Aluminium has a natural protective oxide surface film and affinity for oxygen, in order to improve the appearance of an aluminium part or component through conversion coating, painting, anodizing or plating processes, requires some additional surface treatment processing to remove the natural oxide layer.

Once aluminium and alloys are exposed to etching solutions, the oxides are often removed but then depending on the alloy of aluminium, there are surface adherent non-reactive reaction products referred to as “smuts” on their surfaces. Desmut formulations are required to remove these from the surfaces of aluminium parts or components. The types of smuts present are related to the alloy of aluminium. For example, 200 series wrought aluminium have resulting copper smuts that are effectively removed by iron based desmut formulations. Alloys containing silicon or magnesium smuts are thoroughly desmutted with blends of acids including fluorides, nitrates & sulphates. All surface smuts must be removed for success with applications of conversion coatings, painting, anodizing or plating aluminium and alloys. Choices for Anodizing applications include ALUMAL DEOX 411, 436 or 444. For chemical conversion coating prior to painting, review ALUMAL DEOX 411, 425, 445, or 427.