UKC

Seems to be an accepted fact that Friction is best when it's Cold, with many climbers preferring to visit such places as Font in the winter months.

I need an explanation.....

Why does the cold create better friction?

Are we talking better friction for our footholds i.e from our boots?

Are we only talking about gaining better friction for smears?

What about edging, any benefit / advantage from the Cold?

Do we also get better friction from handholds in the Cold?

Why do Formula 1 Drivers get better friction from tyres which have been warmed?

From the above I'm guessing cold rubber on our boots isn't that great for friction?

Does this apply to all Rock Types or are we only talking Sandstone and Grit, what about frictionless Slate?

Please educate me....

In reply to Sl@te Head:

well you are less likely to get sweaty hands so that instantly improves that department. I haven't thought about the rest of your questions though...

In reply to Sl@te Head:
0% humidity = non greasy holds, more likely in cold conditions. Only a partial explanation ...I'm sure others will enlighten you!

In reply to Sl@te Head:
i'm so bored i did the search for you.......

http://www.ukclimbing.com/forums/t.php?t=305215

never really seen a good answer to this question.

In reply to Sl@te Head: it is ALL about the hands, i'm always surprised people think it's about the shoes. It's ALL about the hands.

In regards to the formula 1 tyres question, the reason that f1 drivers have to warm their tyres is cos when you're driving that fast normal tyre rubber lasts about a minute, then your tyre blows up, so they have to use rubber compounds that are rock hard and useless when cold, that can withstand the sort of heat you get from belting along at 200mph and extreme acceleration and deceleration. and cos they're rock hard and useless when cold they need to be warmed up before the race can get going.
you can make different rubber compounds that are most effective at different temperatures, climbing shoe ones are quite low temps, cos that's when you get the best friction from SKIN.

In reply to @ndyM@rsh@ll:
what an incredibly informative comment - thankyou - I'm sure I could have come to those conclusions with a few seconds of thought or a google search but that is rather beside the point.

In reply to The Ivanator:

Is that true - I don't know, but would have thought cold air would hold less moisture per volume and therefore have a higher humidity?

Chris

In reply to Sl@te Head: here's a quote from the previous thread referenced above. The comment was made by Andy Turner and struck a chord with me - "if your hands are too cold and dry they'll start to feel glassy. It's about getting that happy medium, which is different for different people."
This is exactly how my fingers felt when I tried to boulder limestone the other day having arrived cold on a motorcycle. It took at least 20 minutes bouldering in too much clothing to get any finger friction which happened once my fingers were producing a little moisture.

In reply to Sl@te Head:

I have always had doubts about friction and cold, and a wander round Fontainebleau yesterday confirmed them... It was cold, not raining but dampness filled the air... the few hopefuls who were attempting to make use of the "improved friction" didn't seem to be having much success

It may be true under certain conditions but in forests cold usually means dampness, not too mention the effect of cold on the human body... warm (but not hot) and dry seem to be the best for friction overall, IMO.

In reply to @ndyM@rsh@ll:

Thanks for the input Andy, I'm not so sure about the above though, surely temp has a big affect on the rubber of our boots. I did a problem recently at Font which was given 3 different grades depending on the Temp / conditions. The climbing was all on the feet so surely this refered to the effect of temp on boots?

Problem 14 at T Rex given anything from Font 5b - 6b 'depending on the conditions of the day and the stickiness of your boots'

On page 212 of the Jingo Wobly guide, this route is given a different grade for Winter, Spring and Summer....

In reply to Chris Craggs:


Maybe what you said there will make sense to me later in the day but right now, it makes none whatsoever. So, for right now.....what on earth did it mean? Specifically "moisture per volume"?

Surely a volume of air can have varying degrees of relative humidity, depending on conditions at the time? In other words, colder air can have a higher RH than warmer air. Or vice versa, it just depends.

In reply to Sl@te Head: Surely this clears it up!!

Abstract. Thermal conductivity, thermal diffusivity and heat capacity per unit volume of consolidated porous rocks have been studied as a function of temperature with air as a saturant, at atmospheric pressure. The transient plane source (TPS) technique is used for the simultaneous measurement of these parameters. An empirical formulation is shown to account for the computation of thermal conductivity of porous rocks in terms of porosity and thermal conductivities of mineral constituents. The measurements showed a linear increase in thermal conductivity with temperature.

In reply to Danny Mac: Thanks for that! Just a bit early in the day for me to get my head round it!

