The shotter is obtained by
broken porphyric rocks (0-4mm). The smallest fraction is removed by
sieving with an IKEA sieve with a mesh size of 1mm.
The retained material is then sived through a self made sieve, mesh
size 2 mm. (Two metal gauzes are put onto each other, leaving a mesh
width of about 2 mm). We obtain a grain of 2 to 3 mm which is the
The smallest grains and powder can be used as HO shotter or used
instead of the joint filler to make concrete walls.