Abstract: The present invention relates to an apparatus and method for injecting sealant material into the corners of an insulated glass assembly suitable for use in manual and automated production. It has been found that significant saving in both time and material can be achieved by only sealing the corners of the assembly, particularly using the automated method and apparatus. The apparatus includes a pair of wiper blocks each having a surface for abutting an edge of a glass assembly arranged in substantially perpendicular configuration to each other, adapted for converging and diverging reciprocal movement from an adjoining position for molding a square corner to a separated position for wiping smooth the surface for the injected sealant material. A nozzle is positioned between the wiper blocks for injecting sealant material into the corner area and retracting in concert with the converging movement of the wiper blocks.