Product Information (Oxalic Acid Alumite)

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Oxalic Acid Anodic Oxide Coating(Oxalic Acid Alumite)
ALMITE/Alumite(Anodic Oxide Coatings for Aluminum and Aluminum Alloys)

The oxalic acid anodic oxide coating was developed based on the invention of oxalic acid anodizing
using a process of superimposed direct current on alternating current by Tsunetaro Kujirai and Sakae
Ueki of the Kujirai Laboratory at the Institute of Physical and Chemical Research (RIKEN). Researchon the oxalic acid anodic oxide coating aimed at practical application of the coating was later takenover by Shoji Seto and Akira Miyata. Akira Miyata invented steam sealing treatment by taking a hintfrom his failure—he failed to rinse a set square in hot water. He then acquired a patent for steam
sealing of oxalic acid anodic oxide coating. Aluminum-made apparatus and equipment treated by thesteam sealing of oxalic acid anodic oxide coating was named alumite, whose logo mark was registeredas a trademark in 1931. After that, research and development aimed at industrial manufacture ofalumite started. The company engaged in the research and development was the Riken Alumite
Industry Co., LTD., which was founded with contribution from RIKEN and others. Until now, ourcompany has made a contribution to the popularization of aluminum-made apparatus and equipment
in Japan as a specialized alumite processing plant. Although oxalic acid anodic coating is excellent inquality with a very high corrosion resistance and durability, oxalic acid anodizing of aluminum takes
a high cost, and the processing of oxalic acid alumite is challenging. For this reason, sulfuric acidalumite, which is less expensive and more easily manufactured industrially compared with oxalic acidalumite, has become popular at present. Only a few companies in Japan now manufacture oxalic acidalumite.

Features◎Appearance: The coating provides a beautiful appearance with a light yellow or gold color for theproduct. (Materials with a high alloy content exhibit gray color after coating.) In particular, 5000 series
alloys exhibit a vivid gold color after coating.
◎Corrosion resistance: The coating provides a high corrosion resistance for the product.
◎Weather resistance: With a high fastness to light, the coating causes hardly any change in color tone.
Combined with its high corrosion resistance, the coating is safely applicable to products used in theoutdoor.
◎Pureness: The coating does not contain atoms heavier than Al. Only hydrous alumina and oxalate

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Product Information (Oxalic Acid Alumite)

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exist in the coating. Unlike other anodic coatings, oxalic acid anodic oxide coating releases neither
sulfur (S) nor phosphorus (P). In addition, the coating releases not any substances that interfere withfilm formation in semiconductor manufacturing equipment.

Standard performance and quality assurance - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ◎Coating thickness: 6μm as a standard (maximum 15 to 20μm (depending on the material))◎Meets JIS H8601:1999 (With the exception of the coating thickness test, any of the following
coating performance tests, when required, will be outsourced.)

Table 3: Coating thickness grade and coating performance (JIS H8603:1999 Anodic Oxide Coatings
for Aluminum and Aluminum Alloys)
Coating Thickness (μm)
Minimum
Local
Thickness

Average
Minimum
Thickness

AA3
AA5

2.4
4.0

3.0
5.0

AA6

4.8

6.0

AA10

8.0

10.0

AA15

12.0

15.0

AA20

16.0

20.0

AA25

20.025.0GradeCorrosion ResistanceAlkaline Corrosion
CASS
ResistanceTest
JIS H8681-1
JISH8681-2
Class AClass B
30 sec orlonger
50 sec orlonger
75 sec orlonger
100 sec
or longer
125 sec
or longer

90 sec or
longer150 sec
or longer
225 sec
or longer
300 sec
or longer
375 sec
or longer

8h
16 h
32 h
56 h
72 h

Abrasion Resistance JIS H8682
SandAbrasive
FallingAbrasive
Wheel
Abrasion
Jet Test
WearResistance
Test
Test
150 sec orlonger
30 cycles
500 sec or 24 sec oror morelonger
longer--------750 sec or 36 sec or
Coatinglonger
longerwear
1000 sec
48 sec or(μm)
or longerlonger1250 sec
60 sec oror longer
longer

(RN9.0 or greater)
Note: The conditions shown for Class A in the table above are applicable to hot water sealing using
nickel acetate aqueous solution and others, and those for Class B are applicable to high -pressure steam
sealing. The conditions shown in the above table are applicable to corrosion-resistant wrought alloys.

Sealing・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・
Hot water sealing and steam sealing are pore-sealing treatments utilizing hydration reactions of anodic
oxide coating. With the hydration reactions, microscopic pores of anodic oxide coating are sealed off,
while the coating becomes chemically inactivated. The sealing treatment improves corrosion
resistance and stain resistance, which is also applied to dye fixing of dyed products. In nickel acetate
sealing, orifices of microscopic pores are filled with deposits, thus preventing dye bleeding andproviding excellent corrosion resistance and surface smoothness. The high-pressure steam sealingdeveloped at RIKEN allows maximum-level hydration sealing treatment and provides outstanding
corrosion resistance. At the Riken Alumite Industry, we offer nickel acetate sealing treatment,

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Product Information (Oxalic Acid Alumite)3 / 3deionized water (hot water) sealing treatment, and high-pressure steam sealing treatment.

Table 4: Coating thickness grade and major applications (JIS H8601:1999)
Coating Thickness

Major Application

Grade
AA3
AA5, AA6, AA10

Reflectors, electrical parts (internal parts), etc.
Kitchen utensils, household products, home appliance parts, decorativeproducts, furniture components, vehicle interiors, building components(indoors)

AA15, AA20
AA25

Kitchen utensils, vehicle exteriors, civil engineering and architectural
materials, ship parts

Riken Alumite Industry Co., LTD.