Bleau.info : Clean-up day : Magnesium

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Magnesium vs. pof in Fontainebleau

Bouldering is getting more and more popular as climbing discipline, so more and more climbers head to Fontainebleau. Unfortunately, many of them do not know about the local 'boulder ethics' in Font, and where they stem from. On this page, we therefore explain the do's and don'ts with respect to the use of magnesium and pof.

Magnesium is used by athletes in various sports disciplines to dry out hands. For climbers, magnesium is supposed to help to get more grip on rock surfaces (although there is research that claims that it hasn't got any impact at all, apart from a psychological one). However, it has a negative impact on rock surfaces, as it fills up the 'pores' of the surface. You can notice the effect on limestone, but for sandstone (as in Fontainebleau) the effect is disastrous. By overusing magnesium, holds in sandstone areas start to feel like soap bars. That's the reason why experienced Bleausards know that the use of magnesium should be limited as much as possible, and that boulders should be cleaned before and after climbing. Fanatic Bleausards will point to you in person if they feel that you overuse magnesium, and they will tell you that it is forbidden. Well, to quit magnesium is for many climbers as difficult as quit smoking is for many people...

Because of the negative effects of magnesium in Fontainebleau it is strongly adviced to use pof (= dried resin) instead, if necessary. Note however, that for other rock surfaces pof can be much more damaging than magnesium! In limestone, holds start to feel greasy due to pof, so in those areas you shouldn't use pof.
Most of the times, you can buy pof in Fontainebleau at the Decathlon in Villiers-en-Bière or at the weekend bus of SOeScalade. But it is much cheaper to buy it in a ballet / danse shop. Next, you take a large and firm textile fabric (for instance one that measures 60 by 60 cm.), and you put a large hand-full of resin in the middle of it, and tie it up firmly. If you hit a boulder a few times with this ball, you will notice the white residue that stays behind: this is resin dust that is responsible for additional grip on sandstone.
By the way, because people see climbers use pof on the boulders in Fontainebleau, some of them start mimicing this behavior by smearing magnesium on the rock surface. This is clearly counterproductive and doesn't lead to more grip!

With respect to the use c.q. misuse of magnesium we should also mention the so called 'tickmarks'. These are drawing with magnesium (or chalk) on the boulders made by (good) climbers to denote where holds are in difficult problems. We hope that, after reading the above, it is very clear that such drawings should be minimized as much as possible, and that they should be brushed away rigorously after climbing. In any case, it is much better not to leave any visual or other trace of magnesium on or around boulders, as this is something environmental activists will use as a reason to get climbing forbidden.

To conclude:

Do not smear magnesium on the boulders in Fontainebleau, but use pof if absolutely necassary.
If you aren't capable of leaving magnesium at home, dry your hands with it, but make sure no magnesium traces are left behind on the boulders.
Always clean the boulders after climbing with a non-metallic brush.
Be a nice law abiding citizen, and take your own garbage and the garbage of others with you from the forest.
Point out to others in a friendly way if they are misusing magnesium and explain them what they are doing wrong.