Chem film or Alodine is a chemical conversion coating that’s mostly used to protect aluminum from corrosion. It’s primarily used to passivate aluminum as it protects this metal and serves as a base for paint coatings. It leaves aluminum unaffected, so it’s easier to put paint over it without changing anything.
Besides the protection against corrosion it can offer, as well as making a base for later painting, chem film also protects aluminum against the loss of electrical conductivity.
Additionally, the coating can also improve the adhesion of both paint and primer by a significant amount, as long as you apply it to the surface of the aluminum before the primer.
Chem film goes by several different names and designations:
Class 1A or 3 (non RoHS compliant)
Class 1A or 3 (RoHS compliant)
Capabilities up to 44″L x 33″W x 27″T