OOAK Table Tennis Forum

I was wondering.. how does the density of the wood affect playing characteristics? Is density always correlated to weight?

P.

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Current setup: Babolat Pure Drive GT 135th Anniversary Edition + Luxilion Big Banger Alu Power 16/19 26k

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I think there are a number of threads which relate to this topic. For example, these two: The properties of different types of wood and Make your own blade.

In short, the general rule is that greater density usually corresponds with greater hardness and stiffness (although there is no strict formula for this). For instance, Ipe has a specific gravity of .91 (i.e very dense), a Janka rating of 3680 (i.e. very hard) and a co-efficient of elasticity of 21,840 MPa (very stiff), compared with Western Red Cedar SG .30 (light), Janka 350 (very soft), and CoE 7,660 MPa (not stiff).

Your second question: yes, density always correlates with heaviness.

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"So long, and thanks for all the fish
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Thanks Tassie! That would imply density isn't a characteristic that is separate from hardness and elasticity, so it doesn't really tell us something extra about playing characteristics.
P.

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Current setup: Babolat Pure Drive GT 135th Anniversary Edition + Luxilion Big Banger Alu Power 16/19 26k

OOAK Interview with Joo Saehyuk

Well, yes and no. The tricky bit is What density does tell us is how much weight a particular timber will contribute to the blade. It is "separate from hardness and elasticity" to the degree that different timbers may weigh the same but be different in other respects. So, if you look at Ross Leidy's website - Ross Leidy's Handcrafted Blades - you will see that Mottled Anigre and Southern Cypress have similar density ( SG .40 cf .42) but their hardness is significantly different: Janka 930 cf 600. The slightly lighter wood is actually noticeably harder! At the same time the Anigre is about the same hardness as Koto (Janka 930 cf 940) but significantly lighter: SG .40 cf .65.

Ross gives both SG and Janka for his veneers because you need to know both. I think coefficient of elasticity is also useful because it's the measure of stiffness which can vary between timbers of similar hardness.

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"So long, and thanks for all the fish
So sad that it should come to this" Sung by the dolphins in The hitchhiker's guide to the galaxy

Thanks again, Tassie. Very useful information. As I understand it correctly, density surely determines the weight of the ply, so a different density could make a difference between two wood layers that have the same hardness & elasticity, althought mostly woods with same hardness & elasticity have also the same density.

But again, what are the effects of density then? Let's take Anigre and Koto. Hardness is the same, but Koto is more dense. In what way playing characteristics of Koto are different from Anigre?

Pipsy

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Current setup: Babolat Pure Drive GT 135th Anniversary Edition + Luxilion Big Banger Alu Power 16/19 26k

OOAK Interview with Joo Saehyuk

You might find it interesting to read this: Wood! a blog by Ian Worz - he gives some useful and interesting comments on the playing characteristics of different timbers, which you can use to draw your own conclusions about the effects of density. My guess (and it is nothing more than a guess) is that denser - and therefore heavier - timber would be faster than a timber of similar hardness given the extra weight, although my gut reaction is that it will be very small and probably very difficult to gauge. After all, we're really only talking a few grams here; it's not like the difference between a brick and feather!

I still maintain that modulus of elasticity is a big factor. JRSDallas's extraordinary contribution to Denis' Table Tennis World points to the (complex) correlation between vibration and speed. It seems to me that a light timber (low density) with high stiffness (modulus of elasticity) is going to be faster than a heavier timber with low elasticity. Again there is a rough correlation between stiffness and hardness, but because all these qualities vary from timber to timber - and piece from piece within species! - it all adds up to a very complex puzzle.

In the end, lists like Ian Worz's and our very own list - The properties of different types of wood give us good ideas about what we can expect from a particular timber.

_________________
"So long, and thanks for all the fish
So sad that it should come to this" Sung by the dolphins in The hitchhiker's guide to the galaxy