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Syd


Dec 25, 2012, 2:07 AM
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Chalk ?
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This paper http://www.ncbi.nlm.nih.gov/pubmed/11411778?dopt=Abstract
claims :
"... Finally, water had no significant effect on the coefficient of friction. The counter-intuitive effect of chalk appears to be caused by two independent factors. First, magnesium carbonate dries the skin, decreasing its compliance and hence reducing the coefficient of friction. Secondly, magnesium carbonate creates a slippery granular layer. We conclude that, to improve the coefficient of friction in rock climbing, an effort should be made to remove all particles of chalk; alternative methods for drying the fingers are preferable."

Most of us use chalk to dry the hands and seemingly improve friction. While the paper suggests that moisture does not effect friction, I wonder if it's the greasy components of sweat that effect friction ? I have noticed that washing my hands then drying them thoroughly does seem to improve grip on my hangboard.

Any thoughts or experiences ?


USnavy


Dec 25, 2012, 2:50 AM
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Re: [Syd] Chalk ? [In reply to]
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I dont see where I can actually read the paper. But from what is said in the abstract, I am going to call bullshit on this one. Although it is true chalk reduces friction, it is completely bullshit that water does not. Duck your hands in a bucket of water and then climb some hard route with lots of shitty holds. See how you do. If you want more proof that water acts as a lubricant, the next time it is raining out while you are driving, slam on your brakes and see how long it takes to stop, and compare the results to dry conditions.


(This post was edited by USnavy on Dec 25, 2012, 2:53 AM)


JimTitt


Dec 25, 2012, 7:13 AM
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Re: [Syd] Chalk ? [In reply to]
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"The effect of chalk on the finger-hold friction coefficient in rock climbing"

Authors: Amca, Arif Mithat1; Vigouroux, Laurent2; Aritan, Serdar1; Berton, Eric2

Source: Sports Biomechanics, Volume 11, Number 4, 1 November 2012 , pp. 473-479(7)

Abstract:
The main purpose of this study was to examine the effect of chalk on the friction coefficient between climber's fingers and two different rock types (sandstone and limestone). The secondary purpose was to investigate the effects of humidity and temperature on the friction coefficient and on the influence of chalk. Eleven experienced climbers took part in this study and 42 test sessions were performed. Participants hung from holds which were fixed on a specially designed hang board. The inclination of the hang board was progressively increased until the climber's hand slipped from the holds. The angle of the hang board was simultaneously recorded by using a gyroscopic sensor and the friction coefficient was calculated at the moment of slip. The results showed that there was a significant positive effect of chalk on the coefficient of friction (+18.7% on limestone and +21.6% on sandstone). Moreover sandstone had a higher coefficient of friction than limestone (+15.6% without chalk, +18.4% with chalk). These results confirmed climbers' belief that chalk enhances friction. However, no correlation with humidity/temperature and friction coefficient was noted which suggested that additional parameters should be considered in order to understand the effects of climate on finger friction in rock climbing.

Or
"Instrumented Climbing Holds and the Dynamics of Sport Climbing" by Fuss/Niegl published in Engineering of sport 6 Vol 1

Which comes to essentially the same conclusion with an increase in friction of 32% with loose chalk and a decrease in friction of 8% with wet hands on artificial holds.

Both of which coincide with the experience of millions of climbers worldwide.


Syd


Dec 25, 2012, 1:47 PM
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Re: [JimTitt] Chalk ? [In reply to]
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My own tests on my hangboard confirm what seems obvious. Water decreases grip. A little chalk helps. It would be interesting to see how the authors of the first paper derived their results, if anyone wants to fork out the $36 paywall fee.

