And there is absolutely no reason to tumble the rouge unless moisture has caused some clumping, and grading with water, which should be done anyway, will take care of that.

Unlike the ground black iron, red rouge is molecular in size and is not bound as magnetic crystals. One cannot grind rouge down to a smaller size. It is only the question of impurities to which tumbling is not an answer but water grading is.


Cheers,
-Rick