Oxide Medium Brown 660 4kg Boral Blue Circle, add this Medium Brown coloured oxide to pure cement to create Black shaded concrete, mortar, grout or render. Make lighter shades by including littler measures of oxide. Oxide should to be included by volume not weight and the amount of oxide utilized relies upon the amount of cement in your mix, not on different components of the mix, for example, sand or aggregate – see package for further directions.