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

Brightened

Chem. Brighten Bright-dipped (R5)

R5-Bright Dip*
EB10, EB30
R1-R5
Bright Dip

Film Thickness

Contiunous Coil Anodizers Assn. Designations

ALCOA Designations

Aluminum Assn. Designations

Description

Type of Finish

.0001

.0002

.0003

.0004

.0005

.0006

.0007

up

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

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 cubic inch (Specific Gravity of 2.70)

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