How Does a Stone Polisher Work?

Introduction

A stone polisher is a machine that uses an abrasive substance, water and friction to erode stones. Through a mechanical process it mimics nature where water erodes stone. River stones along a beach are smooth and shiny due to natural polishing. A stone polisher does the same work in a more controlled way.
There are two main types of mechanical stone polishers: rotating and vibrating. Rotating polishers polish and round down edges, while vibrating polishers only polish. Within the vibration category is the ultrasound stone polisher which is like the device used by a jeweler to clean jewelry.
To give a gloss shine, polish powder is used at one point during the polishing. Titanium dioxide, cerium oxide and tin oxide are three main types of polish used in stone polishers.
The abrasive substances a stone polisher uses are various levels of silicon carbide grit and silicon sand. The various coarseness levels are used at different times during the polishing process.

Rotation Stone Polisher Diagram
Rotation stone polishers use a horizontal barrel to weather rocks into smoother shapes. The barrel rotates slowly, with the abrasive substance and the stones rubbing against each other. The reason why the barrel rotates slowly is because the rocks can then roll over each other carrying grit with them. This allows for a more even distribution of grit.
The rocks also hold to the sides of the barrel and then "tumble" down over each other. The tumbling adds to the friction and wearing down of the stones.
A rotation stone polisher uses four steps to polish stones. First, a coarse grit to shape the stones, second a finer grit to get leftover shape oddities and nicks, third, a silicon sand to get a more finished smoothness. The forth step uses the polish instead of grit, sometimes with plastic pellets to cushion the stones, and spread the polish. On the whole, a month is needed to complete all the steps.

Vibration Stone Polisher Cross Cut
Vibration stone polishers shake the stones; they don't tumble them like a rotation polisher.
The vibration process doesn't round the stones like a tumbler stone polisher does. And the stones are in continuous contact with each other. That means that there is more friction used and so less time is needed to polish the stones. In fact it takes half the time as a rotation stone polisher. While the tumbler takes a month the vibration polisher is done in two weeks. Also, vibration polishers use less water and grit. However, the grit is changed more often.