What are the differences between kinds of sandpaper?

There are four different kinds of sandpaper, or abrasives that are used in the woodworking industry; Aluminum Oxide, Garnet, Silicon Carbide, and Ceramic. Most often,woodworkers use aluminum oxide and garnet sandpapers.

Aluminum Oxide is one of the most common woodworking sandpaper. It has a high degree of friability. This means that when heat and pressure are applied it breaks up into smaller peices, or fragments. This is a desirable property because when Aluminum Oxide is used, it creates new sharp edges. This allows aluminum Oxide to outlast other sandpapers.

Garnet, the second most used sandpaper, is actually a natural abrasive (ie real sand) that is still commonly used in woodworking. It is not friable like Aluminum Oxide and tends to wear out a lot faster. Depending onwhat you are sanding, sometimes you do not want a sandpaper that is friable. Garnet will produce a smoother surface than aluminum oxide of the same grit number. It will cut slower than it aluminum oxide however. Garnet is also a good choice for a final use sand paper. It has the tendency to burnish, or seal off a wood’s grain. This allows pigmented stains to penetrate woods such as birch, pine, or lauan, more evenly.

Silicon Carbide is good for cutting harder materials like as metal, plastic, and fiberglass. Silicon carbide is a friable abrasive but wood is not hard enough of a material to fragment its surface so it tends to wear out more quickly than Aluminum Oxide.

Ceramic is the most expensive of the sandpapers, it is also the hardest of all of the sandpapers commonly available. It is generally available in only the coarser grades for rough wood removal. The most common use for ceramic sandpaper is shaping and leveling of wood. Ceramic sandpaper is used primarily for sandpaper belts.