When mixing zinc phosphate cement, a cool, dry slab will _______ the setting time.

When mixing zinc phosphate cement, using a cool, dry slab will decrease the setting time. The temperature of the mixing surface impacts the exothermic reaction that occurs as the cement sets. A cooler slab helps to dissipate heat more quickly, thus leading to a faster setting process. Conversely, a warmer slab would allow heat to accumulate around the materials, potentially prolonging the setting time as the reaction is slowed down. Therefore, the combination of a cool surface and a dry environment collectively contributes to a reduction in the overall time it takes for the cement to set effectively.