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TradIsGood
Fun-loving climber
the Gunks end of the country
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Topic Author's Original Post - Nov 20, 2006 - 07:45pm PT
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http://www.sportex.bham.ac.uk/staff/lifx_files/Coeff%20friction%20climbing%20JSS%202001.pdf
The authors measured the coefficient of friction of wet hands, clean dry hands, dry hands coated with chalk, etc. They found that dry hands or wet hands were better than hands with chalk.
 This article is cited frequently enough on the web. Does anyone know of any more recent or contradictory research on the topic? Or is there a second set of experiments that confirmed the results of the first?
Research aside, your experience might seem different. If so, consider the following:
My experience (shale or Gunks conglomerate) is that using chalk on your hands on rock with water running on it is way worse than no chalk. You might as well put on a nice gel of toothpaste. Hopefully this is obvious, but if it is not, try it sometime.
So, if really wet chalk is worse than no chalk, and you think at some point chalked hands are better, then there must be a point at which the moisture mixed with the chalk is no different. Any less moisture and chalk is better, more chalk is worse.
Of course, the authors used subjects who were not aware of the thesis - to avoid any bias due to differential behavior on the subjects part.
How would you test the thesis that chalk has an effect on hand-rock friction coefficient?
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WBraun
climber
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Nov 20, 2006 - 08:19pm PT
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Huh?
All I can say is "good grief" ......
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jstan
climber
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Nov 20, 2006 - 08:41pm PT
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Sometime during the last century I took data on frictional force between Gunks rock and both chalked and unchalked hands. I also studied the effect produced by a thick layer of resident chalk residue on the rock.
To do it I suspended the piece of rock as in a pendulum with a spring scale so I could read the Normal Force. Then I had another spring scale to resist motion of the rock as I drew my open hand across the rock. I can't remember whether I fussed around with water. As I remember the article in the ET there were graphs and such. If you know someone with all the copies that is probably the easiest way to get the data, if you are interested. Alternatively, given a mailing address I could go down to Kinkos and xerox the article for you.
Cheers,
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kuan
Sport climber
CA
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Nov 21, 2006 - 12:34am PT
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On a purely aesthetic level, I'd rather see "No Chalk" than really obvious tick marks that map out every move. I try to wipe those away if I use them. In less crowded areas, where the rock is relatively chalk free, I try to swat away ANY chalk marks with a t-shirt before leaving.
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Phil_B
Social climber
Hercules, CA
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Nov 21, 2006 - 01:23am PT
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My favorite chalk story:
We were at Joshua Tree and walking to our next climb. As we went past a blank wall, we saw a couple of guys throwing a tennis ball up onto it. After each throw, they'd dip it in chalk and then toss it again.
After we finished the climb, we walked back. The guys were gone, but there were some other guys looking at the "tick" marks on the wall and going, "Man, how did that guy get up there?"
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Jaybro
Social climber
The West
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Nov 21, 2006 - 02:25am PT
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When you have no toothbrush and need one.
"good grief" Werner=Charlie Brown.
"I will give up my chalkbag whet they pry it from my cold dead fingers."
-some guy, as reprinted in a best of Climing™
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Todd Gordon
Trad climber
Joshua Tree, Cal
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Rock is ugly until it has chalk on it.....
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aldude
climber
Monument Manor
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....and a trail of freshly drilled bolts gleaming in the sun!
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bluering
Trad climber
Santa Clara, Ca.
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...and the smell of 2-stroke gas burning...oh wait, wrong thread. Sorry, carry on.
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G_Gnome
Sport climber
Everywhere, man...
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I remember when that 'study' was first posted. It seemed like a flawed study at the time and it still does. Besides, climbing on sandstone I use chalk as a shield as much as I use it to keep my fingers dry. If anyone doubts chalks effectiveness, let's go bouldering, I guarantee that you will find chalk a requirement before the hour is out.
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jstan
climber
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GG:
Have you a link to the study you mention? Be interested to look at it.
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G_Gnome
Sport climber
Everywhere, man...
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John, I can't find the link to the original study but here is an excerpt and I think we decided that they didn't understand the forces applied while climbing and so the forces they applied in the study were not necessarily relevant.
"According to this, magnesium carbonate REDUCED the coefficient of friction in controlled studies. Abstract:
Magnesium carbonate, or `chalk', is used by rock climbers to dry their hands to increase the coefficient of friction, thereby improving the grip of the holds. To date, no scientific research supports this practice; indeed, some evidence suggests that magnesium carbonate could decrease the coefficient of friction. Fifteen participants were asked to apply a force with the tip of their fingers to hold a flattened rock (normal force), while a tangential force pulled the rock away. The coefficient of friction -- that is, the ratio between the tangential force (pulling the rock) and the normal force (applied by the participants) -- was calculated. Coating (chalk vs no chalk), dampness (water vs no water) and rock (sandstone, granite and slate) were manipulated. The results showed that chalk decreased the coefficient of friction. Sandstone was found to be less slippery than granite and slate. 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.
