Guide to Abrasive Sizes

There is a potentially baffling number of different ways of measuring the sizes of abrasives. It can sometimes seem that no two suppliers use the same terminology. The most sensible way would be to give the micron size so that direct comparisons can be made.

Elutriative time is the time a particle will take to settle in a 1 metre column of water. Elutriation is a simple way of ensuring that abrasives do not contain larger-sized particles.

Mesh Decimicron 'M' Size in microns Elutriative time
60 - M60 293 -
80 - - 185 -
100 - M100 148 -
120 - - 123 -
180 - M180 86 1 min
220 - - 73 -
280 - - 39 -
320 - - 37 -
400 - - 34 -
600 - - 25 -
- 225 - 22.5 -
700 - M302 22 5 min
- 175 - 17.5 -
850 - M302½ 17 10 min
1000 - M303 15.5 20 min
- 125 - 12.5 -
1300 - M303½ 11 40 min
- 95 - 9.5 -
1800 - M304 8 60 min
3000 - M305 5 -