Abstract: Thermal properties of green sand and three insulating materials-pearlite, foamed plaster and ceramic wool are determined by an unsteady state method involving melting and casting. An equation for insulated riser design is developed, based on solidification characteristics of sand casting. Tests are conducted on pure aluminum cube castings and a satisfactory agreement between the calculation and experimental determination of the riser size has been found: the riser insulated with pearlite or foamed plaster is about one seventh and that insulated with ceramic wool, is one eighth of the conventional. In addition, a prediction of the benefits gained from the use of insulated risers is determined by means of theoretical analysis. It is shown that use of insulated risers for alloys with narrow solidification range may give a substantial increase in productivity and casting yield, and an obvious effect in saving of the cost of melting and riser removal as well.