Extruded klinker facing bricks fired at a higher temperature and in a reducing atmosphere, i.e: with little oxy-gen. The iron compounds which are transformed into reddish coloured ferric oxide in oxygen firing, become ferrous-ferric or ferrous oxides with a hazel-coloured, brown, grey, black or ochre colour depending on the degree of oxygen.

The controlled programming of the oxygen reduction combined with the right mixture produce a wide range of compositions to give each project a unique appearance with its own special sheen.