In reply to Chris Craggs:
> (In reply to LeeWood)
> [...]
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> If you think about it logically, the original roughness has been worn away to leave a polished hold. If you remove the polish with acid you aren't bringing back the original roughness. The new layer would polish double quick - deffo a law of diminishing returns at work here.
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Not necessarily. It depends on the rock. I might agree for limestones & other fine-grained rocks but I'm not so sure about courser grained stuff like sandstones and granite. In fact I'm not even that sure about limestone. Part of the polish is surely just that - polish, a build up of chalk/rubber/grease filling in the pores and gaps between grains and evern putting a layer over the rock. Like resin in Font. If you remove this polish with a cleaner that doesn't dissolve any part of the rock you may get back to something resembling the original.
We tried this as an experiment in a dank quarry that was used for a training and the holds had become horrendously slippery. A judicious wash with patio cleaner and the place was back to the day after it was quarried. However it soon returned to it's former state.
And that, I think, is the real issue, unless something changes with the use of the rock then your wasting your energy cleaning it, and quite possibly damaging the it for no reason. It'll just return back to it's polished state.