Use of `chalk' in rock climbing: sine qua non or myth?. F.-X. LI, S. MARGETTS and I. FOWLER.
Journal of Sports Sciences 19.6 (June 2001): p427
If you have electronic reference through your local library, you can access it online via thomson gale reference search.
Here's the intro from the article:
Introduction
Although climbing has been practised since pre-historic times (Frison-Roche and Jouty, 1996), only recently has it become very popular; there are over 4 million climbers in the United States alone (Mermier et al., 1997). The last 30 years has witnessed a boom in rock climbing, which is now a truly international sport. The essence of this sport is to lift the body against gravity to climb on rock faces or artificial structures using only bare feet and hands. To achieve this, climbers rely entirely on an efficient, coordinated contraction of muscles associated with fine balance and, of special interest here, friction of bare feet and hands on the support.
Various aspects of rock climbing have attracted the attention of sport scientists. These include the physiological (Hardy and Martindale, 1982; Billat et al., 1995) and anthropometric (Watts et al., 1997) characteristics of climbers, the energy (Rooks, 1997; Mermier et al., 1997; Booth et al., 1999) and attentional (e.g. Bourdin et al., 1998a) demands of the sport, the biomechanical (Quaine et al., 1997) and motor-control (e.g. Nougier et al., 1993; Bourdin et al., 1998 a,b, 1999) organization of the movements, and sport-specific injuries (Bollen and Gunson, 1990; Wyatt et al., 1996; Jebson and Seyers, 1997; Rooks, 1997). Surprisingly, the grip of the hand on the rock, an essential aspect of the sport and a focal point for climbers, has not received any attention.
Magnesium carbonate, known by climbers as `chalk', is traditionally carried in a bag attached to the climber's waist. Climbers dip their hands in it to cover the fingers and, in an attempt to remove any excess deposit, climbers blow on it. Chalk has been used for years by climbers in the belief that this will dry up sweat and improve grip on the holds. Indeed, chalk has been used unquestioningly in several scientific studies (e.g. Hardy and Martindale, 1982). Applying chalk to the fingers is widely perceived as a sine qua non for a good performance. However, to date, no scientific research supports this belief.
What is the effect on grip of applying magnesium carbonate to the surface of the hands? The elements of response can be found in mechanics, tribology and neuroscience. The problem of grip is a problem of the coefficient of friction ([Mu]). When a tangential force ([F.sub.t]) is exerted on a surface, it will tend to move in the direction of the force applied. To prevent this movement, a friction force normal to the surface ([F.sub.n]) can be applied. The ratio between tangential force and normal force defines the static coefficient of friction: [Mu] = [F.sub.t]/[F.sub.n]. The coefficient is roughly constant for any pair of surfaces. The coefficient of friction can be affected by the introduction of another substance between the two surfaces; this is the way lubrication works. For instance, a layer of oil is often used to reduce the coefficient of friction between two metallic surfaces. Conversely, removing any trace of grease or humidity can increase the coefficient of friction. This has been the basis for the rationale leading to the almost unchallenged use of chalk in climbing: dry skin grips better, chalk dries the skin, so by regular application of chalk one increases the coefficient of friction between the skin on the hands and the climbing surfaces. But is it that straightforward?
For solid surfaces, friction is proportional to the normal force applied and it is independent of the surface area. However, skin -- or the stratum corneum, the outermost layer of skin -- is a compliant material. It is about 10-15 [micro]m thick. It behaves more like an elastomer or thermoplastic than a solid body (Johnson et al., 1993). The properties of this biomaterial depend on many factors, including the percentage of water, pH and temperature. Interestingly, Johnson et al. (1993) showed that the addition of water increases the friction of dry skin. It would appear that the main effect of water is to increase the compliance of the surface asperities and hence the contact area. Frequent application of chalk may decrease the percentage of water in the skin and, therefore, decrease its compliance. Moreover, Wyatt et al. (1996) found that the splitting of the skin pads of the fingertips, a common injury among climbers, is due in part to the use of chalk and its desiccating effect. It appears that, at least from a tribological and medical point of view, the overuse of chalk can have the opposite effect to that intended.
