Single-component, solvent-free, hygro-hardening polyurethane primer with very low emission of volatile organic compounds (VOC) for waterproofing cementitious screeds. If after applying F.24 POLIPRIMER MONO a cementitious levelling coat is to be made, apply a quartz dusting on the newly treated surface in order to create an adequate bonding bridge, removing the excess not anchored after 36 hours.