Mansour mastered various painting and sculpting techniques. His artworks could be divided into four phases:
- 50' to mid 60's: Experimenting with various painting techniques influenced by the tutoring of Manetti himself. Nature, Still Life paintings, and portraits were the dominant subjects of his artworks during this period. It is clear from his paintings that he was experimenting with various techniques mainly oil.
- Mid 60's to Mid 70's: During his stay in Europe, mainly in the UK, Mansour mastered oil painting. Most of his works influenced by 19th and 20th century British artists, focusing mainly on Genre-Painting, Portrait and Still life. During this period he also mastered various sculpting techniques, and worked many sculptures for the Madame Tussaud museum.
- 1977 - 1990's: During this period, the Lebanese war erupted. Mansour was greatly influenced and touched by the atrocities of the war. His works during this period mirrored violent events and its influence on people. This is clearly showing in his paintings where the intense emotions were reflected on the faces of his subjects as well as the overall scenery of war and destruction. During this phase there was a tendency to shift from oil to pastel and charcoal as well as water colors in his paintings. This was mainly due to the fact that oil paintings would take a substantially longer time to finish during a period of instability and continuous move to shelters avoiding heavy shelling. In addition to that he was forced to use whatever material and painting utensils available for him at that time. His sculptures also reflected dramatic events. It also embodied his longing towards an equal, free and prosperous society.
- Late 90's - 2010: Following the end of the Lebanese war, Mansour was morally and psychologically devastated by the long years of the civil war and the various foreign occupations of his country. He was in a state of despair and depression as his utopian vision of a just and equal society after a fierce civil war was shattered into pieces. At this stage and as if trying to erase the war's impact on him, he worked solely with Pastel, crayons and water colors. Famous for his pastel techniques, he used ultra bright colors in his paintings in a very homogeneous non repulsive manner seamlessly blending them together, focusing mainly on nature and people working their land.