An exemplary method for set retarding the surface of a mortar or concrete material, comprising applying to the surface of a mortar or concrete, or to the inner surface of a mold for forming the mortar or concrete, a hot melt coating composition which is heated to assume a flowable or sprayable form, and allowing the hot melt coating composition to cool to ambient temperature whereby the composition forms a solidified membrane, and thereafter removing the membrane. Preferably, the hot melt coating composition contains at least one agent operative to retard the setting of the mortar or concrete, and optional finely divided particulate materials, light-reflective pigments, or mixtures thereof.