Alternating currents are normally used for Gas Tungsten (TIG) welding of aluminum in order to remove surface oxides and to improve weld cosmetics. However, the processing competitiveness is weak since weld penetrations beyond 3 mm cannot be reached under normal operating conditions. One way to improve weld penetrations is to increase arc specific power on the base plate. With this in view, we have developed a flux-bounded coating (FBTIG technique) for aluminium, which gives very promising results on weld penetrations. In 5086 alloys, 6 mm thick welds are easily obtained by applying a silica coating around the joint. The effect of different process parameters such as welding current, flux gap and travel speed has been investigated on 5086 and 1050 aluminum plates. This paper will discuss the experimental results on process parameters and arc observations to explain possible factors contributing to enhanced penetrations observed in FBTIG welding process.