What happens to an alginate impression when it is stored in water?

When an alginate impression is stored in water, it tends to absorb water. Alginate is a hydrophilic material, meaning it has an affinity for water. When placed in water, the impression can swell as it takes on moisture. This ability to absorb water can lead to dimensional changes in the alginate, which can compromise the accuracy of the impression. The increased moisture content may also affect the mechanical properties of the alginate, making it softer, which can result in loss of detail and strength over time.

Understanding this property is crucial for dental professionals, as it underscores the importance of proper storage conditions for alginate impressions to maintain their integrity until they can be cast in a suitable dental material.