How can the setting time of alginate be prolonged?

The setting time of alginate can effectively be prolonged by using cold water. When alginate is mixed with cold water, the rate of the chemical reaction that leads to the setting process is slowed down. This is because cooler temperatures decrease the kinetic energy of the molecules involved in the reaction, which consequently slows the rate at which the alginate particles interact and form the gel structure.

Using warmer water, on the other hand, would accelerate the setting process, leading to a quicker gel formation. Adding more powder could increase the viscosity of the mixture but doesn't necessarily extend the setting time as it may actually lead to a faster set due to a higher concentration of alginate particles. Stirring more vigorously would introduce air into the mix and can also increase the heat of the mixture due to friction, ultimately leading to a faster setting time. Therefore, cooling the water will yield the desired prolongation of the alginate's setting time.