Increasingly the classic routes on limestone are becoming so polished that the original grades are meaningless. There is of course an argument that the grades should simply be increased but what if the polish could be removed?
Every schoolkid knows that the test for limestone (calcium carbonate) is to add a couple of drops of acid, usually hydrochloric. The rock fizzes impressively, as bubbles of carbon dioxide gas are released.
Could we use acid to scour back the polished surface? Well yes… and no. Simply spraying a route with an acid is not going to work. Unless the acid is in a very strong concentration (and imagine the impact on flora and fauna if that was the case), it needs to remain on the holds for some time. A spray would be too general, not sufficiently targeted, and would eat away at other parts of the rock. As it ran down the cliff, whole areas would be affected by it.
No rest and recovery
Attempts to leave areas of limestone unclimbed to see how long it takes to lose the polish by natural weathering have not been encouraging. Even after several decades the polish persists.
But supposing we could keep the acid in place on the holds for long enough to roughen it up. Based in Bolzano, a stone's throw from the Dolomites, Italian company LeerPa think they have found a solution in the unlikely place of house redecoration. Old buildings, particularly stately homes and palazzos, often have remarkable decorative features hidden away under layer upon layer of ancient paint. The solution is to apply the paint stripper in a thick layer and then add a fabric backing to keep it in place. Left for several hours or even days, this enables the paint to be lifted off in one piece as the fabric is peeled off.
Experimenting with the concept on limestone, LeerPa's scientists claim to have come up with a patented system which stays in place whilst it dissolves the polish and can then be peeled off a day or two later. The fabric used will rot down if not recovered and the stripping compound is biodegradable; a very neat solution to the problem of limestone polish.
They sent us a sample to try out, but unfortunately all the instructions were in Italian!
We sent the sample kit to the BMC Laboratories. Firstly we needed to find some polished limestone to try it out on. Fortunately one of our "researchers" had a memento piece that had come away in his hand whilst climbing on the Avon Gorge. This was generously donated to the cause and we applied a little more polish with some sandpaper.
The paste is mixed and then applied liberally to the hold. A fabric sheet (these come in a variety of sizes) is pushed into the paste.
The really clever thing about the system is that the paste contains microbeads which have far stronger acidic properties. These cause pitting in the surface which greatly increases friction.
We realised after the experiment that the plastic film that seemed to be part of the packaging was actually an integral part of the system. Had we covered our repairs with the film it would not have dried out so quickly and the effects would have been stronger. A problem with the Italian instructions but the system clearly works.
Coming to a crag near you
So this summer expect to see areas of limestone crags fenced off with sick routes bandaged up. We intend to start by restoring some of the classic limestone climbs of the Peak District. Which ones should we choose?
Send your suggestions to firstname.lastname@example.org or comment on our Facebook page.
Thanks to those of you who posted a comment on the article or on the BMC’s Facebook, or emailed us with your suggestions. It seems that quite a few of you would like to see us get to grips with this slippery issue, but unfortunately it’s currently beyond us and we were simply April Fooling.
However, if you do have a serious climbing or walking related issue you wish to discuss and think the BMC can do something about it, then consider taking it to your local BMC area meeting.
What happens at BMC area meetings?
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