A variety of Wolverhampton Abrasives' standard abrasives can be used for flooring applications. They can be either premixed with the concrete so they are through the complete floor, commonly referred to as 'trowel in' or can be spread on the top , commonly referred to as 'dry shake'. Special sized grades of abrasive can be supplied to give the optimum surface finish. The bulk of flooring materials supplied are based on either iron silicates or ferro silicons. The iron silicate is available in either water cooled or air cooled format, the water cooled is only available in sizes up to 4mm , whilst the air cooled is available up to 30mm. The air cooled is harder and has a different crystalline structure to the water cooled. The hardest material supplied is ferro silicon which is a metallic alloy, having a large portion of bonded iron. It is generally specified where a particularly hard wearing surface is required. Aluminum oxide can be used in flooring applications; but due to its high cost its application is mainly limited to shaking on the surface for its non slip properties.