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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.