Rubber hardness

When looking for rubbers online each website usually has their own hardness scale from 1-10.
Although Im specifically looking for the hardness in degrees.
Is there anywhere to check this for all rubbers as even on the rubbers official page they do not have these measurements.
bonus Q
Also recently found out that hardness in degrees varies from brand to brand eg. 40deg H3 is harder than 40deg rakza 7. ?
Is there a universal hardness measurement/unit I can use to compare these ?
Just wondering if the Rakza Z is harder than my current H3 provincial 40deg

Rakza Z has ~~50-52 degrees in scale ESN uses
Rakze Z EH has 53-57
Your hurricane 3 has 40 degrees shore A, haggis measured those with shore 0 durometer at about 60

Joola Golden tango has also about 50 degrees ESN, and haggis measured those at 55 degrees.
Xiom Vega China has advertised hardness 55 degrees ESN and haggis measured it at 59 degrees.

Based that I would guess that Rakza Z EH is similar in terms of hardness to that Hurricane 3.

Originally Posted by Vxneji

When looking for rubbers online each website usually has their own hardness scale from 1-10.
Although Im specifically looking for the hardness in degrees.
Is there anywhere to check this for all rubbers as even on the rubbers official page they do not have these measurements.
bonus Q
Also recently found out that hardness in degrees varies from brand to brand eg. 40deg H3 is harder than 40deg rakza 7. ?
Is there a universal hardness measurement/unit I can use to compare these ?
Just wondering if the Rakza Z is harder than my current H3 provincial 40deg

I don't have a durometer but a Rakza Z and a couple of DHS, 729 and ESN rubbers.
The differences in hardness can be felt quite easily in most cases but I can't tell if the Rakza Z is closer to the B2 or closer to the H3 or exactly in the middle. So I would put my Z @ 38.5° or around 50° ESN.
From soft to hard:
Presto Max 46° < Vega Pro 47.5° = Z2 = G-1 = PowerGrip < B2 Provincial 38° < Rakza Z < H3 (commercial and provincial) 39°
With boosted B2 and H3 it's more or less the same: B2 still harder than ESN 47.5° but the Z is closer to the H3 or maybe even a little bit harder.
So I would guess that your H3 40° is harder than the normal Z if unboosted and the Z Extra Hard should be (slightly) harder than a boosted or unboosted H3 40°
The measurements from Haggisv https://tabletennis-reviews.com/refe...ardness-table/ include the topsheet as do my thumb durometer "measurements".

As Igor said, generally 2 scales of hardness, Shore A and O. although there are manufacturers that use their own scale or a different one, Then they sometimes refer to the sponge as, Hard, Mid-hard, Medium, Medium Soft etc

Sponge hardness does not always reflect how a rubber/sponge combo actually feels!!!
A soft sponge with a harder rubber top sheet could 'feel' the same as a rubber sponge combo with hard sponge, soft rubber top sheet!!!

If you want to check sponge hardness, then buy the durometers, use an off-cut from a sheet of rubber and carefully remove enough sponge from the rubber top sheet so you can test the sponge hardness.

Depending on how good the sponge manufacturers quality assurance processes are, will also affect their 'manufacturing tolerance' there can be 'a permissible difference' either side of the stated sponge hardness. in some cases this could be up to 1 or 2 degrees either side.

It seem there is a disagreement? What is measured? The top sheet or the sponge?

Originally Posted by codasa

Rubber hardness is the toughness of the rubber that it is made of.

This implies the top sheet. In industrial uses we measure the hardness of belts to see how long they will last or "toughness" as codasa implies.

Originally Posted by IB66

If you want to check sponge hardness, then buy the durometers, use an off-cut from a sheet of rubber and carefully remove enough sponge from the rubber top sheet so you can test the sponge hardness.

This will result in a much different reading. The durometer tips are so sharp it will penetrate the sponge rubber easily.

Read this about what a durometer is actually reading. It is about how it resists indentation. The durometer tips are pointy not like ping pong balls.
So the durometer reading is good for measuring how "tough" the top sheet is.
https://www.rubbercal.com/industrial...rometer-chart/

Read this about foam rubber. Read the part about closed and open cell foam rubbers and what they say about open cell rubbers.
https://www.rubbercal.com/industrial...sponge-rubber/

codasa is right about the durometer reading hardness or "toughness". Durometers don't measure how "springy" the sponge rubber is.

