When hand-mixing is used, clinicians mix zinc phosphate cement to consistencies which allow proper seating of restorations. Slump tests have indicated that the same two preferred consistencies (one for cementing a single unit restoration, the other for cementing a multiple unit restoration) could be obtained at different slab temperatures for three cements by mixing to certain powder-liquid ratios which were different for each cement. Each cement could be repeatedly mixed to the preferred consistency by using the appropriate powder-liquid ratio. The compressive and tensile strengths of the cements varied, although mixed to the same consistency. Selection of a cement for clinical use should be based on its strength properties when mixed to a preferred consistency.