In reply to Sl@te Head: Rubber gets softer as it gets warmer, when it's too warm it'll deform too easily and roll off small features or smears, sort of (but not really, i can't think of a better word to describe what i mean)flow around the things it's meant to stick to, i'm sure there were complaints from climbers from the warmer european sport areas when the anasazi verdes came out because the rubber got too soft in the heat and rolled of small foot holds too easily, hence the return of C4 on the whites.

In reply to Fraser:

I think that was what I was saying - the other guy said cold air = low humidity, which I disagreed with! I was also pointing if you get a volume of air and cool it, the RH will go up - won't it?

Chris

In reply to Chris Craggs:
I'm no scientist ...my original point about cold air apparently leading to less humidity was just based on personal experience. On close summer days I've found limestone (particularly at Swanage and Portland) develops a kind of slight surface oiliness (almost as if the rock were sweating!) that seems to thankfully be absent in cooler conditions, perhaps this is not to do with humidity, but cooler days certainly seem to give more positive friction for hands. This oiliness is definitely not just the sweat from my hands, although that contributes too! Someone of a more scientific bent than myself will probably have an explanation for this phenomenon.

In reply to Sl@te Head: Think about it like when you stick an ice lolly/ lamp post to your tongue. same happens when you hold onto rock.
i would have thought warming you shoes up before hand would be best though

In reply to Sl@te Head: hi ian, yes i would defo agree with fella above! the colder the rubber, the less it deforms, so it will stay on the required hold more efectively, i would presume that boot manufacturers will design there rubber to work best at a nominal average temp? as someone else mentioned earlier it is all about finding a happy medium of many different factors, i.e;

a)actual air temp.

b)humidity, of which i presume is to do with air pressure as well as temp.

c)how porous the rock type is, and how long it will take to dry off, which again is dependent on the above factors!

d)how heavy you are, and how good your footwork is!

skin wise, obviously sweat is the big one, but dont forget it`s your skin that is becoming softer , and just like rubber when its warm, it will start to deform and and roll off the underneath layers. the colder your hands, the less sweat there is, and a lot less loss of skin! and again it also depends on how acurate your technique is!

In reply to Sl@te Head:

Ok, my two penneth: friction DEFINITELY affects footholds, at least on granite. It would be totally inconsistent with my experience bouldering & slab climbing granite to say otherwise.

And humidity is also definitely part of the equation.

I remember one occasion in yosemite in march, two days of heavy rain confined us to card games in the tent - next day, glorious sunshine, vapour pouring out of the trees, off the rocks, etc. That afternoon, the rock was sooo frictional, it was fantastic.

So, the next day, good weather continues. Exactly the same temps, but rocks were DRIER. Could NOT climb the same slab problems, not even close. was not tired at all, and anyway I was mostly doing slab stuff so it was not a power issue at all, and hardly using my hands - the simple thing is, my feet did not stick to the granite as easily, and it was extremely pronounced.

This is the one occasion where I felt I had a very sudden difference in humidity in otherwise consistent conditions, and in this case, increased humidity helped my feet stick.

Also, many of my friends dont use chalk at all, they claim that when their hands get very dry they have less traction (I dont find this personally, but its all individual I guess)

Anyway theres no real conclusions to this endless debate- I think its like reverse swing in cricket- a pretty complex equation.

In reply to chrisdavies: or make the rubber so hot that it starts to melt

In reply to Chris Craggs:

this may well be the case, but generally in the UK warmer weather is far more humid than colder.

In reply to owensum:

i am presuming though that the temp was lower on this occasion, than on the next day when it was dry but warmer? humidity + cooler = good mix for that rock type?

strange one that, never heard anyone state that before,surely thats why chalk came about? allthough i will stand to be corrected!!!

In reply to @ndyM@rsh@ll:
Interesting post, when I was looking at the white 5.10's in V12 last summer, one of the chaps there told me that the Verdes (Stealth ) were made for hot Californian climate and the C4 were for UK temps. Certainly the white ones seem stiffer, I'm sure to be educated soon!

In reply to Chris Craggs: You're dead right Chris. As temperature decreases so does volume, and hence relative humidity will increase. Think about when orographic cloud forms because of air flowing up a mountain side - its just air being forced to rise and cool to a temperature below its dew point, ultimately causing cloud to form.
However, this doesnt mean that humidity is higher in the winter (in fact the reverse is very often true), as the total water content of the air above the uk is by no means fixed; it is this fact that the prevailing air masses in winter tend to be 'dryer' than summer ones that usually leads to the lowered humidity.
And anyway, I always thought 'better friction' in winter was due to non-sweaty hands and the maximum coefficient of friction of climbing shoe rubber being at lowish temperatures - specifically designed as such so that your shoes are most sticky when your hands are most sticky, i.e. least sweaty!

