Tuesday, April 26, 2016

Science Friction Addiction

The science of friction for our climbing addiction.

Have you ever tried to sort dry papers with a dry finger and had to lick your finger to make it stick?Have you spit on the palms of your hands and rubbed them together until they feel sticky to get a better grip on the dry handle of an axe or baseball bat? If you have then you know how moisture/wetness, that we think would decrease friction and make things more slippery, can actually help increase the friction coefficient in many cases.

When taking a closer look at the friction skin on the palm area of our hands and bottoms of your feet as well as the surfaces of most objects under a microscope you can see that what may appear fairly flat and smooth is actually rough with many tiny peaks and valleys. The peaks between the valleys are called "asperites" and are what come in contact when the two surfaces touch. The more surface area you have equals the more friction you will have. So, you want more rounded or flatter asperites with less sharp peaks and less deep valleys so you get more surface area coming in contact and therefore more friction. In the case of climbing you want more friction between your hands and the rock or whatever surface you are trying to cling to. Moisture softens the skin and makes it more squishy and therefore it will have less jagged asperites with more surface area in contact and in turn, more friction.

I touched on the concept of moisture helping certain extremely hard to grasp "sloper" handholds about the year 2000 when I was woking on and finally got one of my hardest boulder problems, a local Bay Area sloper test-piece done first by world famous rock climbing star Chris Sharma named "Eco Terrorist" V10. It was V11/12 when first done and was not repeated quickly due to a dynamic at the time futuristic start move followed to an extremely sloper and for most people, condition dependent, and awkward lip crux. Strong local Jeremy Meigs finally got the first repeat of it in the classic old video West Coast Pimp. Then I was one of about the first 10 locals to repeat it. A few strong friends that had struggled on it asked how can I hang onto the notoriously heinous slopers with my notoriously sweaty ass hands. I thought about it the next time I was there and repeated it and also thought about it several other times over the years on hot humid days at castle rock and all along the coast on slick sloper rocks. The chalk sometimes would make a kind of paste like glue combined with my sweat or moisture on the rock sometimes and it was very complex to figure out exactly when too much or too little chalk was needed.

Charlie "Chuck" Barrett crushing the sloper crux of
"Eco Terrorist" V10 barefoot!
Castle Rock CA.

I started using rubbing alcohol to dry my hands prior to chalking up for hard climbs or boulder problems on warm/hot days when I would sweat a lot. It works well in extreme cases but pouring alcohol on your hands a few times a day several times a week is not the best thing and it would also dry my hands out on trips to arid desert rocks and I would often suffer long lasting deep splits and cracks in the skin of my hands from the skin being to dry. I also used to stay away from moisturizers. Once the cracks and splits became more of a problem than having soft hands for climbing I began to try moisturizers and didn't notice any major change at first. I think that if you climb with soft skin and go through a hard to handle break in type period where it wears out over and over, if consistent in the skin torture, in the long run this could give you very thick but still most almost normal skin on the palms of your hands.

Eventually "Liquid Chalk" came out on the market and I thought it might be the big solution to my sweaty hand friction problems, but not, after about a tube and a half of testing I realized it just made more of paste like mess for my sweaty hands and especially worse maybe in the humid place I lived. I could see how it could be great for me on trips to arid desert rock areas and for people who live there but I have since gotten into mostly just either rubbing alcohol (70-90% is best imo) when it is hot and just mainly, varied levels of chalking.

I have run the gambit on trying things to help climbing for my overly sweaty hands and after 27+ years of abuse and healing my hand skin feels and looks pretty normal, albeit a bit sweaty, and it works fine for most climbing I do except when it is hot and humid and at indoor gyms usually. If I travel to dry arid rocks with sharp holds I may need a short warm up period for my skin of maybe a day or two of climbing then a day or two or three of mostly rest to heal up the flesh wounds and my thick soft skin is usually dried up a bit and toughened enough to be ready for action on razor crimps. The soft skin works much better for me than having it overly dry all the time and trading everyday sensitivity and soft hand friction benefits on slopers simply for the rugged toughness of leather calluses for razor crimps or pockets especially for me since there are less of those types of holds on my local rocks - more jugs, slopers and features and less pockets and crimps.

Often it is hard to tell if it is better to dry the rock and hands with a towel and then chalk up or or some mix thereof might be better depending on three key points; texture of the rock, humidity of the air and temperature of the air which produces hand sweat from body heat and also heats the rock directly heating the hands as well for a double whammy.

