This study investigated the effect of storage period on dimensional change and deformation of stone models to determine an acceptable period of alginate impression storage in a sealed bag after spraying with disinfectant solution. Two alginate impression products: Aroma Fine DFIII and Alginoplast EM, characterized by greater or smaller contraction in 100% relative humidity, were used. The impressions were sprayed with 1% sodium hypochlorite or 2% glutaraldehyde solution and then stored in sealed bags. The storage periods were 1 hour, 2 hours, 3 hours, and 4 hours. The sectional profiles of the stone models obtained from each impression were measured using a three-dimensional coordinate measuring system. The results indicated that the impression characterized by greater contraction in 100% relative humidity should not be stored for even 1 hour, and that storage for up to 3 hours of the impression characterized by smaller contraction was clinically acceptable.