If I were testing rubbers I wouldn't place durometer readings very high on the list. I would separate the top sheet and stretch it to see how it stretches and how fast it returns back to its original shape. For maximum spin we want the ball to stretch across the surface of the paddle and then snap back quickly.
To test the foam rubber I would cut a 1 cm square and measure the force required to compress it. This provides an idea of the spring constant but it is also import that is snaps back quickly when the force is removed. This can be easily tested by bouncing balls off a sheet.

Durometer readings aren't really that useful for telling how a rubber will play. TT balls are not sharp points.

Originally Posted by brokenball

It seem there is a disagreement? What is measured? The top sheet or the sponge?

This implies the top sheet. In industrial uses we measure the hardness of belts to see how long they will last or "toughness" as codasa implies.


This will result in a much different reading. The durometer tips are so sharp it will penetrate the sponge rubber easily.

Read this about what a durometer is actually reading. It is about how it resists indentation. The durometer tips are pointy not like ping pong balls.
So the durometer reading is good for measuring how "tough" the top sheet is.
https://www.rubbercal.com/industrial...rometer-chart/

Read this about foam rubber. Read the part about closed and open cell foam rubbers and what they say about open cell rubbers.
https://www.rubbercal.com/industrial...sponge-rubber/

codasa is right about the durometer reading hardness or "toughness". Durometers don't measure how "springy" the sponge rubber is.

If I were testing rubbers I wouldn't place durometer readings very high on the list. I would separate the top sheet and stretch it to see how it stretches and how fast it returns back to its original shape. For maximum spin we want the ball to stretch across the surface of the paddle and then snap back quickly.
To test the foam rubber I would cut a 1 cm square and measure the force required to compress it. This provides an idea of the spring constant but it is also import that is snaps back quickly when the force is removed. This can be easily tested by bouncing balls off a sheet.

Durometer readings aren't really that useful for telling how a rubber will play. TT balls are not sharp points.

Hi BB,
Do all durometers have points? Or are there ones that have a larger flat surface area?
Cheers

Originally Posted by brokenball

It seem there is a disagreement? What is measured? The top sheet or the sponge?

This implies the top sheet. In industrial uses we measure the hardness of belts to see how long they will last or "toughness" as codasa implies.


This will result in a much different reading. The durometer tips are so sharp it will penetrate the sponge rubber easily.

Read this about what a durometer is actually reading. It is about how it resists indentation. The durometer tips are pointy not like ping pong balls.
So the durometer reading is good for measuring how "tough" the top sheet is.
https://www.rubbercal.com/industrial...rometer-chart/

Read this about foam rubber. Read the part about closed and open cell foam rubbers and what they say about open cell rubbers.
https://www.rubbercal.com/industrial...sponge-rubber/

codasa is right about the durometer reading hardness or "toughness". Durometers don't measure how "springy" the sponge rubber is.

If I were testing rubbers I wouldn't place durometer readings very high on the list. I would separate the top sheet and stretch it to see how it stretches and how fast it returns back to its original shape. For maximum spin we want the ball to stretch across the surface of the paddle and then snap back quickly.
To test the foam rubber I would cut a 1 cm square and measure the force required to compress it. This provides an idea of the spring constant but it is also import that is snaps back quickly when the force is removed. This can be easily tested by bouncing balls off a sheet.

Durometer readings aren't really that useful for telling how a rubber will play. TT balls are not sharp points.

Agree.

But regarding the sponge I would not cut cut a 1 cm square, as it would not be enough describe the dynamics of the most semi hard-hard-very hard sponges, covered with hard top sheets. Even the softer sponges, covered with hard top sheets, will need greater area to be correctly analyzed.
For softer top sheets, especially over harder sponges, a 1 cm square will be enough.
Though in all cases the result of such measurement will not give to most us /you/ what we /you/ think we /you/ need to evaluate the eventual expectations.

In reality, during the production process, the durometer is used to check the value consistency of the sponge allthrough its area.
Sponge hardness and its consistency is much harder to achieve than the rubber top sheet one.

Originally Posted by IB66

Hi BB,
Do all durometers have points? Or are there ones that have a larger flat surface area?
Cheers

All I have seen have tiny points. Do a search for durometer images. All have small points that don't represent the roundness of a TT ball at all.
Look closely. The small points are very small relative to the rest of the durometer.
https://duckduckgo.com/?q=durometer&...ages&ia=images
duro meter = hard meter or tough meter.
https://www.wordhippo.com/what-is/th...word-duro.html

The duromenter readings really are for measuring the durability of a rubber, not how springy it is.

