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Find Technical Details

Aluminum Association Designation System

for Aluminum Finishes

The Aluminum Association Designation System divides finishes for aluminum into three major categories:
  1. Techanical Finishes (M)
  2. Chemical Finishes (C)
  3. Coatings
The Coatings category is subdivided into:
  • Anodic Coatings (A)
  • Resinous and Other Organic Coatings (R)
  • Vitreous Coatings (V)
  • Electroplated and Other Metallic Coatings (E)
  • Laminated Coatings (L).
Each category and subcategory is designated by a letter. Only designations pertaining to pretreatment and anodizing are detailed in this reference. The various types of anodized finishes are designated by the letter "A" followed by a two-digit number to call out the specific anodic finish. Finishes designations may be used singly or in conjunction with other designations to specify a complete finishing system. When designations for the anodic coating are used alone, the pretreatment is usually left up to the processor to determine best fit for the product and its end use.

Example of a typical finishing designation for an interior architectural panel might be:

AA Aluminum Association Designation
M42 Fine matte, nondirectional textured mechanical finish
C21 Fine matte chemical etch
A34 Architectural Class II anodize, electrolytically colored.

Note: The finisher and customer will determine, by sampling or discussion, exactly what process constitutes the M42 and C21 finishes.

Example of a typical finishing designation for automotive trim could be:

AA - Aluminum Association
M11 - As fabricated specular
C11 - Degreased, nonetched cleaned.
C31 - Highly specular chemical brightening
A21 - Protective and decorative clear anodic coating less then 0.4 mil thick

The following lists do not contain every designation in the Aluminum Association's system. Publication 45 is updated periodically; the complete current edition is available through the Aluminum Association.


The mechanical finishes are broken down into four groups.

As Fabricated

M10 - Unspecified
M11 - Specular as fabricated
M12 - Nonspecular as fabricated
M1X - Other (to be specified)


M20 - Unspecified
M21 - Smooth specular
M22 - Specular
M2X - Other (to be specified)

Directional Textured

M30 - Unspecified
M31 - Fine satin
M32 - Medium satin
M33 - Coarse satin
M34 - Hand rubbed
M35 - Brushed
M3X - Other (to be specified)

Nondirectional Textured

M40 - Unspecified
M41 - Extra fine matte
M42 - Fine matte
M43 - Medium matte
M44 - Coarse matte
M45 - Fine shot blast
M46 - Medium shot blast
M47 - Coarse shot blast
M4X - Other (to be specified)


Nonetched Cleaned

C10 - Unspecified
C11 - Degreased
C12 - Inhibited chemical cleaned
C1X - Other (to be specified)


C20 - Unspecified
C21 - Fine matte
C22 - Medium matte
C23 - Coarse matte
C2X - Other (to be specified)


C30 - Unspecified
C31 - Highly specular
C32 - Diffuse bright
C3X - Other (to be specified)

Chemical Conversion Coatings (Note: These processes are not followed by anodizing.)

C40 - Unspecified
C41 - Acid chromate-fluoride
C42 - Acid chromate-fluoride-phosphate
C43 - Alkaline chromate
C4X - Other (to be specified)



A10 - Unspecified
A11 - Preparation for other applied coatings
A12 - Chromic acid anodic coatings
A13 - Hard, wear- and abrasion-resistant coatings
A1X - Other (to be specified)

Protective and Decorative (Coatings less than 0.4 mil thick)

A21 - Clear - Coating thickness to be specified.
A22 - Integral color - Coating thickness to be specified. Color dependent on alloy and processing conditions.
A23 - Impregnated color - Coating thickness to be specified.
A24 - Electrolytically deposited - Coating thickness to be specified.
A2X - Other (to be specified)

Architectural Class II (0.4 to 0.7 mil coating)

A31 - Clear
A32 - Integral color
A33 - Impregnated color
A34 - Electrolytically deposited color
A3X - Other (to be specified)

Architectural Class I (0.7 mil and thicker anodic coatings)

A41 - Clear
A42 - Integral color
A43 - Impregnated color
A44 - Electrolytically deposited color
A4X - Other (to be specified)