Silicon carbide is a sharper and harder grain than aluminum oxide, but silicon carbide is less durable because it is brittle and has a narrower shape that wears out faster. Due to its razor sharp grains, silicon carbide will have no problem easily cutting glass, plastic and metal under light pressure. However, hardwoods and metals will present more challenges. Regardless of sanding wood or metal, silicon carbide and aluminum oxide can be effectively combined on the same sanding project, especially in carpentry applications.
Silicon carbide sandpaper is a blue-gray, black, or charcoal synthetic paper, often with a waterproof backing.
It can be used on wet or dry surfaces.
Its crumbly surface self-sharpens on harder materials, making it the best sandpaper for metal and plastic.
It is ideal for polishing or use between top coats.
A common rule of thumb for sanding is to use a lower number coarse grit first before moving to higher number grit to add a finer touch. For example, on your average three- or four-head sander, you can start with an 80-grit wide belt to cut and calibrate the sanding element, focusing on achieving the preferred thickness.
When sanding you never want to skip more than one grit, so the next grit would probably be 120. Grits 80 and 120 are likely to be aluminum oxide, but your final 180 grit should be silicon carbide. , depending on whether your goal is to achieve the best finish without worrying too much about the longevity of the belt. This strategy artfully takes advantage of the durability of aluminum oxide, while using the sharpness of silicon carbide to navigate to a superior finish. For the finish, nothing better than silicon carbide because it is very tolerant. The silicon carbide product will produce a remarkably uniform finish.