In order to clean the balls from the undesired materials, that can not be removed by normal washing, one of the routes may be followed:

1- Physical cleaning: in this route, cleaning is achieved by mechanical effect obtained by milling a hard material that abrades the undesired materials.

2- Chemical route: in this route the balls, as well as the jar, are washed with a solvent that can dissolved the undesired materials without harmfulness the balls.

Using ultrasonic energy is the best approach.

As Imad suggest, in chemical route, you can fill the jar with just balls and cleaning solvent and start milling for 1-2 hours later on through away the solvent and do acetone/ethanol cleaning for the last time.

I agree with Dr. Akeshwar Singh Yadav's answer

Regards

G.A.Khater

Akeshwar Singh Yadav

please, could you explain the steps of cleaning balls and jars in more detail?

For general cleaning of agate balls or grinding jars it is often advisable to mill for a short time some quartz sand, coarsely crushed uncoloured container glass, or small broken pieces of window glass. Pure cellulose absorbing paper wetted with water, ethanol, methanol, acetone, or isopropanol; may help to complete cleaning, and may be found sufficient by itself. Specific cleaning may be required for some contaminants.

Did anyone in the planetary mill use balls of different sizes at the same time?

I agree with Dr. Carlos

Best regards

Dr.G.A. Khater

Srdjan P Petrovic : it is not recommended to use balls of different diameters at the same time - I suspect that such a practice would either endanger the integrity of the balls due to varying impact forces, or it would add a level of uncertainty as to the end-size of the particles produced (non-homogeneous). To be safe, best practice protocols indicate that you should start from large-diameter balls (loading, size, and material relative to your processed material), and move down in ball sizes consequently until you arrive at the refinement you need.