[Mixing time of zinc phosphate cement (author's transl)]

Since the mechanical and chemical properties of zinc phosphate cements are variable under varying conditions, it is very important to obtain optimum conditions of manipulation. Many authors have written about the effect of the powder-liquid ratio, room temperature and humidity, but there are few reports on mixing technique. Consequently, we studied the influence of mixing time on the properties of the cement. Mixing time was 45 seconds, 90 seconds, 180 seconds, and 270 seconds. The results obtained were as follows. 1) The shorter the mixing time, the shorter the time to reach the maximum temperature and the higher the temperature. 2) When the mixing time was long, the setting time was prolonged. 3) Compressive strength appears the highest at the 90 seconds mixing time. In both cases, when mixing time was longer or shorter, compressive strength decreased. 4) Hardness showed the same tendency as compressive strength, and also the 90 seconds mixing time had best results. 5) As the mixing time increased, film thickness increased remarkably and was inadequate for the use of cementing.