Abstract: The results showed that liquid feeding is the dominant mechanism in pure aluminum castings. The porosity ratios and the coefficient of utilization of the length of the casting have varied. However, the best conditions that achieved a balance between the porosity and the coefficient of utilization of the length of the casting were the casting in a metal mold heated to a temperature of 400°C with the average porosity being 4.2%, while the coefficient of utilization of the cast is (98%). Gas porosity has also, been found to be dominant in pure aluminum castings, regularly distributed between the crystals and their boundaries and tend to be of a spherical shape.