Bouldering techniques - cleaning holds & brushing
The two main reasons you'll need a toothbrush when out climbing are: to ensure that holds are free from dirt and to remove excessive amounts of chalk.
Keeping holds free from a build-up of chalk will improve the friction of the rock - too much chalk clogs the rock's surface and gives a slippery feel to the holds. Brushing away excess chalk is normally done with a toothbrush; the narrow head profile means that most holds, including small pockets, can be cleaned effectively. Stiff-bristled brushes work well as they can be used to break up accumulated chalk without 'scrubbing' the hold.
Brushing away excess chalk is normally done with a toothbrush
While chalk washes off problems in the rain, many sheltered holds never, or rarely, get wet although they do absorb the moisture within the atmosphere. With such holds the chalk may eventually need to be washed from it using a brush and some water, the chalk becomes slippery. Remember though, rock is often weakened and so holds are more prone to break when wet.
Commonly, dirty holds are brushed with a wire brush although such brushes can scratch the rock, in some instances improving holds. Generally, a stiff bristled house brush will work as well and without damaging the rock. Most rock types are actually quite soft and are easily damaged by over enthusiastic brushing. Even gritstone is soft under its abrasive outer layer (this can be clearly seen at the Bridestones.
Clean holds provide a better grip but don't use wire brushes as these will damage the rock and the holds.
A toothbrush is normally used for cleaning chalk from holds, but again a stiff bristled one works best. Two approaches can be used here: Either the bristles can be used to break up the caked chalk, so it can be blown away, or a conventional brushing action can be used.
Which you choose depends upon the hold itself. Holds generally have an optimum level of chalk but this differs between holds and rock types.
The other useful complement to a toothbrush is an extension pole so that high holds can be cleaned easily (without resorting to human pyramids). Bear in mind that awkward to reach holds are more likely to suffer from a build up of chalk. Some people have attached long 'blow tubes' to their extension poles that allow them to blow the chalk from the hold once brushed.
A further option, although more unwieldy, is the use of a ladder to stand on, it is best for roadside crags and is rare in this country. At Fontainbleu many locals, rather than brushing holds, actually use the tail end of a rag to remove excess chalk.