Boral Black Oxide is added to pure cement to create Black shaded concrete, mortar, grout or render. Lighter shades are created by adjusting the quantity of oxide to the mix. 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. Please note, always conduct a test sample before mixing mortar to ensure adequate colour is achieved