The Chromize Free Passivation for Aluminum treatment is an intermediate process, which protect the aluminum surface with a chemical reagent. It can increase the surface roughness and superficial area, then to enhance the surface protective capacity and coating adhesion, Then it will avoid or reduce the coating shedding in the subsequent processing.
The aluminum for wines closures (≥3cm) and medicine closures should have this treatment, the high strength of deep drawing and partial severe deformation will make the coating fall off, the phosphor treatment is necessary. After phosphor treatment, the aluminum may have problems when it across the coating machine. It is a normal condition. Using DOS oil after phosphor treatment to solve this problem. DOS oil can protect the aluminum surface, and it is easy to volatilize, so will not affect the final printing effect.