Chem film, also called chemical film, is a chemical conversion coating. It typically refers to a chromate conversion coating applied to aluminum and its alloys. The chemfilm coating provides a layer of corrosion protection and a base for paint and primer. When applied as a thin coat, chem film can allow for electrical conductivity.
Chem film coatings are marketed under brand names such as Alodine®, Iridite® and Chromicoat®.
The chemfilm coating process is often governed by the commonly used MIL-DTL-5541 standard, which specifies different types and classes of chem film coatings.