<prompt> Impression plaster is:Less compressive than alginateMore compressive than alginateAs compressive as alginateMore compressive than hydrocolloids  <response>: IMPRESSION PLASTERImpression plaster is a β-calcium sulfate hemihydrate used at a waterpowder ratio of approximately 0.5 to 0.6. Its fluidity makes it suitable for making impressions of soft tissues in the uncompressed state, a characteristic of mucostatic impression material. Key concept: Impression plaster is less compressive than Alginate.Ref: Phillips 12 ed page no 177 