The second time I heard about the sticky wet friction was more recently from a very strong local climber/boulderer/routesetter/first ascentionist Giovanni "G" Traversi and it inspired me to look into the science of friction for climbing even more. I found a few good articles touching on chalk use and wet hand friction. Mostly the study of friction for climbing is from places like the Europe/UK where it is very wet for most of the year so they get used to climbing in moist conditions. The Gritstone does happen to have the highest friction value of any rock in the world when dry so that is interesting to note. Giovanni mentioned that when he first tried and new problem that he and his older brother, the world famous Carlo Traversi put up it was a bit moist from a light rain/mist but he tried it anyways since it was steep and the crux was not too wet. G said he was actually able to hold the crux sloper better when it felt moist. Then he said he was there another drier day and tried to repeat it with his brother and they would spit on their fingers and then lightly chalk to get a purchase on the slick polished sloper crux hold of the old abandoned project of mine now a new test-piece called "The Hand of Perseus" V12 FA: Carlo Traversi.

Giovanni "G" Traversi eyeing the sloper crux hold of 
"The Hand of Perseus" V12
Secret West Sonoma County Schist

From what I have read online in the limited articles that only touch on certain aspects of these highly complex and cutting edge ideas and methods to achieve the best friction for your skin each different day on each different rock with different changing weather - rain/mist temperature/humidity is a tough thing to figure out exactly but knowing a few tricks can help you get past those extreme sloper cruxes a bit easier or though a day of less than perfect conditions. The inventor/innovator/pioneer of tough climbing moves in North America and the first climber to regularly use gymnastic chalk for climbing and bouldering, also the creator of the original American B-scale for rating difficulty of boulder problems John Gill was the first to achieve about ~V9/10 in the 1950's using chalk and his gymnastic training and his math professor brain to usher in a new era of climbing challenges. In about 2006 there was a post on the infamous SuperTopo forum titled "when is chalk worse than no chalk" or something like that and it had a few interesting posts from John Gill. Climbing guides at the Grand Tetons in the 1950's would practice climbing on the boulders near Jenny Lake where Gill was setting more difficult boulder problem challenges and remembers seeing them use pine sap and dirt before he began using his gymnastic magnesium carbonate chalk to get a grip on some of the sweaty sloper handholds. He also mentioned that spit from a cherry Lifesaver can help friction in some extreme cases :)

Simply knowing that soft hands can be good in some cases may also let you moisturize those crusty old dry calloused and cracked and split leather climbing mitts you've thought were the best for friction but are mainly only good because the skin is tough and rugged. There are so many variables though, such as, if the rock you are climbing is sharp and your hands do not have enough thick callused skin on them then they will at some point get at least minor abrasions if not even deep cuts. If your skin is too dry and callused and you are trying to hang onto a dry sloper hand hold crux on a very slick smooth rock on a cold dry day then chalk will likely decrease friction unless you are sweating out of your hands a lot then chalking up a little and wiping the excess off with a towel will probably be best or maybe even using a moist towel or spit and rub together could help achieve the needed friction.

Recently I found myself over-chalking before starting a long boulder problem I had just fell off of on my flash attempt with moist hands. It had a dynamic jump move to a huge sloper for the start. The jump move and swinging and milking rubbed all the chalk of my sweaty hands on my first go. On my second go I slapped more chalk on my palms than I usually ever would on a normal problem in order to have some still left on my hands for the crux at the end after wrestling through the start. The crux came right after the starting jump and it was too hard to stop and chalk anywhere so I dealt with the excess chalk and it paid off by having enough left on my palms to feel drier and less sweaty at the crux. So chalking up especially for harder levels of difficulty can be very complex when climbing on many different rock types, in different weather conditions and for different people skin types and levels of sweat or no sweat.

There are many basic variables to friction for climbing from what I have read so far;

And of course this is only hand friction, shoe rubber friction is a whole other ball game! I also learned a bit more about rubber friction when researching this article and the main point to remember for shoe rubber friction is that most modern climbing shoe rubbers are made to be their stickiest in cooler temps to be able to work at their peak performance level where the optimal kind of goldilocks zone happens with the balance of cool temperature (~ 30-50 degrees F) for the hands meets the prime stickiest friction levels of the rubber. So climbing when it is cool is not only good for the hands to be drier and more like leather and therefore more tough and resilient to abrasion but also less sweaty and maybe needing more chalk, which both sweat and chalk can decrease friction overall.

Chalk dries a sweaty or moist hand but it does not create its own better friction in most cases. Too much chalk and not enough moisture can make a thick layer of callused skin that is good for sharp crimper edges, sharp pockets and rugged crack jamming but that hard dry skin will also be more prone to splitting and cracking so it is up to what type of climbing you are doing and and on what rock type and how sweaty or dry you and the environment are.

Slick rock, sloper hand hold may be better to have a slight amount of moisture either before chalking or in extreme cases maybe even instead of chalking like when you spit on your hands and rub them together to grab a dry handle.

Moist hands are less abrasion resistant and on sharp rock can be cut more easily than dry calloused or chalked hands in most all cases.

