Magnesia: powdered or liquid chalk bags for rock climbing

Magnesia is magnesium carbonate, which is found in nature in a mineral state. It is used in sports such as gymnastics, weightlifting and climbing to prevent the hands of sportsmen and women from slipping when they sweat. In climbing, it therefore provides grip, absorbing moisture and improving adherence, in order to optimise the climb.

Climbing magnesia: what exactly is it?

Just like the rope, harness, climbing helmet and climbing carabiners, chalk is an indispensable part of the equipment of any self-respecting climber. It is magnesium carbonate which comes in powder or liquid form and to which silica is sometimes added. There are 4 main types of magnesia:

• Powdered magnesia is the one most frequently found in sachets or in the form of a ball.
• Liquid magnesia is actually liquid magnesia to which alcohol has been added. A thickener or resin can also be added.
• Chalk ball magnesia is, as the name suggests, a rag ball containing powdered magnesia, which is opened and closed with a cord.
• Chalk block magnesia is of the same composition as conventional powdered magnesia. It is used by crushing small pieces between the fingers.

Note that some climbers use rosin, called "pof", which is ground into powder and stored in a cloth. This is actually pine resin crystals that improve the grip of the fingers in a very effective way. Pof is mainly used for bouldering and its name comes from the noise the rag makes when climbers hit it on the areas of the rock they want to increase the grip.

What is the use of magnesia?

Magnesia allows climbers to dry their fingers when gripping holds and thus avoid slipping. It has hygroscopic properties, i.e. it attracts water molecules and effectively absorbs sweat and moisture. Its use therefore allows climbers not to be stopped in their ascent because of grip problems and to progress in complete peace of mind. This is why they all have a chalk bag attached to their waist.

Powdered or liquid magnesia: which type to use for climbing?

Both types of magnesia have their advantages and disadvantages. The powder version is the most commonly used for climbing. It can be bought in large bags and carried in a magnesia bag, also known as a "pof bag", which attaches to the harness and has the advantage of leaving both hands free for the climber. The chalk bag can be rectangular or cylindrical in shape and is easily opened and closed with a cord. The main disadvantage of powdered magnesia is that it is very volatile, which makes its use in climbing gyms problematic.

Liquid magnesia avoids this problem and is therefore particularly practical for indoor use. It is also much less messy, both for holds and for the ground. On the other hand, it has the disadvantage of drying the hands (due to its alcohol concentration) and requires both hands to be free to use it.