Ask the Expert

QUESTION:
What are the most common grains for sanding wood?

ANSWER:
Two of the most common grains used to sand and finish wood are Silicon Carbide (S/C) and Aluminum Oxide (A/O). Silicon Carbide is an extremely hard grain. The hardness of Silicon Carbide is second only to a diamond according to Mohs hardness scale as Silicon Carbide has a hardness of 9, a Diamond has a hardness of 10. Even though Silicon Carbide is extremely hard, it is also very brittle which results in the grains fracturing at a quicker rate than Aluminum Oxide grains. The Silicon Carbide grains however are very friable, meaning they re-sharpen each time they fracture to expose a new sharp grain. The grains also break down very consistently. It is because of these characteristics that Silicon Carbide is often used for the final finish of wood and, most commonly, between coats of finish. Even though the life of the grain is compromised due to the quick breakdown of the grain, it does present a very fast cut with less likelihood of sanding through the finish coat.

Within the Aluminum Oxide range, there are many different types of grains with the most common types being white, pink and brown Aluminum Oxide. Uneeda Enterprizes employs the use of all three depending on the product and grit. Brown Aluminum Oxide is the most durable where White Aluminum Oxide is the least durable but will yield the finest finish due to the rate at which the grains re-fracture.  Many times White Aluminum Oxide can leave as good a finish as Silicon Carbide yet will yield more abrasive life. 

In addition to these four basic grain types there are heat treatments, ceramic coatings and other features that can be added during the grain manufacturing process that also differentiate the grains.

Please feel free to email us at sales@uneeda.com or call us at 800-431-2494 for information.

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