I'm in love with Silicone Carbide Grit. It is in my opinion the most underrated, best value for money, least used, cheapest and versatile tool on the market. It has many uses in lamp work, cleaning bead holes, and cold work to name but a few. This article will explore its properties and use in cleaning and grinding cabochons.

The Facts

Silicone Carbide Grit, also known as carborundum , is a compound of silicon and carbon. It occurs in nature as the extremely rare mineral moissanite. Silicon carbide powder has been mass-produced since 1893 for use as an abrasive.

In the arts, silicon carbide is a popular abrasive in modern lapidary due to the durability and low cost of the material. In manufacturing, it is used for its hardness in abrasive machining processes such as grinding, honing, water-jet cutting and sandblasting. Particles of silicon carbide are laminated to paper to create sandpapers and the grip tape on skateboards.

Silicone Carbide comes in different grades measured by number, the lower the number the coarser the grit.

A good initial grit for use with cabs is 180.

Cleaning and Grinding Cabs for Gluing or Setting

The purpose of cleaning and grinding is to remove the bead release in its entirety from the back of your cab, and take away excess glass. Removing bead release is extremely important if you intend to use glue and you want it to be effective and long lasting.

If you are setting your cab in a silver bezel you may want to remove some glass for the cab to sit lower in your bezel setting.

This before and after picture demonstrates what the Silicon Carbide Grit is capable of doing.

As the grit is highly abrasive, ideally, it should be used in a work area of its own; if it is not possible to have a work area set aside for this, ensure you thoroughly clean the surrounding surfaces, and if a cloth has been used dispose of it. The fine grit will remain in the fibres and cause damage to surfaces / objects when the cloth is used again.

Work Area Preparation

Apply a few layers of newspaper to your work surface.

Dampen the newspaper to ensure the glass stays in place.

Place the glass on the newspaper.

Add a small amount of grit to a flat piece of glass ( at least 4mm thick ) mix with a tiny bit of water and soap and place your cab in the centre of the grit and begin to apply a circular movement, rotating the cab on the grit. Listen to the noise it makes and you will get used to the sound it makes as the surface is worn away. Start with a courser grit (180) to remove bead release, work through the grits to achieve a finer more polished appearance.  

If you change grit size you must make sure that the coarser grit does not come into contact with the finer grit . Thoroughly rinse the cab and your hands before changing over.