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Alcoa Nomenclature System

Originated by Alcoa

Note: This list of nomenclature originated by Alcoa does not include all anodic finishes in the system. Only the designations for the most commonly used Alumilite (clear anodized) finishes are included. The nomenclature for Mechanical Finishes and Chemical Finishes are complete as listed. Only the designators for hardcoat finishes are included for cast products. The Alcoa integral color (Duranodic) system is not shown because this system is no longer in widespread use.

An example of nomenclature originated by Alcoa for an architectural clear anodized building mullion is:

Alumilite 215R1

R1 Caustic etch (sodium hydroxide), followed by
215 60-minute anodize to produce 0.7-mil minimum coating

Note that the other steps in the process, such as cleaning, deoxidizing and amount of etch are not specifically called out. This is generally left up to the finisher.

Mechanical and Chemical Pretreatments

Mechanical Finishes

A1 Preliminary grinding and polishing prior to buffing

A2 Buff directly on as-fabricated (mill finish) surface
B Polish finish (round tube only)
C1 Polish finish, No. 180-220 emery
C2 Satin finish, hand rubbed with steel wool
C3 Satin finish, compound or brushed backed sander
D Polish finish, No. 140-180 emery
E Polish finish, No. 120-140 emery
G1 Very fine sand blast
G2 Fine blast
G3 Medium blast
G4 Coarse blast
H1 Fine shot blast
H2 Medium shot blast
H3 Coarse shot blast
K Wire brush finish
M Burnished finish
N Sand burnished finish

Note: Although viable, the above nomenclature is rarely used today. It is presented here for completeness and historical value.

Chemical Finishes

R1 Caustic etch
R2 Caustic etch for diffuse reflectors
R3 Sulfuric-chromic acid etch
R4 Bright dip (nitric-hydrofluoric)
R5 Bright dip (nitric-phosphoric)

Anodic Finishes (Note: The Alcoa system designates processing conditions but does not designate coating thickness. The processing conditions are 15-percent sulfuric acid electrolyte, 12 amps per square foot, 68°F to 74°F, sealed in hot water at 208°F to 212°F for 15 minutes unless otherwise stated. Recommended anodizing times under these processing conditions, as well as nominal coating thicknesses, are given below for each finish. Anodized finishes nomenclature for castings is given only for hardcoat. The casting alloys designation for all sulfuric acid finishes is the 700 Series instead of the 200 Series used for wrought alloys. Only the most commonly used finishes are shown.)

Alcoa Alumilite System

 Coating  AnodizingTime   Coating Thickness

 (minutes)  (mils)_____
 Alumilite 200

 10  0.1
 Alumilite 201

 15  0.15 to 0.20
 Alumilite 202

 20  0.20 to 0.25
 Alumilite 204

 30  0.35 to 0.40
 Alumilite 215

 60  0.7 minimum
 Alumilite 225*

 20  1
 Alumilite 226*

 40  2

*Alumilite 225 and 226 finishes are produced at 36 amps per square foot in an electrolyte of 12-percent sulfuric acid and one-percent oxalic acid at a temperature of 50°F. These finishes are not sealed unless they are dyed.

If the above finishes are produced on castings the designation numbers start with 7 instead of 2. A hardcoat finish of 1.0 mil thickness would be designated as Alumilite 725.