Colophony & Climbing Surfaces

Since COVID, a lot more liquid chalk is in use at climbing gyms and astute gym owners have observed something: the holds seem to have become harder to clean. While liquid chalk effectively solves the dust problem in gyms, it seems to introduce a new one for routesetters: more time spent cleaning holds.

The main ingredients in liquid chalk are alcohol, magnesium carbonate, and sometimes colophony (rosin/pof). There’s an interesting difference between magnesium carbonate and colophony: colophony dissolves in alcohol, magnesium carbonate does not.

This means that the magnesium carbonate in liquid chalk is actually in suspension, i.e., it separates from the alcohol over time. In a transparent bottle, you can easily see layers form when left on the shelf for a while. You shake the bottle to bring the MgCO3 back in suspension.

Colophony on the other hand DOES dissolve in alcohol, and that’s the basis for our little experiment. We want to figure out what happens to climbing surfaces when liquid chalk with and without colophony is used.

Our hypothesis is that a thin film of rosin is deposited on the holds that is harder to wash off with water than regular magnesium carbonate.

Let’s proceed with some basic kitchen chemistry to test our hypothesis! Science FTW! We take two tubes of commercially available liquid chalk, one with colophony (white label product from China) and one without (Magic Chalk by Chalk Rebels).

The first thing we want to do is to dry out the liquid chalk, which is fairly easy to do: cut open the bottles, pour the contents in a bowl, set it outside, and let the alcohol evaporate. It’s useful to run this experiment on a hot sunny day, heat speeds up the process.

After a couple of hours, we end up with two bowls of magnesium carbonate residue. Notice that one of them is considerably more white than the other one. The more yellow-ish bowl is the one that contains the colophony.

When you dip your fingers in to this, you’ll notice that it pretty much acts like regular powder magnesium carbonate. You could just throw this in your chalk bag and go climbing.

But we won’t! The next thing we’ll do is take 5 spoons our of each bowl, put them in a small sealable container, add pure alcohol (96%), close the lid, and let is sit for a couple of hours.

But wait, didn’t we remove the alcohol from the liquid chalk at the beginning? Why add it again now? Two reasons: first, different manufacturers use different grades of alcohol and we want the alcohol content in our experiment to be equal for both kinds of liquid chalk. Second, we want to use the highest possible alcohol content (96%) to help with extraction.

After a couple of hours, we observe that all magnesium carbonate has sunk to the bottom. In theory, the alcohol layer on top of the magnesium carbonate should contain the colophonium since it easily dissolves in alcohol while MgCO3 does not.

We now use a pipette to suck up the alcohol and put it in a small dish. Something like a large Petri dish or glass plate would have been best, but all we had in the kitchen were glass IKEA bowls.

We now set the bowls out in the sunshine again and let the alcohol evaporate. After evaporation we expect to get a thin film of rosin with traces of magnesium carbonate.

And indeed, what we find after a couple of hours of evaporation is that there is a thin layer of sticky dried residue at the bottom of one bowl and no sticky substance in the other. Tada! We have isolated the rosin!

This confirms part 1 of our hypothesis: some liquid chalks will leave a thin film of rosin on climbing surfaces.

Now let’s proceed with the next part of our experiment: how do we clean this stuff? I need those bowls back or my wife will kill me! The second part of our hypothesis was that this thin layer of rosin is hard to wash off with water.

And indeed the bowl that did not contain the rosin was easy to clean with just warm water and a regular kitchen sponge. The rosin one was impossible to clean with just water. I had to whip out a wire sponge and some alcohol to clean it completely.

While cleaning our experimental setup with alcohol works, this is not a viable solution to clean plastic holds or the rock. 

Conclusion: avoid liquid chalk which contains rosin / colophony for both outdoor and indoor climbing. You'll make both the rock and gym owners smile. May I suggest "Magic Chalk" by yours truly? ;-)