The Value of Chalk?

Do you think chalk is an absolutely necessary “tool” for climbers on hot, humid days? If so, you and I are in complete agreement. However, some British researches are convinced that chalk is not as indispensable as hundreds-of-thousands of climbers the world over have believed. The conclusion of their study was that chalk reduced the coefficient of friction (skin against rock surface) and, strangely, water did not! They suggest that “alternative methods for drying the fingers are preferable.” If you don’t believe me, read the study’s Abstract (below).

So, what gives? Did John Gill (the famous boulderer who first introduced chalk to climbing in the mid-1950s) lead us all on a 50-year farcical crusade of chalk use? Are we all delusional in thinking that chalk really enhances our performance on the rock? Do we really have greater friction with wet hands than with chalked hands?

Studies done in a lab are just that–lab studies. They don’t necessary translate to where the fingertips meet the rock in the real world. Chalk up this study (sorry for the pun) as another example of junk science. This is comparable to the recent, well-publicized study that found that Vitamin C damaged the DNA of cells in a test tube. Of course, it’s the effect of Vitamin C on cells in the human body that counts–and hundreds of human studies confirm that it’s an invaluable nutrient.

Clearly, it is true that an excessive amount of chalk will decrease the coefficient of friction with the rock. After all, that’s why you carry that toothbrush to clean off important holds; it is also why it’s a good idea not to over chalk your hands or the holds. However, in the real world–when you are sweating it up on some rad route–we all know that a thin coat of chalk on the finger tips dries the sweat and improves our grip.

My conclusion: Don’t throw away your chalk bag until a “double-blind” study is done with actual climbers moving in the vertical extreme.

Study: Use of ‘chalk’ in rock climbing: sine qua non or myth?
By: Li FX, Margetts S, Fowler I.

Perception Action Laboratory, School of Sport and Exercise Sciences, The University of Birmingham, Edgbaston, UK.

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.

J Sports Sci 2001 Jun;19(6):427-432

Copyright 2007 Eric J. Hörst. All rights reserved.