Blowtorching holds and thermodynamics

Just saw this on the home page and people are claiming that the thermal expansion resultant from torch use will cause rock shattering (e.g. en.wikipedia.org/wiki/Fire-…).

I doubt it (as long as you're not a dildo about it).

I am from the wet Northeast and this was common practice. As long as the holds you're torching have water on the hold surface than rock temps should not be exceeding past 100 c (212 f). Once the hold is dry... you tend to move the torch over to some other wetness.

Anyone care to have a well thought-out scientific debate or shall we just consider this debunked (yes I realize that without looking into the effects of TE at 100 c I haven't really proved anything, but I'm lazy and enjoy debate, hence the post).

Beat ya to this one: mountainproject.com/v/got-b…

;)

Yea, it could mark or damage the rock per the science but anyone who has done it knows it doesn't as long as you are not a "dildo" as you say.
Flame on!

I've studied rock mechanics for 30 years and can't answer the question with any certainty. Seems like there are 4 possible effects; rock thermal expansion differentials (spalling); water to steam; low temperature mineral effects; and possibly chalk/sweat/oils in the pore space. The details of rock type, porosity, permeability, pore size, minerals (especially low tempoerature clays and zeolites) would be really important in all 4 effects. I can imagine anything from no effect at all (imagine a clean, unaltered, unweathered granite) to really messy (imagine heating a sandstone made of weathered volcanic clasts with water bound in clays and low temperature zeolites and an outside layer of chalk/sweat/oil hand scum being heated and permanently driven into the pore space). Interesting question though

Just please stay off the schist with your friggen blowtorch.

I've used a blowtorch to burn out the thick roots left after removing cactus off my routes here in the Potrero Chico.

As a geomorphologist who has studied rock weathering, there is little doubt in my mind that a blowtorch will damage rock. It has been shown that rapid surface heating causes microfractures within the rock. This happens naturally with daily heating cycles, but rate and magnitude are really important. A blowtorch heats faster and hotter than sunlight and can probably cause a lot more damage (at least at the surface). The damage will not likely be visible while you're doing it, but be assured that it will weaken the rock.

M Sprague wrote:Just please stay off the schist with your friggen blowtorch.

U sure? I thinking we should start up a blow torch party at Rumney!!! The torch is actually great at heating up cold holds in the winter so the cold don't hurt ur fingers as much ;-)biting sarcasm... but seriously mark - have you experienced some negative effects first hand up at Rumney.

tradryan wrote:Just saw this on the home page and people are claiming that the thermal expansion resultant from torch use will cause rock shattering (e.g. en.wikipedia.org/wiki/Fire-…). I doubt it (as long as you're not a dildo about it). I am from the wet Northeast and this was common practice. As long as the holds you're torching have water on the hold surface than rock temps should not be exceeding past 100 c (212 f). Once the hold is dry... you tend to move the torch over to some other wetness. Anyone care to have a well thought-out scientific debate or shall we just consider this debunked (yes I realize that without looking into the effects of TE at 100 c I haven't really proved anything, but I'm lazy and enjoy debate, hence the post).

I do not know about rock, but extreme heat can cause concrete to explode. When I was in high school I placed a lit cutting torch on the concrete ground to set my hands free so I could move some steel. After about two minutes the concrete exploded and left a small crater under the torch. I was able to replicate the results again a few later with a thermal lance. But of course a cutting torch and thermal lance are many times hotter than any blowtorch will ever be.

I have personally caused so-called bluestone pavers to fracture (spalling) with a blowtorch. I was really putting the torch to it, but to imply that any non-dildo style blowtorching is harmless is kind of dumb. You may well be capable of torching holds with no problems, but to encourage it among the general public will not end well.

By the way, when it explodes, you'll want to be wearing safety glasses.

So if it's a big enough of a dildo, wear safety glasses?

Around here people build campfires wherever they want. Sometimes idiots build fires right next to a cliff or boulder. I've seen whole sections of sandstone cliff break off due to this.

Do you know what happens to water when it turns to steam? It expands. Somewhere around 1100 times the volume. You can't tell me that water embedded in pores, escaping those pores due to high heat being placed on it will have absolutely no effect on the rock itself. Yeah, once or twice drying it out likely won't do much, but drying it repeatedly sure will.

I have 'thermaled' granite a few times to get rid of saw marks at work. You wet the rock, then hit it with an acetelyne torch. The torch then causes spalling on the surface- as long as the torch is not held in one place too long. No, I don't imagine anyone is using an acetelyne torch to dry holds, but the concept is still the same.

Dan Felix wrote: I don't imagine anyone is using an acetelyne torch to dry holds, but the concept is still the same.

No, it isn't. What you said is like saying that a small hammer and a wrecking ball are "the same concept". And it is destructive to use a wrecking ball to clean cliffs, so we mustn't use a hammer either, right? "The concept is the same."

In the various discussions that have taken place about this topic, on various sites over the past week, a crucial point is continually missed: the blowtorches in question just aren't that powerfull. Yes, rapid, extreme heating will damage rock, but your standard hand-held propane torch just doesn't throw that much heat; about the same as a campstove. You would have to try really hard to damage a rock with such a tool.

Honestly, your nylon bruch and your grubby, oily hands are probably doing more damage to the rock than a torch will.

Could lead to a whole new method for chipping...
Oxy-Acetelyne torches to creatively spall....
Would the result look more or less natural than traditional chipping?

Sorry if I've promoted any thread drift.

CaptainMo wrote: U sure? I thinking we should start up a blow torch party at Rumney!!! The torch is actually great at heating up cold holds in the winter so the cold don't hurt ur fingers as much ;-)biting sarcasm... but seriously mark - have you experienced some negative effects first hand up at Rumney.

Satan on a Halfshell lost a crucial hold back when it was a V8 due to torching.

Luckily the V10 problem it created is one of the best in New England, but it's the thought that counts.

Im loving all the completely ridiculous analogies.

Seriously, you would have to try pretty hard muck up rock with one of those hobby torches. We aren't talking about industrial equipment here, they are little $10 things. A wreaking ball and hammer aren't the same thing, kudos to that analogy for getting it right.

It depends on the rock, red. If it is some big sloper on granite, probably no problem unless it is done over and over again. If it is on flakes or porous rock where water is trapped then you can have a problem more quickly. Like somebody said before, steam is very powerful. It is not like you have to heat the rock up to melting temperature to do damage. Even without steam, thermal expansion can make the surface flake off. Plus, you might fuck up the glue you didn't know was behind that flake ;)

Red Tagger wrote:Im loving all the completely ridiculous analogies. Seriously, you would have to try pretty hard muck up rock with one of those hobby torches. We aren't talking about industrial equipment here, they are little $10 things. A wreaking ball and hammer aren't the same thing, kudos to that analogy for getting it right.

Red Tagger, I find myself agreeing with you completely on an ethical issue. Odd. Perhaps the world actually did end on Dec. 21st.

M Sprague wrote:It depends on the rock, red. If it is some big sloper on granite, probably no problem unless it is done over and over again. If it is on flakes or porous rock where water is trapped then you can have a problem more quickly. Like somebody said before, steam is very powerful. It is not like you have to heat the rock up to melting temperature to do damage. Even without steam, thermal expansion can make the surface flake off. Plus, you might fuck up the glue you didn't know was behind that flake ;)

This is a very reasonable point. The torch is like any one of the many potentially destructive tools in the climber's arsenal, such as the bruch, the drill, etc. All require some thought and care on the part of the user to take into account the vagaries of the rock that that tool is being applied to. All can be damaging if applied carelessly to fragile rock, but all can also be used carefully and appropriately.