In reply to Toby Dunn:

'Cept when its raining!


Chris

In reply to Toby Dunn:

Is this a typo? Surely it's the opposite? In November the weather is cold and damp... cold air holds less water vapour than hot air so the dampness is more evident. Dampness matters for friction when it is present in the zone between rubber and rock, if water vapour (the invisible gas in the atmosphere, not the visible misty stuff like clouds and fog which is not water vapour but tiny droplets of liquid water suspended in the air) is present on warm days it won't affect friction.

On the other hand when the air is saturated, at present in the woods at Fontainebleau, for example, any cooler surface - rock in the morning which will have kept the cooler night temperature, will tend to condense the vapour and feel and look wet - the friction will be very poor. As the air warms up it will become less saturated (although still containing the same percentage of water) and with the warmer rock there will be less condensation and real dampness, thus better friction.

On some rare days, when there is zone of high pressure and dry cold air comes down from the N E there are occasionally cold crisp days when the rock is dry and it is cold and this may lead to better friction, but such days are rare.

In reply to Bruce Hooker:


Reminds me of a well known mountain guide at Harpur Hill - it had been cold for weeks and the recent arrival of warmer air meant the crag was soaked. His client asked why it was so wet, he scanned the sky with a knowing look and said it must have rained last night!

Chris

Just found this, hope to find some answers.....

http://www.theshortspan.com/features/friction.htm

In reply to Sl@te Head:

Interesting if inconclusive... one quote which amused me:

"We don't climb in the wet so climbing shoes are treadless to maximise grip."

Says a lot about the author! Perhaps he was only thinking of bouldering?

In reply to Bruce Hooker:

>...cold air holds less water vapour than hot air...

This is nonsense though. Air is a mixture of gases; cold air can have just as much water vapour within it than hot air and vice-versa. It doesn't make any difference to think of air as being 'saturated' with water vapour, any more than you could saturate air with nitrogen, for example.

What is true is that when the air cools a larger amount of whatever water is there will condense into raindrops or fog or dew. However, it's a mistake to believe that colder air always means more rain or fog or dew; the amount of water in the air is just as important and that depends on more complex weather like where the air came from and how much ocean water it absorbed etc etc.

So you can have cold, dry days or cold wet days and you can have warm dry days and warm wet days. Which is more likely depends on the details of your prevailing weather systems, but not on the air temp as much....

...which all has very little to do with the topic of friction on rock. So here is a brief summary of my opinion (which is of course definitive).

It is a mistake to think of climbing friction in the way you're encouraged to at school (i.e two flat surfaces moving across each other). We could call this type of friction 'sliding friction', and it has little to do with what happens when climbing. Most of the time we are stood on small edges, and are pulling on small edges. In this case what matters is how easily the skin or rubber deforms under load. Rubber or skin which deforms or tears under load easily will creep off edges and we'll experience bad friction. Equally importantly, rock is not smooth. There are plenty of crystals and pits in the surfaces of most rock and, for the best friction, we would like our rubber or skin to deform a little bit so it can match the shape of the rock, giving much improved holding power.

So there's clearly a balanced to be reached - when hot our skin and boot rubber deform too easily, and roll off edges. When too cold our skin and boot rubber is too firm to meld into the surface of the rock and we'll experience poor friction. People often call these conditions "glassy".
Obviously this is quite a complex balance which will vary between different shoes, skin types, body weights and rock types. So there's no clear answer to whether friction is better if it's cold or not.

Then there's the complicating factor of moisture and sweat. Pure water tends to stick to surfaces (you can see it running down panes of glass which are beyond vertical, for example). This property can allow a thin film of water to act as a "glue" between surfaces, increasing friction.
This is "sticky damp" - a condition beloved of limestone devotees in the UK. Too much water means your boot or skin will mainly be in contact with water, not rock. The friction in this case will be horrible. You might expect sweat to behave similarly, but sweat is not water. It contains oils and fatty acids, which act as lubricants. Consequently, sweat reduces friction dramatically. Therefore, the best friction will occur when it is cool enough not to sweat. Again, this varies from individual to individual.

In reply to Bruce Hooker:
I was definitely only thinking of bouldering, maybe I should of just said that climbing shoes aren't designed for climbing in the wet.

