[i_a_coops]

I want to do a route and it's a bit green. I've worn out a 50p soft bristle toothbrush and it's still really scrittly where I don't want it to be scrittly.....

Brush recommendations and general grit cleaning advice welcome 🙂

[SA Chris]

Some crags and probs at this time of the year you might be fighting a losing battle. You cannot degreen something that wants to be green until spring.

[cheque]

Something like this (wooden bristles) is the best sort of grit cleaning brush IMO.

What’ll really make the difference is  a good blast of sun and/ or wind so the lichen’s not holding any moisture though. The recent cloudy evenings and southwesterlies (I think it was from the east today though) won’t have helped northwest-facing crags in that respect.

[Johnny Brown]

Clean when it's really wet, when the lichen is soft and come off easily. Climb when its really dry. This will require two visits.

[Fiend]

Clean when it's really wet, when the lichen is soft and come off easily, but don't scrub too hard and break the weathered surface. Wait for some stormy weather to wash off most of the debris. Re-clean briefly once really dry to get remaining dust off. Climb. This will require two/three visits.

[mark20]

Agree with the above. Big dustpan type brush when damp and plenty of chalk to kill any remaining green
Smokers toothbrush to re-clean on a dry day

[Bonjoy]

Just damp enough to hydrate/fluff-up the algae(the green stuff mostly isn't lichen) is best. It'll then brush off pretty cleanly. If it's fully wet it'll tend to smear around unless you have a load of extra water with you to rinse down the rock and brush between scrubs.
Fiend's comment about not overbrushing damp grit is true on soft bits, less so on hard bits. If it's mostly scrittle I.e. loose grit you're trying to clear then you're better cleaning it when it's dry. If it's uncleanably scrittly/soft and is likely to erode with use then you might consider stabilising, but that's a whole different topic.