Iron oxide black and carbon black serve different needs. Carbon black provides a pure, deep black with very high tinting strength — it is preferred when maximum blackness and the lowest possible addition level are needed. Iron oxide black provides a softer, blue-toned black with better alkali resistance, higher thermal stability (300°C vs 300°C for carbon black), and is non-conductive vs slightly conductive carbon black. For concrete colouring and cement-based systems, iron oxide black is preferred because it is more stable in alkaline environments. For maximum black depth in paints, carbon black is more cost-effective.
