Difference between mill finish aluminum & chromatized finish

What is the difference between mill finish & chromatized finish in aluminium? kindly explain if anybody knows.

Hi, Thiru.

To the best of my knowledge, "mill finish", means the natural finish that is achieved by the mill when they roll, cast, or extrude a product. In other words, no effort has been made toward improving the finish. "Chromatized" is slang rather than a specification, and as such, there is always the possibility that one person meant something a bit different than the other guy, but I would interpret it to mean that the aluminum was chromate conversion coated; one example of a specification for chromate conversion coating of aluminum is Mil-DTL-5541. This would generally imply that a multi-step process has been performed on the aluminum that cleans and desmuts it prior to the application of a chromate conversion coating that renders it uniform in appearance, reasonably corrosion resistant, and with a base layer suitable for adhesion of paint.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey