Three glass-ionomer cements, mixed at room temperature and cold mixed, were evaluated for film thickness at different powder to liquid ratios. Film thickness was measured at 1, 2, and 3 minutes after mixing was initiated. The relative accuracy of the manufacturer's volumetric dispensing systems was also measured. For two of the three cements tested, cold mixing significantly reduced film thickness at extended working times and increased powder/liquid ratios. The results suggest that the appearance of the cement surface indicates setting in advance of film thickness and that cold mixing should be routinely employed.