The parameters that promote the formation of surface detects on multi-phase polymer systems during injection molding are not yet clearly understood. The objective of this work is to establish the influence of composition, particularly the role of rubber, on the rheological properties of such multi-phase systems and relate that to variations in gloss that appear on the surface of ASA and PC/ASA blends. Analysis of morphology by micro-thermal analysis (muTA(TM)) in combination with oscillatory rheology, time-temperature-superposition (TTS), creep recovery and PVT testing revealed distinct trends of surface gloss with each material's viscoelastic behavior and surface finish. It has been shown that influential properties such as rubber content, particle size and distribution, molecular weight, viscosity ratios and the degree of acrylonitrile mismatching play key roles in each material's rheology, developed morphology and subsequent trends in surface gloss after injection molding.