As long as aluminum has been manufactured and melted, various by-products with a mixture of aluminum and aluminum oxide have existed. The general name for this class of materials has historically been called “dross”. Within the larger family of drosses, there are a number of subclasses which we will explore. Unfortunately, the presence of even minor amounts of oxide in aluminum metal, render it useless for most structural applications. To be of value the aluminum metal must be free of oxides. Additionally, the inherently high value of the metal has driven innovation in methods to effectively and economically separate the metallic values from this mixture. This paper will present background information on the formation of drosses and the historical methods used to process the drosses.