In reply to midgets of the world unite:


I'd better throw away my hair dryer, empty my airing cupboard and then go up the farm and tell the farmer his grain dryer doesn't work then......
And as for all those meteorologists and their fancy theories.....

In reply to midgets of the world unite:



Oh no it isn't!

Remember your O-level geography.... when air rises over the Welsh hills, for example, it cools and is no longer able to hold as much water (in the gaseous state) as it could when warmer, so it rains. The saturation point (ie. the temperature at which air containing a given percentage of water gas becomes saturated - resulting in the point at which some water gas will become water liquid) depends on the percentage of water in the air.

Which, as you say, is not a direct answer to the friction question and temperature, but it explains why in the winter rocks are often damper than in summer. When there is even a small amount of water on the rock this mixes with the dust or vegetable deposits and makes a slimy substance which lubricates the rock. A similar effect happens on rock caked in chalk powder, which turns into slime too in conditions of damp, saturated air.

In the mornings boulders in forests are often slimy till late in the day, so on such days it's best too head for the more open treeless areas of Fontainebleau - the Cul du Chien or the 91, for example.

In reply to Chris Craggs:
When there is cloud cover and the air temp is fairly constant that is true. However the typical good friction day is a still clear day in winter where while a shaded thermometer might be reading 2-4 degrees the air temp in the sun could well be 6-10 degrees higher. In those conditions the very low temps overnight will force the water out of the air as frost which will leave very dry crisp air and dry rock by the time your climbing. Anybody who climbs on a dank autumn or winter day expecting good friction will be disappointed. Hot summers days tend to get more humid as the day goes on as plants pull water from deep in the soil into the atmosphere.

In reply to midgets of the world unite:

Utter rubbish. While water vapour is a gas like any other there is one key difference with say N2 or CO2 in the atmosphere water vapour is in equilibrium with its liquid phase. At STP you can't saturate the air with nitrogen as the vapour pressure of N2 at STP is greater than 1 bar drop the temperature 200 degrees and N2 behaves just the same way as water in the atmosphere. The vapour pressure of water at STP is very temperature dependent and the lower the temp the lower the vapour preasure of water. As air cools then the partial pressure of water vapour gets closer to the vapour pressure of water (i.e. the humidity rises) when the vapor pressure is equal to the PP of water then the air is "saturated" i.e it can hold no more water vapour and water won't evaporate. If the temp falls still further and the PP of water becomes higher than the vapour pressure of water then liquid water will form on any nucleation site and you will get dew and/or mist forming. Because water is bellow its boiling point at STP you can't just keep adding more water vapour to the atmosphere.

In reply to chrisdavies:


I know I couldnt quite beleive it when I saw it, but three different people adopt this - I assume it has something to do with a person natural levels of oils that they produce in their hands and their propensity to sweat. Two of these people have bouldered V10 and above, and never use chalk (in fact go to lengths to remove it from problems) so I do trust that their decision is the right one!! well, for them anyways. They dont do it for ethical reasons, they really dont care if rocks are unsightly because of chalk marks - they use it to make tick marks.

But yes, weird, and inexpicable.

In reply to Sl@te Head:

Hmm what about air pressure? I mean, if it is a low pressure day then it should be easier to float upwards....

In reply to Dave Flanagan:
Just read your article, very interesting and informative.....

Have you climbed on Slate? If so what are your top 'Friction' Tips for climbing on 'Frictionless' Slate?

In reply to davidwright:

Yes, but cold air can hold as much water vapour as you like and just as much water vapour as hot air. Of course water vapour condenses as the partial pressure of the water vapour increases but this is nothing to do with some mythical water-vapour bearing property of air. When *the water vapour* cools, it condenses into it's solid or liquid phase because thats how the water vapour behaves. It would behave the same way if the rest of the atmosphere vanished overnight. The only way the temperature of the air comes into anything is because the water vapour is often, but not always, in rough thermal equilibrium with the rest ofthr atmosphere.

So, as I said; to describe cold air as being able to hold less water vapour is just nonsense.

In reply to midgets of the world unite:

You didn't do geography, or science, did you? Several of us have tried to explain, but it seems to no avail

In reply to Bruce Hooker:

I think he may have done Bruce. A grounding in the physical sciences is probably one of many requirements for a RCUK Fellow of Astrophysics at the Universtiy of Sheffield

In reply to Bruce Hooker:

Well, I did study GCSE physics and geography, and A-level physics and a degree in physics, and a PhD in physics so I guess I didn't do any Science, no. I quite understand what you and others are saying, but you're not understanding my point. Perhaps you're so sure of what you were taught that you haven't stopped and thought about what I wrote. I'll try again. It's the temperature of the WATER VAPOUR that determines the rate at which water vapour condenses from the atmosphere (along with other factors like the partial pressure of the water vapour, which governs the rate of collisions with nucleation sites, and the size and shape of nucleation sites). The temperature of the air has very little to do with it, unless you mistakenly assume (as you have) that the water vapour has to have the same temperature as other components of the atmosphere.

