A high quality pigmented water-based primer with good hiding power and excellent penetrating qualities suitable for application to dry, raw cement plaster, fibre cement and cement bricks with superior resistance to alkali attack and efflorescence. This primer is also suitable for use on gypsum plaster (i.e. rhinolite) that dries with a firm surface (not above powdery residue). It can be overcoated with a full range of Excelsior water-based products. This product has a low VOC compared to typical solvent-based plaster primers and it is easy to clean up painting equipment with water.