Polished Rock

Matthew Jaggerswrote:

Lol

I’ll take that as a no   

Its a conspiracy for likes lol

Not Not MP Adminwrote:

You make some valid points, however your understanding of mineralogy and geology is a little off base. For example, just because something is not as hard doesn’t mean it “can’t” wear down rocks. One way of looking at this is thinking about how a pencil eraser can create grooves and smooth things much much “harder” than itself. You could also think of the grooves in rock formed by the repetition of the rope sliding against it from lowering. It also need to be pointed out that Moh’s hardness only applies to minerals and not rocks. Rocks are (typically) composed of many minerals of varying hardness. For example, Wingate sandstone is going to weather, wear and be scratched for more than Nuttall Sandstone due the varying mineral content amongst the two. So trying to use Moh‘s hardness scale to try to quantify a property, like durability, of a rock gets a little murky and isn’t really a fair to comparison especially when referring to rocks as broadly as all sandstone v. all limestone v. all granite. It should also be noted that chalk likely not the main culprit, but a factor nonetheless...albeit a very minute one. Climbing shoe rubber is likely a a larger culprit and would certainly score lower than a 7 on the Moh’s scale…

He’s never climbed on limestone…which may explain why he is so adamant against rock texture actually degrading over time due to climbers

What are you talking about?

All you did was reiterate what I just said. Various rock matrices are made of different composites so just using the Mohs scale isn't great, but when the difference is 3 to 7 or greater, than there is no chance Chalk can wear down granite. Anecdotes aside

Ropes wearing down sandstone is not a controlled experiment and the presence of sand/rock on the rope sheath itself is of unknown quantities. The same can be said of shoe rubber. Embedded crystals, sand, glass from the crag, dog shit, etc are completely uncontrolled.

Sorry but climbing doesnt just stand outside of any empirical science and the one reliable thing we know is that climber chalk, a specific chemical composition, cant wear down rock especially harder types like granite.

J T wrote:

Do you not understand the post regarding Magnesite polishing granite or what? His point is also showing how much you don’t need your precious data in this particular circumstance to understand the point people are trying to demonstrate for you. Let’s ignore chalk, as that seems to be your fixation and speak of other common factors that can polish rock, but are significantly softer than it. Let’s focus use shoe rubber and ropes. By this same logic climbing shoe rubber shouldn’t polish rock and ropes can’t create grooves either since they significantly softer than sandstone and granite too, right? 

Precious data lol

Whats next, deny the moon landing?

There is no data, precious or not, to show an isolated climbing shoe doing damage to rock without outside particulates. Its never been done, so just stuff your conclusions up y---

yeah

Limestone is the worst.  There are routes around Austin where the feet are just like climbing on glass

Yuri Rodeawrote:

What are you talking about?

All you did was reiterate what I just said. Various rock matrices are made of different composites so just using the Mohs scale isn't great, but when the difference is 3 to 7 or greater, than there is no chance Chalk can wear down granite. Anecdotes aside

My point was/is that moh’s hardness has close to nothing to do with weathering. For example, liquid water obviously doesn’t have a rating on the moh’s, but if it were we can safely assume liquid water’s “hardness” would be 0 yet, it polishes granite more and better than any rock does. Again rocks don’t have a moh’s hardness rating so I’m also confused why you’d even try to incorporate it lol There are many other factors that have much more of an actual effect. 

Sorry but climbing doesnt just stand outside of any empirical science and the one reliable thing we know is that climber chalk, a specific chemical composition, cant wear down rock especially harder types like granite.

You got any data to support this claim?   Also you do realize that climbing chalk is the same chemical composition of magnesite which is actually used to polish granite lmao

Grit is the size of the grains used for sanding, not the hardness of the grains. The grit of human skin doesn't matter, the hardness of what is on that skin is the determining factor.