The way you have framed the problem (cold air can hold less water vapour than hot air) is factually incorrect, and leads you to erroneous conclusions when dealing with mixtures of gases not in thermal equilibrium. Example: a volcano emits a cloud of water vapour, which rises rapidly through two layers of air. The first is cold and dry, the second hot and laden with moisture. At what point do clouds form? You'd have us believe it's in the cold layer of air, because it couldn't "hold" all that water vapour. In fact, it's more likely to be somewhere in the hot air, because the water vapour has cooled more by then, and the hIgher humidity means more sites for the water vapor to condense on.

In reply to Bruce Hooker:

Or, looked at another way: let's say I accept your assertion that rain over the mountains occurs because the air cools as it rises, and can thus hold less water vapour.

Believing that this is why it rains, I would reach the erroneous conclusion that in an atmosphere consisting only of water, there would be no rain!

In reply to midgets of the world unite:

We are talking about air containing water vapour, as it contains other gases - oxygen, nitrogen, CO2 etc. In this case all the components will be at the same temperature.... The example of a large quantity of one component (water vapour in your example) being injected into the surrounding atmosphere is quite different. I'm sure you see this really.. at least I hope so.

In reply to @ndyM@rsh@ll:

I'd be interested to know whether you have ever felt a F1 tyre. At room temperature it is much much softer than climbing shoe rubber & at racing temperature is virtually like soft glue (which is why (when qualifying for example) they are usually only good for a lap or two)..

In reply to midgets of the world unite:

A given volume of cold "air" can contain a lower quantity of water vapour than the same volume of warm "air". If you put in more water vapour while holding the temperature constant then that the water will condense (unless we are talking about an uncontained block of particle free gas where the mechanics of condensation won't work). The same is true of nitrogen, CO2 and O2 just that the meanings of "cold" and "warm" are very different. Ok this is determined by the thermodynamics of water rather than any properties of the diluant gasses, if any, but then that will be true of any system where the gas aproximations hold. Yes you can have a canister of 100% water vapour at 293 but you can't have it at ~1 bar so the idea is not a useful one when discribing the behaviour of air.

I am not sure you can really have a mixture of gasses that aren't in thermal equilibrium. By the time they are mixed enough to talk about a mixture rather than 2 layers and a boundary zone you will also have a thermal equilibrium.

In a system where the temperature and pressure are held aproximately constant (an assumption that holds in meterology, where a pressure change of 5% is large and temp doesn't change by much more than 10%) then % content becomes a good suragate for pp. (Personally I would also use the chemists equating of conc with pp and % content with purity). More importantly the % saturation of water vapour is a measurable quantity where as the PP of water vapour requires additional calculations to determine. All of which makes a description in terms of saturation and carrying capacity more valuable than one in terms of the PP of water vapour.

If the concept of water saturated air was nonsense then there wouldn't be so much effort put in to measuring the % saturation of water in the air or to predicting how that value will change over time and space.

In reply to davidwright:

Much of what you say is true. It's quite easy to get a mixture of gases that aren't in thermal equilibrium, but let's not dwell on that.

The thing is, you yourself admit "Ok this is determined by the thermodynamics of water rather than any properties of the diluant gasses", so agree that it's false to think of air as having a holding power for water. So what's wrong with describing that assertion as "nonsense", which is what I've done. Your post above merely points out that because the temperature of the air is usually close to that of the water, the concept gives roughly the right answer in some situations.

So I post another example below* to show that in other situations to idea that air has a holding power for water gives the wrong answer. Since we both agree it's not factually correct, at what point do we agree it's "nonsense" that should be replaced by a fuller description of the physics like the one you've provided, and move on?

*Example:

I have a cold mass of air sat above a freshwater lake and the same, cold, air above the ocean. The sea and the ocean are at the same temperature. Using the erroneous concept that air has an ability to "hold" water vapour, which is dependent on the temperature of the air, explain why the saturation point of the air above the ocean is lower than the saturation point of the air above the lake? Can't? That's because the saturation level of the air doesn't depend upon the air. It depends on the water.