Chalk is used to remove water and sweat. Sweat is produced naturally by more than 2.5 million subcutaneous sudoriferous glands. Sweat is a hypotonic solution with a content of 99% water (Marieb, 1992). Owing to the presence of sweat and the accumulation of various greasy substances collected during the manipulation of objects, the skin can be covered by a thin slippery deposit. Johansson and Westling (1984) have shown that, immediately after washing and drying the skin, the coefficient of friction increases. Therefore, there is an advantage in drying the hands. However, Cadoret and Smith (1996) showed that applying talcum powder to the skin can decrease the coefficient of friction. Magnesium carbonate could have the same effect, so that it may not be the best way to increase the coefficient of friction.
No scientific results directly support the use of chalk in rock climbing. Indeed, some studies (Johnson et al., 1993; Cadoret and Smith, 1996; Wyatt et al., 1996) cast doubt on its usefulness. The aim of this study was to determine the effect of magnesium carbonate on the coefficient of friction and its potential interaction with dampness and type of rock. We hypothesized that chalk would not improve the coefficient of friction for already dry hands and that applying water would decrease the coefficient of friction."
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Ouch!
climber
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If you get diarrhea while climbing, you can lick the chalk off the rocks and ease your discomfort.
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jstan
climber
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Following Ouch! I have to retell the story of my first purchase of chalk. I walked into a cutrate pharmacy in DC and asked the lady if they carried chalk.
She Said, "Yes we do."
I asked, "How much do you have?"
She replied, "Fourteen cakes."
I, of course, said, "I'll take them all."
With a suddenly long face she said softly, "Have you seen a Doctor?"
GG
Whoa! You are one fast typer.
My much smaller study was limited to my hands and as I remember now three kinds of rock. Gunks, Eldorado and some beautiful pink granite John Waterman had packed out from his climbing in Alaska. I swear he must have carried out thirty pounds as a present for his mom in DC.
Anyway I found chalk initially increased the effective coefficient of friction but as soon as the natural texture of the rock begins to be submerged the effective coefficient decreases by as much as 30%. I took to placing the chalk in a used sock whose pair had developed a hole. In order to keep the capital investment down I used a wire tie from a bread wrapper to close the sock. Has held up very well this past forty years and am still using it, but only when forced. Chalk consumption drops by easily an order of magnitude.
You even see marketing pictures of a climber with chalk pock marks all over the rock. Must be the advertising types have never seen natural rock. Incredible difference when there is no chalk.
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G_Gnome
Sport climber
Everywhere, man...
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Ha ha, I am just a really fast searcher, and cut and paster.
I use a LOT of chalk. But then I boulder a couple days a week still. And yes, the rock needs to be kept clean of chalk buildup so that the natural rugosity of the rock can stick to your fingers. I also find that if you coat your tips thickly enough in chalk you can keep bouldering longer before you wear holes in them. Maybe I have some sort of sickness that won't let me quit bouldering until something explodes, and as the rock rarely has that problem it is usually me that does.
I keep Metolius in the black!
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TradIsGood
Happy and Healthy climber
the Gunks end of the country
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Topic Author's Reply - Aug 3, 2007 - 05:53pm PT
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It is definitely worse when other people used it (and left it on the rock).
Definitely worse sitting on the ground, spilled out of somebody's chalk bag.
I am considering golf towel instead. I have only used chalk once this year. (Thin Slabs on a hot day for the run-out thin section. Call me chicken.)
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G_Gnome
Sport climber
Everywhere, man...
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But then I don't find chalk nearly as useful when I am climbing 5.5 like you TradIsBad.
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rockmuelle
Trad climber
B'ton, IN
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I gave up chalk for lent about 6 years ago and haven't looked back. But, when I try to get others to do the same, I'm always met with doubt and suspicion. People doubt that they can climb without it for all the standard reasons: helps them focus, their hands get wet, it looks cool for pics, etc.
Now, I'm not the most hard-core climber out there - I climb mostly gear routes 5.10 and under. But, my home crag for the last four years has been the Red River Gorge. I've climbed in high heat and humidity (and rain) with no problems (well, at least no friction problems) and haven't once dipped in a partner's chalk bag (don't carry my own anymore). When I do jump on harder sport routes, finger friction is never an issue.
So, who else climbs without chalk? Are there scenarios where you still bring it along?
Is there there really a physiological reason for needing chalk or is it all psychological?
Am I just climbing at too low a grade for it to matter ("5.12s" in the gym don't count since, well, they're in the gym, and I get enough second hand chalk from the holds)?
-Chris
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G_Gnome
Sport climber
Everywhere, man...
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I think chalk is far more important on thin face stuff and stuff that doesn't overhang. Once the rock gets steep the holds get big enough that chalk doesn't matter as much. I would still chalk like a fiend, but then I started chalking in gymastics at about 13.
Oh, and if you think chalk actually reduced the coefficient of friction, don't you think that all Olympic gymnasts would be without chalk by now?
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