Isopropyl alcohol to clean chalk?

I carry a small bottle of isopropyl alcohol which I use to refresh my home made liquid chalk.

It also works really well to erase chalk graffiti.

I don't see how it could do any harm to the rock, but am open to counter-arguments.

It's not super good at actually decreasing the amount of chalk, seems to just suspend the chalk particles, then as soon as it evaporates, there they are again.

Which is fine for turning graffiti and prominent tick marks into white smudges, but doesn't make holds any nicer.

I may try using a cloth to absorb the alcohol before it dries- anybody experiment with this?

From my time working in a gym I have found liquid  chalk turns into a pretty dense paste that cakes onto holds and becomes really difficult to clean. If you are adding liquid chalk to chalk it would be the worst scenario I could imagine. 

Good point, Seb.

But I think it's only some commercial liquid chalks that contain resin-like "grip enhancers."

My home made liquid chalk is just chalk and isopropyl, so I can't imagine it has a similar effect.

Mark E Dixonwrote:

Good point, Seb.

But I think it's only some commercial liquid chalks that contain resin-like "grip enhancers."

My home made liquid chalk is just chalk and isopropyl, so I can't imagine it has a similar effect.

It's not the resin, generally I found liquid chalk user to be fine provided they were a little more experienced, new climbers who used it would generally over apply so you ended up with fat globs of liquid chalk worked into the pores of the holds, they would dry and get impossible to clean off.

I would say, try it out on a random little bit of rock see if it works, if so great, if not, no harm done. 

Resurrecting this because I did a forum search on how to clean caked chalk off of rock. There's a mega classic 11a that everyone & their dog gets on. As a result, there's chalk EVERYWHERE. Anyone have any luck on finding a solvent to clean a route covered with chalk?

Distilled water

I was belaying someone who was using a brush to remove chalk from holds., Clouds of chalk were coming off. I was worried that I would get COPD.

Castle Hill in NZ has a pretty thorough culture for removing chalk. Details here: https://castlehillbasin.co.nz/washing

I've played with ideas a while on this but never tested any. I'm guessing a mild-medium aqueous acid, followed by brushing, followed by distilled water, followed by isopropyl would do wonders. I'd be hesitant on sandstone or conglomerate or limestone, that the acid or isopropyl could potentially weakne the matrix material. Someday I'll test it out and report back.

I can’t speak to what works in practice, but the chemistry makes some pretty strong predictions. Chalk is magnesium carbonate. It’s totally insoluble in alcohol which would better be suited to oils and hydrophobic things. Water is only slightly better. A liter of it could dissolve just over a hundred milligrams of chalk if you allowed it to reach equilibrium (which would probably be very slow).

Dilute acids should work much better. Vinegar (acetic acid) should react with chalk in a similar way to what it does with baking soda. It should make CO2 bubbles and magnesium acetate. Magnesium acetate is ~10,000x more soluble than magnesium carbonate, so should be much easier to wash off. You probably wouldn’t want to do this for limestone since that also reacts with acids; no idea about sandstone.

I usually found a thoroughly cleaned  heavily used route looks better for only a short time and then it is caked right back up.

So basically, people should brush their chalk off when they lower off a route

Grant, thanks for the link. Looks like they're using the most natural method, water & brushing. Also sounds like the method that will require the most elbow grease.

Collin, this is the chemistry info that I'm here for. Thanks!

The route in question is in the SE. Our sandstone (from what I understand) is older than the desert sandstone out W. Not as friable but I'll check with some locals/wait for more responses to see if they think that vinegar is OK to use.

Mark, yeah, unfortunately classics bear the burden of getting caked. It got so bad that I couldn't tell which hold to go for anymore. Movement was still good but it made the route so hard to read. Not saying that it detracts from the climb for visitors but it was certainly not as enjoyable to me. I know you've opened & maintained a bunch of routes in rumney, did you just use elbow grease?

Jeremy Lwrote:

Mark, yeah, unfortunately classics bear the burden of getting caked. It got so bad that I couldn't tell which hold to go for anymore. Movement was still good but it made the route so hard to read. Not saying that it detracts from the climb for visitors but it was certainly not as enjoyable to me. I know you've opened & maintained a bunch of routes in rumney, did you just use elbow grease?

So basically it's now as challenging as it would be in the absence of connect-the-dots chalk.

I’m not a chemist, but I know one.

Citric acid (pKa 3-6) is another weak acid that works well. We used it instead of vinegar/acetic acid (pKa 4.75) because it has no smell. Pretty cheap to buy in powdered form as well.

Acids can react with rock though, especially rock that has iron, like certain kinds of sandstone. I would do a test and make sure to use lots of water even if the test went well.

Yes, but now you're holding on to chalk caked holds instead of textured sandstone.

Acetic Acid diluted w/ water. Use caution for limestone, take much more care and have extra water to dilute to non reactive levels quickly....although TBF even VERY weak vinegar/h2o concentration work well at getting chalk out of there and not reacting with limestone IME. It is just something you should be aware of and ready to mitigate if limestone is your substrate.

This topic has been run thorugh before on MP and a search will find more discourse on the topic as desired.

the effects of acid on your gear??

M Spraguewrote:

the effects of acid on your gear??

This is a good read....https://blackdiamondequipment.com/blogs/stories/qc-lab-the-electric-harness-acid-test

M Spraguewrote:

the effects of acid on your gear??

Reduces weight

While acetic acid can theoretically react with iron oxides in rock like hematite-cemented sandstones to produce iron acetate, the reaction would be much, much slower than the reaction with carbonates and would be of lesser concern (occurring over many days or weeks rather than minutes). I nerd out on chemistry, and once wanted to dissolve the magnetite in iron-rich sand in stronger hydrochloric acid (making iron chloride), but decided the reaction was too slow to be worth my while.

To further reduce this possibility, vinegar would be a better choice than citric acid, because the acetic acid in vinegar is volatile (which is partially responsible for its smell), so any excess/residual that wasn’t washed off would rapidly evaporate rather than remaining on the rock.

For rock that isn’t particularly acid-sensitive, it seems like vinegar could actually be lower impact than water if it reduces the need for scrubbing. As for concentration and amount, it would take about 30 mL of vinegar per gram of chalk to fully convert to acetate (vinegar is only 5% acetic acid, and two molecules of acetic acid are required for each molecule of magnesium carbonate). This would need to be adjusted upward if further dilution is used. No idea how much chalk is actually on a chalked-up climb, and it may not be necessary to achieve full conversion if the remaining chalk is loosened up by partial reaction, but if small amounts of diluted vinegar aren’t working well, it might be worth considering this. That could also support trying to first brush/rinse off loose chalk if one wants to reduce the amount of vinegar needed and save it for the layer that is truly stuck (just like the Australian climbers do in the earlier linked video).

The BD link from Mr. Rogers showed that vinegar didn’t rapidly and visibly degrade nylon in the way that hydrochloric acid and sulfuric acid did, but probably still not advisable to get it on soft goods.

Edit: The full results tables weren't showing up properly on my phone, but a 72 hour soak in vinegar caused only a 4% decrease in the strength of nylon, compared to a 91% decrease after half an hour with hydrochloric acid. Only a sample size of one in their tests, but at the very least, it seems unlikely to cause immediate catastrophe.