Final answer:
The best way to prolong the working time of polyvinylsiloxane is to decrease the temperature, as cooler temperatures slow down chemical reactions, thereby extending the material's setting time.
Step-by-step explanation:
The best way to increase the working time of polyvinylsiloxane (PVS) is to decrease the temperature. This is because chemical reactions, including the setting of PVS, generally occur more slowly at lower temperatures. If you increase the temperature, the setting reaction of PVS will accelerate, thus reducing the working time. Conversely, decreasing the temperature will slow down the chemical reaction, giving you a longer working time. It's similar to how sugar dissolves more rapidly in hot water because of increased molecular motion at higher temperatures affecting solubility. Hence, increasing the mixing time or decreasing it will not directly affect the setting time as much as temperature control will.