<prompt> A cast is poured with polysulphide impression material, but details are not achieved in cast. For achieving that what should be done?Adding surfactant to gypsumMixing surfactant to impression materialSpraying water to gypsumSpraying water mixing surfactant to gypsum  <response>: Absence of fine details in cast poured with polysulfide impression materials indicates its hydrophobic property.A nonionic surfactant can be added to the impression materials in the manufacturing process to produce a degree of hydrophilicity to the surface of the material.The beneficial effect of optimal surfactant mixing at the time of manufacturing is not reduced by rinsing the impression prior to pouring, so fine details can be achieved on cast too. 