In reply to midgets of the world unite: Can we stick to the subject please ....FRICTION,FRICTION, FRICTION.

My brains hurting reading all this!

In reply to midgets of the world unite:

Have you never heard the saying: "When you're stuck in the bottom of a hole, stop digging!"?

In reply to owensum:



It's good to know I'm not alone. Perhaps we should start a support group

In reply to Sl@te Head:


... actually it sounds like there *is* plenty of friction going on in this thread.... !

In reply to Bruce Hooker:

Why? do you need someone to explain it to you?

In reply to Bruce Hooker:


Oh good lord. I'm impressed that you've now managed to post responses that are smug and sarcastic whilst simultaneously offering no substantive defence of your position. Perhaps it's because your original statement is so wrong-headed you're struggling to come up with one?

Since you obviously won't, or can't, take time to understand the actual physics, and why it differs in important ways from the "air-holds-water" myth, perhaps you'll accept it from wiser (and more qualified) heads than mine?

In his book "Clouds in a Glass of Beer", Craig Bohren (Distinguished Professor Emeritus of Meteorology) described your initial statement as "the windbag hypothesis", "a thought-cliche" and "defiling the grave of Dalton". Alistair Fraser (Professor of Meteorology) describes it as "an emetic explanation", and points out a range of weather phenomenon that cannot be explained by the air-holds-water myth, including "the transformation of a water cloud into an ice cloud, the formation of haze, the metamorphism of a snow pack, the formation of steam fog...". Steven Babin (Senior Meteorologist) has written a short history of what he describes as a "commonly held myth", and points out that the mistake was resolved in a paper published in 1802!

I don't know, perhaps this link is apposite

http://xkcd.com/386/

In reply to midgets of the world unite:

this may help.
http://www.atmos.umd.edu/~stevenb/vapor/index.html

In reply to midgets of the world unite:

So what you are saying is that rain doesn't fall because masses of air rising over hills cool down and the water vapour condenses?

Coming back to the reason for this partial hijack, the question was if friction is better in winter and I pointed out that this was not always true as it was often damper in winter (talking of Fonatinebleau but the same applies in many places)and that in the mornings the rocks were damp due to the condensation on the cold rocks making a slimy surface. You can confuse things as much as you wish but it doesn't make this less true... If you cool down air containing a lot of water vapour it's going to condense as it gets colder.

In reply to Bruce Hooker:

You can confuse things as much as you wish but it doesn't make this less true... If you cool down air containing a lot of water vapour it's going to condense as it gets colder.

No Bruce, you are confused.
If you cool water vapour you get cold water vapour.
If you cool it further you get snow.
If water vapour strikes a cold (enough) object the water vapour falls below the `dew´point and water condenses on the cold surface.

Is this not simple?

In reply to Bruce Hooker:

i nearly spat my tea out when i read this,
i dont know stu but i knew about his astrophysics back ground

In reply to Sl@te Head:
It has to be a dry day in winter and after the sun has got on the rocks, and it works for sandstone and grit but I suspect not other rock types. Sandstone oozes moisture given a chance, less when its cold. Its about damp creeping out of the rock onto the holds. Obviously only the bits without green slime etc.

In reply to hedgepig:

Thanks for getting this Thread back on track!

So when it comes to climbing on my preferred rock - 'Frictionless' Slate, can we conclude either way whether there is an advantage in terms of Friction when it's Cold?

Will my rock boots perform any better or worse when it's cold on those tiny slate edges?

Do I need to concern myself with Friction issues when edging?

A project I'm working on at the moment on some steep slate has some very precarious moves using smears on some very smooth / glassy holds where friction can dictate success or failure. As far as gaining maximum friction on these holds what 'Friction' tips do you have? (excluding using POF!!!!)

In reply to Sl@te Head:

Clean shoes thoroughly, no chalk on the footholds. They're the only variables over which you have any control.

In reply to i.munro:

The variables I was looking at were temperature related, i.e is it worth climbing in the cold for better friction or not?

In reply to jimtitt:


What makes you think that water vapour goes directly from gas to solid states? Try a somple experiment, stand up, open your curtain, breathe on the window pane... What do you see on the glass, ice? nothing visible (water vapour is an invisible gas)? Or.. condensed, liquid water? Which is the relevance to this thread as it explains why friction in winter can be poor as this it what happens to rocks when the weather is humid, but not necessarily raining.... which is what I posted a while ago, before the pseudo science high-jack.

Where do you think rain comes from?

