POROSITE                  DIAM EN MICRON                USAGE

0                                        161 A 250                        TRES GROSSIER

1                                        101 A 160                         GROSSIER

2                                         41 A 100                             MOYEN

3                                          17 A 40                                FIN

4                                           11 A 16                             TRES FIN

5                                          1,6 A 10                             ULTRA FIN