle 2 provincial 39. I can't really tell how different it is. I think it's about the same with DHS.

What's weird is that some 729 rubbers like battle 2, use a scale similar to DHS, while others like sky wing use a scale like ESN...

I can comment on that, I don't know.
 
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Myth. Just because there is not a simple formula doesn't mean the two variables have no correlation.
So show us the correlation! The formula doesn't have to be simple. Even a graph of elasticity vs hard will do. You can't. I once tried Giant Dragon Guard. It was a Chinese version of an anti rubber. It was hard but if you depressed it you could still see where your finger was for a few seconds. This hard anti was not elastic. I didn't like Giant Dragon Guard.
 
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So show us the correlation! The formula doesn't have to be simple. Even a graph of elasticity vs hard will do. You can't. I once tried Giant Dragon Guard. It was a Chinese version of an anti rubber. It was hard but if you depressed it you could still see where your finger was for a few seconds. This hard anti was not elastic. I didn't like Giant Dragon Guard.
Try me. You can shove that Giant Dragon Guard up your behind. As I've explained, that crap is not elastic, yet you keep using it to justify your distorted definition of elasticity and force it on the vast majority of elastic rubbers.

Here's some real data, data from Sumitomo, same as last time. Same formulae for two types of sponge, with hardness being the only difference.

Test condition:
Sponge ONLY on concrete slab fixed with double-sided tape: 2mm
Hardness scale: Asker C
Ball: TSP 40mm 3-star
Drop height: 2m
Specimen1Specimen2Specimen3Specimen4Specimen5Specimen6
Natural rubber100100100828282
Polybutadiene---181818
...
Primary vulcanization time (min)4610468
Secondary vulcanization time (min)555555
Hardness294857365157
...
Rebound (cm)93.595.496.692.794.094.4
...
 
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