UKH

Any informed views on the best way to clean overchalked rock would be appreciated. My current approach is patience and a soft brush, which has some but limited effect while protecting the rock.

Uninformed, but I've often wondered if ones of those pump action pressure washers might be useful.

Bog roll soaked in tomato ketchup, lay it on the holds for a few days, the gel like nature of the sauce and the paper hold the weak acid on the hold, rather than it running away. Also removes polish from limestone.

Or brown sauce if that is your preference.

Brush and water.

Thanks for the suggestion (if not a wind up) but I can't imagine doing that.

Not a wind up, a Spanish pal has been using it. The weak acid in the sauce does the job fine. In the UK, we have the weather advantage so probably don't need the bog roll and don't need to wait more than a couple of days for the weather to clean the residue off.

It would make sense that it would work - the vinegar would react with the magnesium carbonate chalk to form magnesium ethanoate which will be readily soluble in the water in the sauce. 

I can't imagine the reaction you'd get if someone spotted you covering all the holds on a climb with a generous application of Heinz or HP Sauce. 

Some the people I know, actually use or have used it. Seems to work at least on hard rock like granite. 
 

Perhaps not the best for porous rock, like grit or sandstone though… as for it to dry might take long and it might not be evident that it is wet (e.g. washed during a dry spell).

also I think it might not be strong enough to clear the Most caked and persistant holds. Some mechanical work might be needed (soft brush). Also taking care of the run-off. If not done properly, you’ll have white water streaks everywhere.

so Yeah, works but not for every case and might require some more thought than required.

I can see a few problems with this. On overhanging/sheltered rock I can see the residue last longer than expected. If anyone wants to do the climb in the 'few days' expected to clear it, they will not be happy.

Nitric acid and steel wire brush. If we can't look after our nice things, we shouldn't have nice things. Dissolve those holds back to ground level!

Also good on chipped holds. 

Oh yes, well done sir.

Of course, and in those cases it would need a rinse.

The middle classes will of course squeeze an artisan organic lemon on the holds.

I was at my favourite local spot yesterday amd was dismayed to see chalk everywhere, including tick marks. Literally every handhold had a tick mark on some of the problems... including the starting holds and jugs! I spent quite a while brushing, but was quite upset that no doubt these idiots will continue trashing the place. If I spot them, I'll do well if I manage to have a calm word with them, as it's a precious place to me.

Best way to clean off chalk?

Don't use it in the first place

Only works, if you're the only one climbing there...

Unfortunately that is not the situation for the majority of posters here.

So yeah, if everyone would do that now... problem solved... just like the grade of TPS

If you're not feeling like Don Quijote, then some constructive advice and common courtesy go a long way. Simply put, leave the place/problem in better condition that when you got there. Clean your own chalk (marks) and rubbish... as well as clean also those left by others. Job done...

Or instead get annoyed, don't actually do anything and post on UKC to show your announce .

Water and a brush? no?

Fire! and lots of it.

Maybe but I need to be careful about unintended negative outcomes e.g. perhaps streaks of white residue that look worse than the original mess.

I've done quite a bit of chalk cleaning over the years.  You can't get rid of it completely as far as I can tell; there's always going to be some residue, for sure with water and a brush but also with vinegar and other weak acids.  Perhaps the answer would be dilute muriatic acid, one part acid to six parts water.  That's one of the things used to clean graffiti.  I haven't tried that so don't know, but paint removal isn't the same as chalk removal...

Since chalk use is not going away, the best thing would be to encourage climbers to use chalk socks, which cuts down on the deposited amounts enormously.  But the likelihood of ever getting wide enough adoption to make a real difference seems to me to be nil.

I'm loath to recommend using acid on rocks with a carbonate content... while it might remove the polish on low grade limestone it might do a bit more to a carbonate cemented sandstone.

Is citric acid, as an example, more reactive with Magnesium carbonate (chalk) or calcium carbonate (cement in some sandstones)?

Thanks for the input.

To reassure any reading this thread: I have no intention of applying any form of acid, ketchup etc to rock anywhere (but appreciate the input from those who posted in the thread with such suggestions). Or even water. I will stick to soft brush and patience.