Aluminum oxide (anti-slip aggregate)
Aluminum oxide is the hard-wearing grit of choice for slip-resistant floor coatings: with a Mohs hardness of 9, it keeps its edges long after softer aggregates have worn smooth.
Aluminum oxide (alumina, molecular weight 101.96 g/mol) is an extremely hard ceramic material with a Mohs hardness of 9 and a density of about 3.9–4.0 g/cm³. For coatings it is mostly used as fused alumina grit: brown fused alumina, the tougher general-purpose grade, and white fused alumina, the higher-purity, lighter-colored grade. Grit is sized by standard grading systems, with lower numbers meaning coarser particles.
Aluminum oxide grit is chemically inert and generally not classified as hazardous, but handling and blasting create dust. Use dust control and respiratory protection. One advantage over silica sand is that aluminum oxide does not contain crystalline silica, a major respiratory hazard in sand blasting.
It depends on traffic, footwear and cleaning. Coarser grits give more traction but are harder to clean; finer grits suit barefoot and food areas. Follow the coating manufacturer’s recommendation and test slip resistance where required.
Aluminum oxide is harder and holds its texture much longer, so it is preferred for heavy traffic. Sand is cheaper but wears smooth faster, and blasting with it raises crystalline silica concerns.
Broadcasting into a wet coat and then locking it in with a topcoat gives the most durable, aggressive texture. Mixing fine grit into the topcoat gives a more uniform, easier-to-clean finish.
