How can the setting reaction of alginate impression material be ACCELERATED?

Correct answer: C. Mix with warmer water

• A. Cooler water DELAYS the set — the opposite of what is asked here.
• B. Spatulation time affects mix homogeneity and incorporated voids, not the fundamental rate of the gelation reaction.
• C. Correct. WATER TEMPERATURE is the practical clinical control over alginate setting time. Warmer water accelerates the chemical reaction and shortens working/setting time; cooler water slows it and lengthens working time (useful for a large or difficult arch, or in a hot operatory).
• D. Altering the powder-to-water ratio changes viscosity and materially degrades the strength, tear resistance and dimensional accuracy of the impression. It is not an acceptable way to control set time.

Note: Alginate must be poured within 10–15 minutes to avoid syneresis (fluid exudation) and imbibition (water uptake), both of which distort the impression.