There does seem more to grip though. My best on the 45 degrees slopers is a 20 second hang but on other days I can't stick them at all. Too much chalk has a negative effect. Washing hands of sweat and drying thoroughly helps. Humidity seems to have a negative effect.


marc801


Dec 25, 2012, 2:22 PM
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Syd wrote:
This paper http://www.ncbi.nlm.nih.gov/pubmed/11411778?dopt=Abstract
claims :
"... Finally, water had no significant effect on the coefficient of friction. The counter-intuitive effect of chalk appears to be caused by two independent factors. First, magnesium carbonate dries the skin, decreasing its compliance and hence reducing the coefficient of friction. Secondly, magnesium carbonate creates a slippery granular layer. We conclude that, to improve the coefficient of friction in rock climbing, an effort should be made to remove all particles of chalk; alternative methods for drying the fingers are preferable."

Most of us use chalk to dry the hands and seemingly improve friction. While the paper suggests that moisture does not effect friction, I wonder if it's the greasy components of sweat that effect friction ? I have noticed that washing my hands then drying them thoroughly does seem to improve grip on my hangboard.

Any thoughts or experiences ?
That's a 2001 paper and it appears that the 2012 paper cited in Jim Titt's post invalidates those results.

My thoughts are that you've found an older study that ignores thousands of bits of empirical evidence from climbers worldwide over the past 40 years and discussing it further would seem pointless.


Syd


Dec 25, 2012, 7:45 PM
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Re: [marc801] Chalk ? [In reply to]
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I've always used chalk and I've always felt that it improves grip. However here's another paper that claims "powdered chalk actually decreasing the coefficient of friction."
http://pij.sagepub.com/content/early/2012/03/06/1350650112439647.abstract

Any comments from the guys who don't use chalk for environmental reasons ?


bvb


Dec 25, 2012, 11:36 PM
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Really? Chalk?


lena_chita
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Dec 26, 2012, 5:36 AM
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Syd wrote:
I've always used chalk and I've always felt that it improves grip. However here's another paper that claims "powdered chalk actually decreasing the coefficient of friction."
http://pij.sagepub.com/content/early/2012/03/06/1350650112439647.abstract

Any comments from the guys who don't use chalk for environmental reasons ?

I do not use chalk 99% of the time, because I do not feel the need for it.

From my perspective, a hold that doesn't have any chalk on it (say, and intermediate that I use that nobody touches) is much "grippier" than a jug that has been chalked into slippery smoothness by many hands. Also, the holds that have a lot of chalk on them feel slimy when the humidity goes up.

But this is different. There is definitely such thing as too much chalk, and it is reasonable to suppose that having a thick coat of finely ground slippery dust on a hold will decrease friction.

I would bet that the difference between studies that say chalk decreases friction and the studies that say chalk increases friction is in the AMOUNT of chalk used, and the manner in which it was used.

Countless climbers all over the world use countless brushes to scrub that EXTRA chalk off the critical holds -- because, even as they feel that the little bit of chalk on their hands is helping, they also feel that TOO MUCH chalk makes the hold more slippery/harder to use.


marc801


Dec 26, 2012, 9:00 AM
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Syd wrote:
I've always used chalk and I've always felt that it improves grip. However here's another paper that claims "powdered chalk actually decreasing the coefficient of friction."
http://pij.sagepub.com/content/early/2012/03/06/1350650112439647.abstract

I'll try to remember that the next time I'm climbing on polished steel. You might want to reread that abstract...


Syd


Dec 26, 2012, 12:26 PM
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marc801 wrote:

I'll try to remember that the next time I'm climbing on polished steel. You might want to reread that abstract...

You might want to re-read as well, Marc: "the powdered and liquid chalk and agent-free finger were tested on sandstone"


marc801


Dec 26, 2012, 1:10 PM
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Syd wrote:
marc801 wrote:

I'll try to remember that the next time I'm climbing on polished steel. You might want to reread that abstract...

You might want to re-read as well, Marc: "the powdered and liquid chalk and agent-free finger were tested on sandstone"
Correct. It also states:
"The tests on the sandstone showed no real difference between the lubricants or the different conditions, except for the dry, chalk-free finger, which had a decreased coefficient of friction due to the lubricating properties of the sandstone particles."

So in other words, they all work as expected - to increase friction - on real stone.


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