soil

The original sample block has been pre crushed to < 1 cm size manually (with a hammer; inside a plastic bag). Afterwards, start size of sample has been appropriate for a comminution with a Mortar Grinder.

After 10 minutes of grinding, sample starts lightly to stick to the mortar. The scraper is detaching flat chips which will be fed to the pestle again. This uses to happen after the majority of particles reached a fineness of < 30 µm. Interacting forces between fine ground particles will become bigger as their own g-force. Therefore, particles will stick to each other and become compressed by the pestle. These clusters of particles also contain bigger particles which will not be ground any further.

For a further reduction of particles size, we recommend grinding in suspension. Because the desired fineness is already reached, we aborted the grinding process without adding of water (as described