Clear anodizing

OX-A is a clear aluminium anodizing treatment in compliance with MIL-A-8625 Type II, and ISO 7599.

OX-A anodizing treatment is composed of an electrolytic aluminium oxidation process. It is performed by dipping the substrate in a sulphuric acid solution at 20°C and by applying direct electric current.

During the process, the surface of the aluminium part is transformed, creating a protective film of aluminium oxide with a typical thickness of 10-20µm.

The OX-A treatment protects treated parts against corrosion and wear. The corrosion resistance of parts anodized with OX-A passes 336 hours in salt spray in compliance with MIL-A-8625.

The treatment is used to protect automatic machinery components, in the medical field, home appliances, and industrial components.

Aluminium die cast valve bodies anodized with OX-A


The OX-A film protects the base material from corrosion, exceeding 336 hours of salt spray exposure in compliance with the requirements of MIL-A-8625.


The layer of aluminium oxide formed by the OX-A treatment makes it possible to achieve high scratch resistance and resistance to minor wear phenomena.


Compared to other aluminium anodizing treatments, OX-A is more economical thanks to the high efficiency process.


The OX-A treatment can be pigmented to create a deep black colour, thus allowing all aluminium alloys to be given the same appearance.


Composition and applicable standards

The OX-A treatment transforms the aluminium substrate into a compact layer of aluminium oxide. The coating composition is thus strongly dependent on the starting alloy.
20÷40%50÷70%3÷5%Depending on the alloy
Technical standards
ISO 7599
MIL-A-8625 | Type II
RoHS compliance
RoHS compliant. No restricted substances present in amounts greater than the maximum tolerated concentrations.
REACH compliance
REACH compliant. No SVHCs present in amounts higher than 0.1% by weight.

Anodizable alloys

Wrought alloysCharacteristics
Containing high percentages of copper or zincCorrosion resistance★★★☆☆
Maximum thickness★★★★☆
Other alloysCorrosion resistance★★★★★
Maximum thickness★★★★★
Casting alloysCharacteristics
Alloys with Si>8% or Cu>2%Corrosion resistance★☆☆☆☆
Maximum thickness★☆☆☆☆
Die castings with Si<8% or Cu< 2%Corrosion resistance★★☆☆☆
Maximum thickness★☆☆☆☆
Other alloysCorrosion resistance★★★☆☆
Maximum thickness★★★☆☆

Treatment thickness and aesthetic appearance

Coating thickness
Standard thicknessTolerance
30% of the treatment thickness is due to external film growth and 70% is due to film growth in the surface of the aluminium part. The radial dimensional increase can thus be calculated as 30% of the treatment thickness.
Adjustment of dimensional values following clear anodizing
Uniform thickness over the entire external surface. Reduced thickness in holes.
Aesthetic appearance
Semi-polished appearance with light grey colour. The colour depends on the base alloy. Reproduces the morphology of the machined part.
Option of black colouration in the OX-AN version

Tribological properties

Wear resistance
Resistance to moderate wear and scratches.
To meet higher demands, OX-HS and OX-W treatments can deliver very high wear resistance.

Chemical properties

Corrosion resistance
The OX-A treatment makes it possible to achieve high corrosion and oxidation resistance. Exceeds requirements for resistance to the accelerated salt spray corrosion test in compliance with MIL-A-8625F Type II.
Corrosion resistance valueSubstrate material
NSS to MIL-A-8625F
≥336 hours6000 alloy
Chemical resistance
Chemical compatibility values. The actual environmental resistance must anyway be tested in the field.
Hydrocarbons (e.g. petrol, diesel, mineral oil, toluene)
Alcohol, ketones (e.g. ethanol, methanol, acetone)
Neutral saline solutions (e.g. sodium chloride, magnesium chloride, seawater)
Dilute reducing acids (e.g. citric acid, oxalic acid)
Acid oxidizing agents (e.g. nitric acid)
Concentrated acids (e.g. sulphuric acid, hydrochloric acid)
Dilute bases (e.g. dilute sodium hydroxide)
Base oxidizing agents (e.g. sodium hypochlorite)
Concentrated bases (e.g. concentrated sodium hydroxide)