A variety of synthetic minerals are used as sanding grains or abrasives, but the two main synthetic minerals for sanding wood are aluminum oxide and silicon carbide. We add that zirconium is also used as a modern trend.
Aluminum oxide (AL₂O₃) is hard, strong and can withstand high sanding pressure. Aluminum oxide (also corundum) is characterized by less sharp edges and irregular shape. It can be used for both soft and hard wood. Because sanding results are tougher than when sanding with silicon carbide, then aluminum oxide is more suitable for calibration and stock removal of material. Aluminum oxide withstands high pressure at high sanding temperatures.
Silicon carbide (Sic) is the hardest abrasive grain. Silicon carbide has a different shape and different cutting properties than aluminum oxide. It is characteristic that a single grain is sharper and several sharp edges can be used at the same time because the grain is better shaped. At the same time, silicon carbide is more fragile and brittle and cannot withstand high sanding pressure. High pressure crushes the grain and shortens the overall life of the sanding belt. Silicon carbide cuts the material more clearly and gives a better (fiber-free) finishing. Suitable for soft wood intermediate sanding, hard wood finishing, for surface finishing of MDF and other plates.