How to Specify Finishes on Aluminum

Identify & Furnish the Finish You Need

The Aluminum Association has developed a system of designation for finishes on aluminum to assure that your suppliers can identify and furnish the finish you specify.

Specific finishes of the various types are designated by a letter followed by a two-digit numeral. Each designation may be combined into a single composite designation to identify a sequence of operations covering all of the important steps leading to a final complex finish.

Almost all finishes used on aluminum may be subdivided into three major categories: mechanical finishes, chemical finishes, coatings.

Descriptions of the most commonly utilized finishes are as follows:

Mechanical: (M)

M10 - Unspecified as fabricated
M22 - Specular-buffed
M32 - Medium satin-directionally textured

Chemical (C)

C12 - Inhibited chemical cleaned
C22 - Medium matte etch
C31 - Highly specular - brite dip
C32 - Diffuse brite dip

Anodic Coatings (A)

Protective and Decorative (less than 0.4 mils thick)

A21 - Clear
A22 - Integral Color
A23 - Impregnated color (absorbed dye)

Architectural Class II (0.4-0.7 mils thick)

A31 - Clear
A32 - Integral Color
A33 - Impregnated color
A34 - Electrolytically deposited color (2-step)

Architectural Class I (0.7 mil and thicker anodic coating)

A41 - Clear
A42 - Integral Color
A43 - Impregnated color
A44 - Electrolytically deposited color (2-step)

All designations are appropriate for non-architectural applications as well.

Composite designation examples:

All composite designations are preceded by the letters AA to identify them as an Aluminum Association designation.

Example 1: Aluminum Association (plus) Mechanical Finish (plus) Chemical Cleaning (plus) Chemical Etching (plus) Anodic Coating translates to: an Architectural Class II clear matte anodized finish designated as: AA-M10 C12 C22 A31.

Example 2: An Architectural Class I textured medium bronze electrolytic deposition (2-step) would be designated: AA-M32 C12 C22 A44.

Example 3: An Architectural Class I diffused brite electrolytic deposition and overdye (3-step) would be designated: AA-M10 C12 C32 A44/43.