A paper was presented at the 1986 SAE congress which accounted in part, for the variability in physical property performance within injection molded instrument panel carriers. As a continuation of that paper we developed two test molds to allow us to make a more fundamental examination of weld lines. One of these is a 76.2 × 101.6 mm flat test chip which is double gated to form a well defined weld line. This has enabled us to measure physical properties (including impact strength) of the weld line as a function of materials and molding conditions. Apparent color variations across the the weld line as a function of polymer morphology was studied as was paintability. The second mold, a boss testing tool, has allowed us to study the weld lines which form on the downstream side of these functionally important fastening points.