Sweat and spit and other liquids can be a bit oily or filled with things like sugar or salt etc that do not help friction so pure water is usually the best to use to create stickiness for gripping most dry smooth surfaces.

People that do not sweat as much out of their hands and/or do not push the extreme levels of difficulty (~ 5.12/13+ or V6/7+) and climb at arid dry rocks often will not need as much chalk and in some cases maybe no chalk at all.

Chalking too much can hinder you in certain instances such as very rough gritty rock like 50 grit sandpaper where the chalk will fill in the rough texture and make a smooth surface without the tooth like bite. This and filling in edges and pockets with chalks are the most common reason for brushing the holds between tries or at least after a lot of chalk buildup. The friction skin on the palms of our hands (and the bottoms of our feet) also have the same thing happening but at a much less noticeable level with the ridges of the fingerprints getting filled flat and smoothed over with chalk. So with too much chalk on dry hands it is like the chalk becomes ball bearings between your skin and the surface you're trying to cling to decreasing friction in almost all cases.

Sloper testing at Vertex Climbing Center.
Left hand no chalk / right hand chalk.
Not a major difference this day on this hangboard.
~Inconclusive. More tests to come.

Overall Summary:
Get up and go climb with or without chalk or even worrying too much about conditions! For all you know that V12 you are working on only dry cold days with only the best pure magic pixie chalk on your hands may be better in warmer moister conditions and with less chalk. Maybe. Or maybe you need to chalk the hell out of your sweaty paws and slap most of it off in a big cloud of dust depending on the problem and the day and the person. My friends and I will keep trying these moist hand sloper techniques and theories out in the field and report back any updated findings.

~ May 1 2016

Climbing friction science articles & forum posts:

Climbing.com - Friction Science

Physics - Atomic Friction

SuperTopo - When is chalk worse than no chalk?

UKClimbing.com - Mysteries of Friction

UKClimbing.com - Best when it's cold?



Also found in: ThesaurusIdiomsEncyclopediaWikipedia.

tack·y 1

adj.  tack·i·ertack·i·est
Slightly adhesive or gummy to the touch; sticky.

Some more random unedited ideas about friction - edits and updates coming soon.!?:

the peaks and valleys get filled in with liquid which creates more surface area coming in contact and the surface friction / tension(??) helps create more friction. 
*i sweat a lot when i exercise and so my hands sweat a lot when i climb. i live near the pacific ocean in northern california where it is a redwood rainforest that can be a bit humid and often foggy and misty staying wet for many months. my sweaty hands combined with the moist rocks create an unusual challenge for me and others that sweat like me or live where it is humid. climbing on sloper handholds, mostly on short difficult routes or boulder problems requires holding either very small crimpy edges or very slippery sloping lumps and features. after 27+ years of gripping or slipping i came up with pretty good ideas for getting my hands to grip the rock. i found that for certain very hard boulder problems and some short hard routes (hard for me anyway - V7-V10 or 5.12-5.13) with bad sloper handholds in a few rare and extreme cases it can be better to try different levels of moisture to get a better grip, ((??add to article;; such as when you spit on your dry hands and rub them together to get a grip on an dry axe or baseball bat handle or lick a dry finger to get purchase when sorting dry paper) and/or at least not think that it will hinder you as much as it would seem to climb on some moist holds or with sweaty hands. once in awhile the sweat on your hands or the moisture on the grips can actually help to get a better purchase on some slippery slopers with correct conditions.
the in the slab-vertical-slightly overhanging angle since steeper routes usually have endurance routes with bigger sized hand holds or with a short hard crux near the ground i would use the rubbing alcohol prep+wet towel+then different levels of chalking depending on the heat and humidity and sweat levels and the type of hand holds. for crimps if it is hot i am just screwed but the rubbing alcohol prep and then chalking up combo help. for slopers it is the rubbing alcohol and dry + then moist towel and rub together until they feel sticky then chalk if needed and then stick like glue and crush it! :)
for most tough crimpers, cracks and certain slopers people with sweaty hands in hot humid/wet conditions may want to consider using rubbing alcohol to prep the skin by using it to close the pores for a few minutes and stop sweating depending on temperature and how much you perspire out of your hands. you can add a bit of water on damp towel to create the exact tackiness you desire and then either no chalk or the precise amount of that as well, anywhere from a finger tip dip to the full blown crushing of chunks between the palms and clapping a dust cloud into the air~! 
people with dry hands in cold arid/dry conditions may not want to use rubbing alcohol prep since they are already dry it could lead to cracking and splitting of the skin.
of course most skin is soft and like soft rubber it may be very sticky on frictions smears with maximum surface areas and for the hands on big slopers on certain textured surfaces but on sharp edges or for overall long term abrasion resistance the softer it is usually the quicker it wears out or is actually cut or pierced. 

FrictionLabs - Frictile Dysfunction :)

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