rose quartz / aquamarine

Because 20mm Ø balls might be too weak for a grinding of up to 10mm start size, we used 30mm Ø balls for pre grinding in this trial.

Now balls can be changed to 20mm Ø (see result 2).

In dry grinding, sample starts sticking after totally 10 minutes. A longer dry grinding time is not recommended.

The sample started sticking to bowl and balls. This uses to happen after the majority of particles reached a fineness of < 20-30µm. Interacting forces between fine ground particles will become bigger as their own g-force. Therefore, particles will stick to each other and just become compressed by the used grinding balls. These clusters of particles also contain bigger particles which will not be ground any further too.

A better endfineness can only be achieved by grinding in suspension.