Magnesite is Mohs 3.5-4.5
Magnesium carbonate is often used as a mild abrasive in toothpaste, because tooth enamel is slightly harder at 5 on the Mohs scale.

... course aluminum oxide we get on our ropes and hands is 9 on the Mohs...

While magnesium carbonate is mildly abrasive, I'd think most of the polishing is coming from chalk filling in the low spots, then getting "sealed" with oils from hands.

Edit: to anyone interested... and grit number is approximately the same as the mesh number. When you are specifying an average or predominate particle size in mesh you will typically give a range. IE 80-120 mesh, meaning these particles are small enough to pass an 80 mesh filter, but are too large to pass through a 120 mesh filter. Other times you will only get 1 number, like +20, meaning all particles are retained on a 20 mesh filter, or -200 meaning all particles pass a 200 mesh filter. Or just the number itself meaning the particles are approximately that size, giving you zero clues on the distribution. For sanding wood to a fine surface you may work your way down to finer and finer sand paper. 40, 80, 120, up to maybe 240 to 400 depending on how perfectionist you are. In automotive applications and with wet sanding going up/down to 1000 mesh is often considered a minimum. Polishing acrylic or other clear plastics, like auto headlamps might take you up to 3000. Using paper becomes not that efficient at some point so you buy polishing paste made with very very very fine particles suspended in some goo. Its almost always going to be aluminum oxide, garnet, silicon carbide or ceramic unless you are polishing something real specialized like telescope optics or something.

Desert Rock Sportswrote:

Grit is the size of the grains used for sanding, not the hardness of the grains. The grit of human skin doesn't matter, the hardness of what is on that skin is the determining factor.

Magnesite is Mohs 3.5-4.5
Magnesium carbonate is often used as a mild abrasive in toothpaste, because tooth enamel is slightly harder at 5 on the Mohs scale.

... course aluminum oxide we get on our ropes and hands is 9 on the Mohs...

While magnesium carbonate is mildly abrasive, I'd think most of the polishing is coming from chalk filling in the low spots, then getting "sealed" with oils from hands.

My guess is the polishing-is-fake-news crowd is going reply by saying that tHaT’S nOT pOLisHiNg

Matthew Jaggers wrote:

Jim, how is a super misleading statement about a rock hard stone helping in conversation about a soft, air like powder? Magnesite and climbing chalk are about as similar as bullet granite and deadly quicksand. Just goes to show how people will thumbs up anything they want to be true.

Jaggers, my guy, please do some research of your own prior to making foolish posts like this. Magnesite and climbing chalk are both magnesium carbonate and share the same hardness rating along with many, many other physical and chemical properties. 

You’re so stuck on needing “proof” but won’t accept any evidence people have provided for you lol seriously, climb on well trafficked limestone and get back to us, you may see the “proof” for yourself .…Oh and stop giving your own posts the “thumbs up” if that’s the case. 

In many cases climber's behavior needs to be part of this discussion. For example in Joshua Tree, it's not uncommon to see a group of climbers having a group TR session on a route that's over their heads. Usually this will be a classic 5.10/5.11a line with a more moderate line next door. Many of the more delicate thin routes at Josh have not held up well to being flailed upon. 

Kristian Solemwrote:

In many cases climber's behavior needs to be part of this discussion. For example in Joshua Tree, it's not uncommon to see a group of climbers having a group TR session on a route that's over their heads. Usually this will be a classic 5.10/5.11a line with a more moderate line next door. Many of the more delicate thin routes at Josh have not held up well to being flailed upon. 

I don’t know about this. Are we to the point of discouraging climbers from trying hard on top rope climbs because it’ll polish the rock?

Should we tell Ondra that he shouldn’t have flailed on Silence so much because he was polishing the holds more than his fair share?

Anything softer rubbing on something harder over time will polish it. Pressure and difference in hardness of the two materials will alter the time, and and overall finish. That’s why river rocks are smooth. Water running over them for years and years.

