(b)1 part by weight of vegetal carbon dust produced from beech wood with a particle size of 0-100 μm, a4c0
(b)1 part by weight of vegetal carbon dust produced from beech wood with a particle size of 0-100 μm; a3c0
(b)1 part by weight of vegetal carbon dust (beech wood) with a particle size of 0-100 μm, a0c0