Sanding Rubric

Abrasives 

This is the "business end" of the paper. Common minerals include:

• Aluminum Oxide: The brown/tan all-purpose standard. It's tough and long-lasting.

• Silicon Carbide: The black, sharp stuff often used for "wet sanding" or finishing metal.

• Garnet: A natural mineral (reddish) that produces a very smooth finish on wood but wears down faster.

• Ceramic: The powerhouse. It’s extremely hard and stays sharp by fracturing into new sharp edges as it wears.

Imagine a sifter (a screen) with a 1-inch by 1-inch square frame. The "grit" is determined by how many holes are in that square:

• 60-Grit: The screen has 60 openings per linear inch. To fall through those holes, the grains have to be relatively chunky.

• 220-Grit: The screen has 220 tiny openings per linear inch. Only microscopic dust-sized particles can pass through.