Surface Finishes

Chromate Conversion Coating (Alodine) Services

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Chromate Conversion Coating (Alodine)

Chromate conversion covering, even more typically known as chem film or by its trademark name Alodine, is a chemical coating that passivates and secures lightweight aluminum from rust. It is additionally utilized as a base layer before priming and painting parts. This safety layer is much thinner than an anodizing layer, and while both are created by immersion of components into a bathroom, Alodine is a straightforward chemical layer and the procedure does not make use of electricity existing.

Alodine is a somewhat much less expensive procedure than anodizing, though it is extra prone to scrapes, wear, and aesthetic damages. Among the most usual shades of the layer is a rainbow-like greenish-gold, and therefore it might furthermore be made use of for aesthetic objectives. Nevertheless, this color originates from hexavalent chromium, which is toxic, so for RoHS compliance needs, there are clear variations of the layer offered as well.

Surface preparationColorsApplicable materialsCosmetic availabilityVisual appearance
As machined (Ra 1.6μm)Clear/ slight yellow tintAluminum (7xxx series not recommended)NoMachining marks are visible
BeadblastedClear/ slight yellow tintAluminum (7xxx series not recommended)Cosmetic on requestMachining marks are completely removed on “cosmetic” parts but may be visible on “non-cosmetic” parts

Chromate Conversion Coating (Alodine) Parts

Chromate Conversion Coating (Alodine) Process

Chromate conversion coating entails including chromic acid to steel in a chemical process that results in a slim, protective external layer. This improves a metal’s sturdiness and makes it extra resistant to deterioration.

Below’s how we apply the chromate conversion layer:

1 Parts are cleaned and degreased to remove any type of pollutant
2 Components are rinsed to get rid of any type of deposit of detergent
3 Aluminum parts are submersed in a container having the chemical option
4 Components are eliminated when a film of the wanted thickness layers the surface area
5 Components are after that rinsed again
5 Parts are then rinsed again

Chromate Conversion Coating (Alodine) Design Considerations


Chromate conversion coatings come in two primary types: hexavalent chromate and trivalent chromate. Hexavalent chromate, while effective, poses environmental and health concerns due to the presence of hexavalent chromium. Trivalent chromate, a more environmentally friendly alternative, is gaining popularity.

Hexavalent chromate coatings typically produce a gold or iridescent yellow color. Trivalent chromate coatings can vary in color, including clear, iridescent, and olive drab. Some versions are specifically designed to be clear or provide a colorless finish.

Chromate conversion coating and Alodine are related processes, but they are not exactly the same. Alodine is a brand name for a specific type of chromate conversion coating. The term “Alodine” is often used colloquially to refer to chromate conversion coatings in general, but it’s important to note that there are various types and brands of chromate conversion coatings, with Alodine being one of them.

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