A new flux based on NaCl – CaCl2 – CaF2 – Na3AlF6 was developed for the gas welding of aluminium and its alloys. The flux was generated by the application of the Hadamard multivariate chemical composition model. The model uses a 8 x 8 matrix and a full factorial analysis to generate several compositions within given ranges of the constituent flux elements. Mechanical and field tests were carried out on weldments made with the flux. The tensile strength, Izod impact strength and hardness of the all – weld metal were 310MPa, 5.35J and 100BHN. The weld deposition efficiency was 90.3%.The new flux and two popular commercial fluxes were given to five expert aluminium welders to use for three months, and were requested to rate the performances. The results showed that there was an agreement between the responses of the welders that the new flux performed better than the commercial versions available in Nigeria.