posted by: guest date: 2002-08-22 time: 10:34:38 reply x
As it's now summer (so we're told) and the grit is feeling a bit greasy, I got to wondering why. Obviously, I know full well that the handholds get sweaty, that's simple. But why the footholds? Is it just me getting some psychosomatic friction loss because I'm told it should be greasy, or does anyone else agree that footholds too are less sticky in the hot? It's this that I was confused about- surely friction should be better when it's hot, like on a racing car or bikes tyres, which get slippy in the cold and at the start of a race? Maybe I just need more to think about during the day.... If you ask me it's minging climbing in the hot anyway. And the cold.
postId: 355 posted by: dave date: 2002-08-22 time: 10:45:55 reply x
In reply to post 353: To be honest i wouldn't say it makes any difference to footholds. If footholds do get sweaty then there are only a couple of suggestion i could make: 1. I heard somewhere that certain rocktypes can hold moisture in the surface layer, expelling it when it gets hot. 2. maybe your foot-sweat is somehow getting out through your boot??? no that bollocks surely.
postId: 356 posted by: guest date: 2002-08-22 time: 10:49:45 reply x
In reply to post 355: Imagine that! I think I'd be worried if I sweat that much- delirious with water loss from the feet! maybe I was just imagining it- it seems to be mainly on the harder, polishy types of holds. Not a boulder, but like the iron oxidy ones on via media for example.
postId: 357 posted by: dave date: 2002-08-22 time: 11:33:43 reply x
In reply to post 356: Maybe its cos when its hot your boot rubber gets softer. Although technically you would expect more friction, maybe cos its softer you get a greater sensation of your boot slipping, thus it feels like you've got less friction?
postId: 358 posted by: mike date: 2002-08-22 time: 11:48:20 reply x
In reply to post 355: I think you're right about the surface layer sweating thing, and it does apply to grit and sandstone. Also noticed it on the Grochan in the pass - the rock goes all "soapy". If that's the case, then rubber wouldn't stick as well as on a cold day, just as a tyre has less grip on a damp road. But I think the real issue is with your hands. Problems that are easy in winter can become way harder on a hot day.
postId: 360 posted by: dave date: 2002-08-22 time: 11:59:43 reply x
In reply to post 358: just thought of another thing - i think warm rubber sticks better to a cool surface. I would guess that on a hot day the the crag, both rockshoe and rock are of a similar temperature, whereas on a cold day rockshoe is a bit warmer than the cold rock (even if the rubber is a bit cooler than in summer), thus better friction.
postId: 363 posted by: guest date: 2002-08-22 time: 14:00:29 reply x
In reply to post 360: i had a week of frost at the font in february this year - cool, dry and sunny. then on the last day it clouded over and the temp increased from around 4-5 degrees to about 15 degrees. anyway, the boulders started to sweat, releasing all the moisture that had been frozen inside - most boulders literally had beads and beads of water on the surface (kinda like it had just rained except, for once, it hadn't). amazing to see, but shit for climbing!
postId: 381 posted by: mike date: 2002-08-23 time: 20:08:24 reply x
In reply to post 363: That's just plain weird - weeping boulders!
postId: 383 posted by: guest date: 2002-08-24 time: 09:10:20 reply x
In reply to post 363: I think a more likely explanation is moisture in the air condensing on cold boulders.
postId: 392 posted by: dave date: 2002-08-28 time: 10:36:24 reply x
In reply to post 383: surely if it was condensation then it wouldn't appear upon an increase in temperature??
postId: 394 posted by: The Devil date: 2002-08-28 time: 12:30:56 reply x
In reply to post 392: He's right you know!
postId: 397 posted by: guest date: 2002-08-28 time: 16:25:13 reply x
In reply to post 394: it was sweat - no doubt about it. weird!
postId: 401 posted by: guest date: 2002-08-28 time: 18:24:41 reply x
In reply to post 394: The temperature of the ground changes more slowly than the temperature of the air - i.e. it takes time for them to cool down or warm up. So if the air temperature suddenly increases 10 degrees, the air will be warmer than the boulders, hence the condensation.
postId: 402 posted by: dave date: 2002-08-29 time: 07:36:59 reply x
In reply to post 401: That probably true aswell - who knows it is probably due to a combination of factors. I can still belive that the rock does hold some moisture though cos that kind of sandstone can deffinetley absorb water - thats why is get softer when wet.
postId: 412 posted by: mike date: 2002-08-30 time: 05:41:49 reply x
In reply to post 402:
This question does get asked a lot - it`d be good to know the definitive
answer - it`s true sandstone does hold water which makes it snappy, and in
some foreign areas, climbing is `banned` in wet weather.
postId: 415 posted by: jim date: 2002-08-30 time: 07:49:02 reply x
In reply to post 412:
Moreover, I think it`s evryone`s responsibility to back off on wet
sandstone. I recall my first trips to Northumberland, being told not to
climb when it`s wet. Not so much a ban, but I for one wouldn`t fancy
facing the wrath of the county boys if `their` problems started getting
unneccesarily worn
