Chem-Film, sometimes called Alodine or Iridite, is a chemical conversion coating that is used to essentially passivate aluminum. It protects aluminum from corrosion and serves as a base for organic (paint) coatings while leaving the part dimensions unchanged. Chem-Film is applied by dipping, spraying or brushing. It is sometimes applied alongside Type II Anodizing and can be used to repair minor damage to anodized surfaces. The resultant coating is dependent on the aluminum condition. Chem-Film is generally not intended for decorative use, and has very little abrasion resistance.
The MIL-DTL-5541 specification covers chemical conversion coatings that form protective coatings by chemical reaction with aluminum and aluminum alloy; these coatings are categorized by the following types and classes.
Dow 7 is a good choice for both new and overhauled parts that have dissimilar materials such as inserts, or where conditions will tolerate a less robust and less costly alternative to Dow 17 anodizing. It makes an excellent paint base and provides the best corrosion protection of the available chemical coatings for magnesium. Dow 7 is a chemical conversion coating which results in no appreciable dimensional change to the component. The surface of components coated with Dow 7 is changed to a brassy or dark brown finish depending on the alloy. The SAE AMS-M-3171, Type III (formally Mil-M-3171, Type III) covers the Dow 7 process.
To learn more about our Chem-Film (chemical conversion) & Dow 7 services contact sales at (602) 288‐6190 or visit our operation located at: 1101 W Hilton Ave Phoenix, AZ 85007