We used one a work to measure the toughness of belts that were carrying french fries that were being cut by knives. The knives would damage low durometer belts too easily.

Originally Posted by langel

[p]Agree.

But regarding the sponge I would not cut cut a 1 cm square, as it would not be enough describe the dynamics of the most semi hard-hard-very hard sponges, covered with hard top sheets. Even the softer sponges, covered with hard top sheets, will need greater area to be correctly analyzed.

Using a square centimeter is about the same area that a TT ball contacts the rubber. This can be seen from dust marks made by new or dirty balls. Also, it makes it easy to calculate the modulus. It would be easy to put a square centimeter of sponge in a vice in series with a load cell to measure the force as a function of compression. This would basically return a spring constant which is much more useful than a durometer reading.

Though in all cases the result of such measurement will not give to most us /you/ what we /you/ think we /you/ need to evaluate the eventual expectations.

What do you want to measure? Durability might give you an indication if the top sheet will last year or 6 months. I would rather know how springy it is.

In reality, during the production process, the durometer is used to check the value consistency of the sponge allthrough its area.

Not the sponge alone. The sponge isn't very durable. You must mean the top sheet with the sponge below it.

Sponge hardness and its consistency is much harder to achieve than the rubber top sheet one.

Yes! Did you read the thread above about closed and open cell rubber sponge and how it is the air pockets that allow the sponge to spring back? That is what TT players want. It is the air pockets that will compress and spring back. Springy sponge will be light because it will have more air pockets.
Remember, you put air in your tires, not foam rubber.

It makes no difference. What I posted was valid.
It is good to educate the forum on what a durometer really measures.
Basically, I think TT players place too much emphasis on durometer readings. If people like hard rubbers as a preference then fine but I will also repeat that there is too hard and too soft and the optimal lies somewhere in between.
The "made for me, made for you" is pure marketing without fact or justification.
If R53 is good then why not a R60?

The penetration of a round TT ball into rubber is much different than a point sticking into the top sheet.

http://www.guoqiuhui.net/images/2017...0597293479.jpg

http://www.guoqiuhui.net/Home/Goods/.../goods_id/2568

OCS Oxigen Capsule System by STIGA is a sponge material with inner closed cells. This is to keep up a rebounce energy in the rubber for monthes. Hardness by Shore durometer is a statical charateristic of the sponge, it has no direct relation with the amount of speed you get on the sponge. For making realistic evaluations of speed potencia of sponge material you need a resiliometer of Shob type.

Be happy

Fasten your seat belts now and listen to the music. (--- thanks Igor :-))

In Learning, there's no first or last;
When one learns and progresses fast,
Then the last shall become the first --
She would be my Teacher at last. (--- thanks Zeio)

It seems we exchange information by fighting. It made me sad until I realized I actually like it :-)

Originally Posted by zeio

Seeing pnachtwey educate the forum by throwing around terms such as closed- and open-cell rubber, air pockets and "heavier oils...will ruin your rubber by filling the air pockets with nearly uncompressible oil" gives me the chill. It is so uncanny.
Are you lost? You should be posting this in the boosting with baby oil topic.

Thank table tennis god he's finally reached that friggin' point. Would've saved yours truly so many keystrokes if he were that smart 6 years ago. Fuk yeh! It took just 6 friggin' years for our omniscient engineer to acquire, better yet, verify this much knowledge!

The link says it all.
[quote = Zeio]
Anyone who say tension is a scam are noobs "new" to the game.

Where is your formula that uses tension to compute the speed or spin?
What holds the rubber in tension?
I have been waiting these 6 long years.
Tension is a lot different that elasticity.

Originally Posted by zeio

The gas within the bubbles will try to escape into the atmosphere due to entropy, which exerts tension on the rubber.

Entropy? What are you saying? Are you implying the pressures in the closed cells will decrease? It depends.
The gas pressures will seek equilibrium. I would be surprised if they haven't done that while in their plastic packages.
How does the equalizing of pressure increase the tension? If I deflate a soccer ball, the tension on the on the bladder and covering goes down.

So Zeio, where have you been? Why haven't you been telling the noobs that boosting closed cell rubbers is futile?
Maybe we should be asking if the sponge is closed cell or open cell?

I don't boost but I did buy some speed glue that I used on H3 or H3 Neo. I wasn't impressed. I would rather buy a faster rubber.

BTW, why don't you tell us about reduced mass. This forum hasn't heard it.