In reply to mark s:

And what does astrophysics have to do with this sort of question? Not much apparently. I have a degree in chemical engineering, a subject a bit more closely related, but I don't put it on my profile nor do I think this means I am necessarily right... Scientists can get things wrong too, as can engineers, there are enough examples around. If you really want to know about the subject try google or wikipedia, although most people should remember from school.

In reply to Bruce Hooker:

I think Midgets studies water vapour in the atmospheres of planets in other star systems, amongst other things.

In reply to Bruce Hooker:

Bruce my dear chap; I only brought it up because you asked directly (and in patronising manner) about my science experience. Whilst I never claimed my astrophysics background makes me necessarily right, the names I mentioned above should show I am at least well-read on it. I can't recommend the "clouds in a glass of beer" book enough by the way.

To the original poster; I am genuinely sorry for hijacking the thread! As Vik and Bob might say, I just couldn't let it lie. The answer to your question is that it's definitely worth taking advantage of cold conditions on slate. The biggest difference is that you won't sweat as much, and the natural oils in sweat are the friction-killer.

In reply to midgets of the world unite:

Less concerned about the friction on handholds, more concerned about some very poor footholds on my project.

In reply to Sl@te Head:

Genuine smears will be better at moderate temperatures, but cold weather will be better for edging, because the rubber will roll less. If you need that 'brand new' stickiness from your shoes the soles will benefit from a thorough clean to remove as much fine dirt as possible; I've resorted to putting my shoes in the washing machine with no detergent and on it's coolest setting before, and they do come out as sticky as the day they were bought...

In reply to midgets of the world unite:

What do you define as 'moderate' temperatures?

And the science behind 'cold weather being better for edging?

I'm guessing that the smaller the edge the more reliant it is on friction?

In reply to Sl@te Head:
Rubber friction is odd, in that if you plot friction versus temperature for a given sliding speed it will have a pronounced peak. So for a given type of rubber, there ought to be quite a sharply defined temperature at which the friction is best. This optimum temperature, in principle, will depend on the roughness of the surface it's sliding on, so you'd expect for a rubber whose peak friction for gritstone was around zero that on a smooth rock like slate this peak would be shifted up in temperature. Some years ago there was a very long thread on UKC in which I tried to explain this in the face of some scepticism ...

In reply to Sl@te Head:

The relationship between edging and friction is not that straightforward.

When you're stood on a pure smear, rock boot sole flat against a flat surface of rock, it is "sliding friction" that's keeping you on. As said just above, the amount of friction depends on the nature of the surfaces and on the temperature.

Edging is slightly different; if you visualise standing on a perfectly horizontal edge with a perfectly horizontal rockshoe, there's no sliding friction involved in the physics here at all. In this situation the critical factor is whether the sole of the rockshoe deforms under pressure.

In general for good edging performance you want a harder rubber (it wants to be cold). For sliding friction you want softer, warmer rubber (up to a point).

The complication is that real climbing fits neither of these ideals. Edges are not perfectly horizontal, and neither is your foot, so friction comes into play even on edges. What this means is that if you're looking for an answer like "you'll get best performance at 5degrees", then there's just too much going on for that to ever be realistic.

Finally, when it comes to footwork, technique is a much bigger factor for most than shoe performance, which is why folk like Nic Sellars can climb slabs that most others can't, even though he's sponsored by Boreal, manufacturers of the world's slippiest rockshoe...

In reply to midgets of the world unite:


No, you started saying it was nonsense before this, my reply to was your post. I just had a look at wikipedia to try and see what you were trying to say and noticed the reference about how water would condense at a given temperature and pressure if it was the only gas present - I suppose this is what you mean, but it is a rather absurd consideration in a real world where we are talking about the real atmosphere, not one without oxygen etc., which would lead to other difficulties... The way people say that air "holds" water may upset your pedantry, but most people realise that there aren't little hands holding the stuff... The water vapour present in air is just one of the component gases, it is part of the air we breathe, with the difference, already pointed out to you by another poster, that at normal temperatures it can be present in both gaseous and liquid states unlike the other components of air. You have started with what is essentially a quibble on words,and then kept on digging out of stubbornness.

The fact remains that in normal circumstances all the components of air will be at the same temperature so there is a limit to what proportion of air can be water vapour for a given temperature and pressure: if the temperature drops below a certain level then the excess water will condense to form droplets in the form of mist, clouds, or rain or condensing on things like windows or, what interests us here, rocks. In cold weather this will allow air to contain less water gas than in hot weather (this is where you are quite wrong, you say : " but cold air can hold as much water vapour as you like and just as much water vapour as hot air.").

