As a manufacturer of concrete products one is often faced with request for black concrete – not just anthracite. Permanent supposedly black coloring is obtained only with Iron Oxides or with Carbon Blacks. Advantages and disadvantages are found in both variants.
he Iron Oxide, the safe version of a black coloring unfortunately, does usually not achieve the desired color intensity, even at high doses, despite further developments of some products on the market. Anthracite colors are avaiable that are stable and durable.
With the use of Carbon Blacks a deeper blackening can be achieved. Due to only mechanical anchoring in the concrete, the blackness and the durability are extremely dependent on the particle size and the raw material mix for the production of carbon. Necessary for the anchorage would be a high particle size (at least 70 nm). The particle size increases inversely proportional to the color strength. The commercially available products are 70 nm up to almost 300 nm in size.