PVS (Polyvinyl siloxane) materials are hydrophobic which may encourage formation of surface voids affecting the surface hardness and accuracy of resultant cast. The wettability of dentine surfaces by impression materials depends on the hydrophilicity and viscosity of the material. Surfactant applied to an impression may reduce the number of voids in resultant cast or die. With the above background the present study was aimed to investigate the changes in the surface hardness of an investment material poured in polyvinylsiloxane moulds following the application of three brands of commercially available topical surfactants. A precisely machined steel cylindrical master model was made 20mm in diameter and 35mm in length for the fabrication of PVS moulds. A precisely machined casting ring former 40 mm in diameter was made and the master model was mounted centrally on a plastic sheet. PVS duplicating material, Ecosil (Dentaurum) was mixed according to the manufacturer’s instructions and poured into the casting ring former to create four moulds. Fifteen specimens were poured into each of the moulds for each model material/ surface treatment combination, yielding a total of 60 specimens for testing. Brinell hardness test was performed using a universal testing machine and the results were compared using one way ANOVA and Post-hoc Tukey’s test. Aurofilm greatly increased the surface hardness of investment material (BHN-90) when compared to the control group while the surfactants Debubblizer and Waxit decreased the surface hardness of investment material when compared to the control group. The surfactant Aurofilm was found compatible with both PVS duplicating material (Dentaurum) and investment material (Bellavest-T). The surfactants Debubblizer and Waxit were found incompatible with investment material.