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 Designations

Alum. Assn. Designations

Description

Examples of Methods of Finishing
(Not Definitive Techniques)

Non Etched Cleaned

N.P.T. (No Pretreatment)

C-10
C-11
C-12

C-1x

Unspecified
Degreased
Inhibited
Chemical
Cleaned
Other

Organic solvent treated
Inhibited chemical type
Cleaner used.
To be specified.

Etched

Matte
Satin

R1
R2
R3

C-20 C-21	Unspecified Fine Matte	Trisodium phosphate, 3-6 oz./gal. used at 140-160oF for 3-5 min.
C-22	Medium Matte	Sodium hydroxide, 4-6 oz./gal. used at 140oF for 5 min.
C-23	Course Matte	Sodium fluoride, 1 1/2 oz. plus sodium hydroxide 4-6 oz./gal. used at 140oF 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 propietary electro-brightening
C-32	Diffuse bright	Etched finish C22 followed by brightened finish C31
C-3x	Other	To be specified

Comparative Anodic Coating Designation

Film Thickness

Contiunous Coil Anodizers Assn. Designations

ALCOA Designations

Aluminum Assn. Designations

Description

Type of Finish

.0001

.0002

.0003

.0004

.0005

.0006

.0007

up

Nonstandard flash (less than .001 film thickness)

Interior commercial standard .0001 to .0002 film thickness

Alumilite 200 .0015 minimum thickness

A 21

A 22

A 23

A 2X

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 I .0007 and up

Alumilite 204 .0004 minimum thickness

A 31

A 32

A 33

A 3X

Same as Above

Architectural Class II (0.4 to 0.7 mil coating)

Alumilite 214 .0006 minimum film thickness

A 41
A 42
A 43
A 4X

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	.012	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 cubicinch (Specific Gravity of 2.70)

Alloys suitable for anodizing

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. Alloy 5005 has some Mg for moderate strengthening.
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. Alloy 5005 has some for moderate strengthening.
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