Limestone and granite polish like glass. Limestone much faster. Footholds polish faster than hands. I would guess this is an effect of putting more weight on your feet, and the rubber being more   abrasive than skin and chalk.

Whether or not the chalk protects or polishes is a good question. As someone who has polished things for a living for over 20 years (including metal, wood, plastics, and stones,) I would take an educated guess and say it depends. I would guess that the oils in our skin and sun screen will probably be a better buffing compound, but I would imagine that if you combine chalk with the oils and grease (or water) it will be more abrasive and speed up the process. This is why we tend to see polished holds more rampant in warmer climates, crags that have very humid environments (like beach crags).

I would guess if I took 3 pieces of the same rock, one was rubbed in my sweaty hand, one in a dry chalky hand, and one in a sweaty and  chalky hand the one in the sweaty and chalky hand would probably polish first, the sweaty hand second, and the dry chalk 3rd. This is all speculation.

Also those that think that brushing the chalk off of polished holds will return them to their gritty state obviously haven’t climbed on really polished holds. That would be like putting chalk on a polished granite countertop then brushing it off and hoping it would magically become gritty granite again.

There’s a difference a chalk caked hold and a polished hold.

Water over rocks is more the grit in the water as well as rocks rubbing against rocks and knocking off/down sharp edges (river bed), like polishing rocks in a tumbler w/ water or a ridiculously slow water jet cutter (grit suspended in water). Though some rocks are ever so slightly soluble in it, like limestone, and can erode in that way as well over a really long time.

The shoe rubber is a good surface to carry the grit it picks up from the dirt/sand/rock dust on the ground and your feet carry most of your weight and focus it on the high points, so you have grit rubbing against the highest points of the rock with a lot of weight forcing it down. Your skin will also pick up grit, but it is softer and more pliable than shoe rubber so it can disperse the weight better than just hitting the high points of a hold.

Every one of these threads devolves into this.

Matthew Jaggerswrote:  Never climbed on limestone. 

Oh you'd dig it!!

Humans destroy everything they love. Even each other. There are simply too many climbers/humans. Mother Nature will be taking care of that soon enough... In the meantime; I'll say it again for posterity, " Rock Texturer will become a real job, in the not-too-distant future".

Hank Caylorwrote:

Oh you'd dig it!!

Doubt it. I'm a sweaty dude, and will let the Coloradans have all the limestone for yourselves. I like friction.

saign charlesteinwrote:

Anything softer rubbing on something harder over time will polish it. Pressure and difference in hardness of the two materials will alter the time, and and overall finish. That’s why river rocks are smooth. Water running over them for years and years.

Sorry but thats just not true. The main process of rocks being worn in rivers or other bodies of water is by contact of other rocks carried by the stream. Whether its find grain sand, pebbles, etc. Pure water will not polish rock itself, its simply a carrier medium. Anything softer rubbing on something harder will physically not polish it, by definition. Its simply difficult in real life to have contact between two bodies that doesn't carry some contamination or abrasive particles in whatever scenario you imagine (waxing your car, polishing wood, etc)

This convo is so similar to Micro Fractures back in the day. 

Matthew Jaggerswrote:

Doubt it. I'm a sweaty dude, and will let the Coloradans have all the limestone for yourselves. I like friction.

The red has a nice texture and all but it may be the most humid destination in the country

Matthew Jaggerswrote:

Doubt it. I'm a sweaty dude, and will let the Coloradans have all the limestone for yourselves. I like friction.

Dude. You climb in the Southeast - one of the sweatiest, most humid, generally unpleasant areas in the country. 

You've shown in this thread you really don't know WTF you're talking about.

Marc801 Cwrote:

Dude. You climb in the Southeast - one of the sweatiest, most humid, generally unpleasant areas in the country. 

You've shown in this thread you really don't know WTF you're talking about.

Ahh man now you too will be on his ignore list. You're a bad man Marc.