Anodic Coating Designation System
Matching processing & required anodic film thicknesses with customer needs
The chemical finishes and comparative anodic coatings charts are designed as guidelines that match processing and required anodic film thicknesses with customer needs.
Chemical Finishes
| Type of Finish | Continuous Coil Anodizers Assn. | ALCOA Designation | Alum. Assn. Designation | Description | Examples of Methods of Finishing (Not Definitive Techniques) |
|---|---|---|---|---|---|
| Non Etched Cleaned | N.P.T. (No Pretreatment) | — | C-10 | Unspecified | — |
| — | — | — | C-11 | Degreased | Organic solvent treated |
| — | — | — | C-12 | Inhibited Chemical Cleaned | Inhibited chemical type cleaner used |
| — | — | — | C-1x | Other | To be specified |
| Etched | Matte, Satin | R1, R2, R3 | C-20, C-21 | Unspecified, Fine Matte | Trisodium phosphate, 3–6 oz./gal. used at 140–160°F for 3–5 min. |
| C-22 | Medium Matte | Sodium hydroxide, 4–6 oz./gal. used at 140°F for 5 min. | |||
| C-23 | Coarse Matte | Sodium fluoride, 1½ oz. plus sodium hydroxide 4–6 oz./gal. used at 140°F for 5 min. | |||
| C-2x | Other | To be specified | |||
| Brightened | Chem. Brighten / Bright-dipped (R5) | R5-Bright Dip*, EB10, EB30, R1–R5 Bright Dip | C-30, C-31 | Unspecified, Highly Specular | Chemical bright dip solution of the proprietary phosphoric-nitric acid type used, or proprietary electro-brightening |
| C-32 | Diffuse Bright | Etched finish C-22 followed by brightened finish C-31 | |||
| C-3x | Other | To be specified |
Comparative Anodic Coating Designation
| Film Thickness | Continuous Coil Anodizers Assn. Designation | ALCOA Designation | Aluminum Assn. Designation | Description | Type of Finish |
|---|---|---|---|---|---|
| .0001–.0007+ — Nonstandard flash (<.001 film thickness); Interior commercial standard .0001 to .0002 film thickness | — | Alumilite 200 (.0015 minimum thickness) | A21, A22, A23, A2X | Clear (natural) coating; Coating with integral color; Other | Protective & Decorative (coatings less than 0.4 mils thick; thickness to be specified by customer) |
| Architectural Class II: .0004 to .0007 | Architectural Class II .0004 to .0007; Architectural Class I .0007 and up | Alumilite 204 (.0004 minimum thickness) | A31, A32, A33, A3X | Same as above | Architectural Class II (0.4 to 0.7 mil coating) |
| Architectural Class I: .0007 and up | Alumilite 214 (.0006 minimum film thickness) | A41, A42, A43, A4X | Same as above | Architectural Class I (0.7 mil and greater anodic coating) |
Ordering Specifications
Covering Area (Yield) and Weight per Square Foot
Aluminum Sheet and Foil Gauges
| Decimal Thickness | Pounds Per Square Foot | Square Feet Per Pound | Decimal Thickness | Pounds Per Square Foot | Square Feet Per Pound |
|---|---|---|---|---|---|
| .002 | .028 | 35.6 | .025 | .352 | 2.85 |
| .003 | .042 | 23.75 | .026 | .364 | 2.74 |
| .004 | .056 | 17.8 | .027 | .379 | 2.64 |
| .005 | .070 | 14.25 | .028 | .392 | 2.55 |
| .006 | .084 | 11.9 | .030 | .422 | 2.38 |
| .007 | .099 | 10.1 | .031 | .435 | 2.30 |
| .008 | .112 | 8.9 | .032 | .450 | 2.23 |
| .009 | .127 | 7.9 | .034 | .478 | 2.09 |
| .010 | .141 | 7.1 | .036 | .505 | 1.98 |
| .011 | .154 | 6.5 | .038 | .533 | 1.88 |
| .012 | .169 | 5.95 | .040 | .563 | 1.78 |
| .013 | .184 | 5.43 | .042 | .590 | 1.69 |
| .014 | .197 | 5.1 | .044 | .617 | 1.62 |
| .015 | .210 | 4.77 | .045 | .631 | 1.59 |
| .016 | .224 | 4.45 | .046 | .645 | 1.55 |
| .018 | .253 | 3.95 | .047 | .660 | 1.52 |
| .019 | .268 | 3.74 | .048 | .674 | 1.48 |
| .020 | .282 | 3.55 | .050 | .704 | 1.42 |
| .022 | .309 | 3.24 | .051 | .719 | 1.39 |
| .023 | .322 | 3.11 | .056 | .785 | 1.27 |
| .024 | .339 | 2.95 | .063 | .889 | 1.125 |
| Based on a density of .0976 pounds per cubic inch (Specific Gravity of 2.70) | |||||
Alloys suitable for anodizing
| Alloy | Product Form | Characteristics |
|---|---|---|
| 99.99 | Pure Al in sheet, plate or extrusion | Gives highest reflectivity since oxidized surface is free of Si, Fe and Mn which normally obscure polished surface. Easily formable, but low in strength, and expensive. Used primarily for simulated gold finish. Super-purity Al-Mg and Al-Mg-Si alloys give the same brightness; cost is still high, but strength is much improved because of Mg additions. |
| 5005, 5252, 5257, 5357, 5457, 5557, 5657 | Al-Mg alloy in sheet form | Reflectivity is below that of high-purity Al-Mg alloys, but they respond well to anodizing, have good mechanical properties, and are priced for commercial applications like automotive, appliance, and architectural trim. Alloying constituents do not tint coatings. |
| 6063 | Extrusion alloys | These heat-treatable alloys combine high strength and good response to anodizing. Contain Mg and Si as MgSi. Heat treatment dissolves silicide, improving strength and luster after anodizing. Presence of Si can give coating a gray or brown tint. |
| 1100 | Sheet and plate | Alloy 1100 is commercially pure Al, but has some Si and Fe which diminish reflectivity under anodized coating. Presence of Si can give coating a gray or brown tint. |
| 3003 | Al-Mn alloy in sheet or plate | This commercial alloy has excellent formability and, though widely used for anodic finishing, has less reflectivity than 1100 or 5005 after anodizing because of Mn and lower Al purity. Since MnO is brown, thick anodized films on this alloy have a brownish tint. |
| 5052 | Al-Mg alloy in sheet or plate | Structural alloy containing Cr as well as Mg, widely used for welded parts. Presence of Cr gives thicker anodic coatings a yellowish tint. |
| 6061, 2014, 2024, 7075 | Extrusion, sheet and plate | Heat-treatable, these alloys rank after 5052 in reflectivity because Al purity is lower. Cr in 6061 and 7075 gives thicker anodic coatings a yellowish tint. |
| Reprinted from Product Engineering | ||
