Recommended to use weight to measure grits. You will save money.
60/90SILICON CARBIDE – 1 ounce per pound of rock
220 SILICON CARBIDE – 1 ounce per pound of rock
600 SILICON CARBIDE – .5 ounce per pound of rock
Micro-Alumina Polish – .5 ounce per pound of rock
Silicon Carbide is one of the hardest-known materials with a mohs scale hardness of 9+. Most rocks have a hardness of 7 or less. When crushed, silicon carbide breaks into angular-shaped particles with sharp points and edges. This gives it an effective cutting and grinding ability when it is caught between tumbling rocks in tumbler barrel. It is one of the least expensive methods of polishing rocks and gems.
Most of the tumbling done in a rotary tumbler follows a four-step grit and polish, 7 days approximately per grit. The grits used are typically begin with coarse 60/90, 80 or 100 grit, followed by medium 150 to 220 grit, followed by fine 500 to 600 grit, and finished with a rock polish such as Micro-Alumina Polish.
Most of the tumbling done in vibratory Tumblers follows a three-step process, 3 days approximately per grit, that includes medium 150 to 220 grit, followed by fine 500 to 600 grit, and finished with a rock polish such as Micro-Alumina Polish.
It is recommended after cleaning you rocks and barrel to use a tablespoon or so of shave ivory bar soap. Other soaps will not hurt the rocks, but could be hard on the barrel. Overnight in a rotary tumbler, 4 hours of more in a vibratory tumbler.