But the truth of the pudding is that in the winter the rocks in the forest often stay damp and very slimy all day, the condensation over night just never dries off, especially in the areas with mosses and moulds or chalk deposits.

The other factor which hasn't been mentioned is the physical state of the climber, especially the fingers which below a certain temperature lose strength... all in all climbing in the cold is no easier for most people than climbing in dry, moderate temperatures. The only way to really push your ability in terms of foot holds is to buy some new shoes... for a week or two you'll find yourself doing stuff you hadn't been able to do normally, but this could be seen as cheating a bit like the use of pof.

Off to bed now, I'm an hour later here.

In reply to Bruce Hooker:

Replies like that make me feel that you don't actually read what anyone else writes with very much care. My response was clearly in reply to you asking what astrophysics had to do with anything. I was just saying it was you who said I'd clearly never studied science, and I was responding to that when I mentioned my science background.

You said cold air holds less water vapour than warm air. This is wrong. In physics, when a proposed model is not correct, and fails to accurately predict the real world it is wrong, and it is not "pedantry" to say so.

Since I'm clearly not doing a very good job explaining why the dIfference between what you think and what I know is important, I'm going to stop trying to explain. If you're still interested, the clouds in beer book is very good. If you're only half interested I think there's a page called Bad Meteorology, which has a discussion in full, as does the link posted by Simon above.

In reply to midgets of the world unite:


In the previous post I pointed out that this is a metaphor that is often used... all you are doing is showing why "scientists" often have difficulty communicating their "knowledge". In your case the latter seems seriously poor even, are you still maintaining that when you said "but cold air can hold as much water vapour as you like and just as much water vapour as hot air." you were saying something that is true? (second time of asking).

In reply to Bruce Hooker:


`When water vapor in the atmosphere condenses directly into ice, bypassing the liquid phase, the resulting forms are properly called snow crystals.´

Encyclopedia Brittanica

In reply to Bruce Hooker:
In an attempt to bring this Thread back on track (again)and to avoid any more 'Friction'........Here's another question.

(By the way I got a Grade F in A'Level Physics even though my Father was a Physics Lecturer!)

Friction requires 2 different surfaces which has been discussed on here i.e Boots / Rock

Temperature can cause things to Expand and Contract, my question is does this have any effect on the surface texture / smoothness / roughness of the rock (and therefore any difference to the friction we may gain / loose from this?)

In reply to Sl@te Head:

From my own experience i've found the best friction days to be cloudy, odd showers, with a good wind. I've found it more important to have clouds and wind for optimum conditions over temperature.

In reply to Bruce Hooker:

I so want to walk away from this thread but then you rile me again by casting aspersions as to my knowledge when you are quite quite wrong. By the way, I'm not saying it isn't an often used metaphor. I'm saying it's wrong.

I do still maintain that cold air can hold just as much water vapour as hot air. Water vapour exists in an equilibrium with the liquid phase of water. Not an equilibrium with the air. So, it is the temperature of the liquid water, that determines how much water vapour can exist, not the temperature of the air. Dalton understood this in 1802 when he wrote that gases in a mixture "exist independently of each other".

Now, in the very specific case you're banging on about, the liquid phase of water just happens to be water droplets in the air, which will be at roughly the same temperature as the air. So your 'often used metaphor' gives the right answer, but that doesn't mean it's right. There are many scenarios in the real world where the liquid water phase and the air are at different temperatures (cold air above a warm ocean, for example). In these situations your often used metaphor gives the wrong answer. Because it's wrong. It's a wrong metaphor. Or nonsense, as I wrote three thousand posts ago.

In reply to Sl@te Head:


the answer to that is no. The expansion of rock/rubber with temperature is very minor. With rubber the resistance to deformation depends strongly on temperature. This is the dominant effect.

In reply to Sl@te Head: I always thought that particularly on grit that the rock got covered in dust in hot dry spells and friction improved after it had rained and dried off again. In winter there is less dust and more rain so the rock is essentially cleaner.

In reply to Sl@te Head:

Both edging and smearing performance are improved as you reduce temps (up until a critical point where 'friction' drop sharply as the rubber becomes too hard). That critical point will depend on the brand of rubber on your shoes but is likely to be well below zero.
UKC should be publishing an article on Rock shoes shortly. It should give a useful explanation of the science of 'stickiness' and edging, albeit in basic terms.

In reply to Richard J: Sliding friction isn't really a useful measure of 'stickiness' for climbing rubbers - once it starts sliding you are usually off. It is static friction that is important.

Iain