What is a blue anodized aluminum sheet


Electrolytic OXidation of aluminum

Anodizing / anodizing transforms the surface of aluminum into a dense, very hard oxide layer that is inextricably linked to the base material. Anodized surfaces do not corrode, protect against mechanical impact and are insensitive to the effects of the weather. Because oxide layers are transparent, the gloss and metallic look are retained.

The structure of the aluminum surface can be chemically or mechanically pretreated (E0-E6). The changes in the reflective properties resulting from grinding, brushing, polishing or pickling have a major impact on the appearance of the material. Pretreatment and dyeing processes can be combined and open up numerous options for product design, while at the same time preserving the metallic appearance.

Information on anodizing processes

Color & structure

The transparent anodized layer optically corresponds to the natural color of aluminum (color EV 1). There are two ways to change the look of the material:

  1. With colored coloring in two-step color and SANDALOR® Process, or in gray with the GRANODAL® Procedure.

  2. By chemical or mechanical pretreatment such as pickling or grinding. This changes the reflective properties of the anodized surface.
    Both options can be combined to create a wide variety of design options, all of which retain the metallic appearance.

Information about anodizing and color

SANDALOR® Color anoxal

The SANDALOR® - Process offers additional coloring options. For outdoor use, metal construction and architecture, we anodize and color in the lightfast colors yellow, gold, red, blue and turquoise; for indoor use, orange and green are also available. SANDALOR® Colors are available in 5 different levels of brightness and through pretreatment such as grinding or polishing, the surface structure and thus the appearance can be changed. The SANDALOR® Information page provides detailed information.


Aluminum with a stainless steel look. ALANOX®, is a surface from ALUTECTA that makes aluminum look like stainless steel. The stainless steel effect is produced by combining a special multiple grind and one for ALANOX® developed coloring. The anodized surface is lightfast, resistant to fingerprints and can be produced for profiles and sheets up to a width of 400mm. The ALANOX® The product page describes technical information, advantages and possibilities of aluminum with a stainless steel look.


With GRANODAL®, the coloring process developed by ALUTECTA, anodized aluminum sheets and profiles are colored gray with inorganic dyes. This makes the surfaces lightfast and enables the use of gray anodized surfaces in architecture. GRANODAL® is available in 3 brightness levels and a stainless steel look. On the GRANODAL® Product page you will find examples and detailed information.

Engraving plates

Engraving plates / anodized sheets in engraving quality. Alutecta has been a strong partner to the engraving industry for years. The production of engraving plates takes place in-house according to special quality standards. After anodizing, all sheets are wrapped in foil and packed ready for transport. A large selection of colors and sheet thicknesses are stored with us and can be delivered immediately.
Info page engraving plates

The terms anodizing and anodizing denote a process of surface technology in which aluminum parts are used as anodes in an electrolyte to convert the surface into an oxide layer. Anodization is the international name, ELOXAL is the name in German-speaking countries and stands for Tbspectrolytic OXidation of ALuminium.

Anodic oxidation or anodizing / anodizing transforms the aluminum surface into a dense and very hard protective layer that is firmly bonded to the base material. It offers protection against mechanical influences and is weather and corrosion resistant. The metallic luster of the material is retained because the oxide layer is transparent. The oxide layer created in an electrolyte under the influence of direct current can be colored using various methods. The dye is stored in the layer and remains protected from harmful environmental influences. The technical information on anodising offer detailed information on density, hardness, abrasion resistance and specific electrical resistance.

Anodized aluminum can easily be recovered for reprocessing and thus represents an environmentally friendly type of surface refinement that meets the requirement of sustainability.

Possible dimensions of the components depending on the geometry up to:
Length 7000 mm x width 800 mm x height 2000 mm

The anodized layer produced by anodizing is transparent. The material retains the natural color of aluminum. There are two ways to change the look of the material:

1. Anodized layers can be colored in various processes.
Here you will find an overview of the color options




Color /






2. The aluminum surface can be pretreated chemically or mechanically. This changes the structure and the reflective properties of the surface.

Both options can be combined to create a wide variety of design options, all of which retain their metallic appearance.

The following illustrations show the combination of color e.g. S100-0 and the various pre-treatments E0-E6 and the changed visual effect.

E1 S100-0

Surface with a clearly visible cut.

E2 S100-0

Very fine drawing / brush strokes

E5 S100-0

High gloss reflective surface

E6 S100-0

Uniform matt surface with a soft feel

Pretreatment E0-E6 according to DIN 17611

Anodically generated oxide layers are transparent. Most of the light falling on an anodized surface is not reflected on the surface of the oxide layer, but on the interface with the metal. Therefore, the metallic appearance is retained during anodizing.

The type of pretreatment is therefore of decisive importance for the visual effect of anodized aluminum.

A distinction is made between chemical pretreatment by pickling in an alkaline solution, which creates a matt surface, and mechanical pretreatment, e.g. by brushing, grinding or polishing. Different surface effects can be achieved in this way (gloss, grinding or matting).

The type of pretreatment is identified by the corresponding abbreviations E0 to E6 according to DIN 17611.


Without pre-treatment
Draw marks, scratches, chafe marks and other surface defects remain visible. Suitable for subordinate surfaces that are not in the field of vision, e.g. backing up shadow gaps, for push rods, etc.


Relatively even, somewhat dull-looking surface: Small drawing marks and scratches are removed (no flat grinding). Depending on the abrasive grain, coarse to fine grinding marks are visible.


Even, light surface: the brush strokes are visible. Draw marks, scratches, etc. are only partially removed. Easy to care for, increased self-cleaning effect outdoors. Usually used as a mechanical pretreatment.


Shiny surface: Draw marks, scratches, etc. are only partially removed. Use preferably indoors. Easy care.


Sanded and brushed
Even, bright surface: grooves, scratches, chafing, etc., - especially hidden signs of corrosion, - which can be seen with E0 or E6, are removed (no flat grinding). Easy care.


Honed and polished
Smooth, shiny surface: grooves, scratches, chafing, etc., - especially hidden signs of corrosion, - which can be seen at E0 or E6, are removed (no flat grinding).


Chemically pretreated
Matt, rough surface: grooves, scratches, etc. are partially leveled out. Material-related changes in the surface appearance cannot always be avoided. Any signs of corrosion affecting the decorative appearance, which are not or only with difficulty noticeable before the pickling, can become visible through this treatment.

Anodizing - the process

In a naturally occurring process, aluminum forms an oxide skin that usually protects the material from further attack. This process is optimized under technical conditions in the anodizing bath. Aluminum is therefore the only material that can be anodized. The natural oxide skin of an aluminum component is only 0.1-0.5 µm thick, undecorative and not very hard. The technically produced anodized layer, on the other hand, has precisely specified properties in terms of layer thickness, structure, hardness and optical homogeneity.

The anodized layer is created in an electrolyte, e.g. sulfuric acid. In the electrolyte bath, the material to be anodized is connected as an anode and a direct current is applied. The cathodes are located on the edge of the bath. The desired anodized aluminum layer is created in a very complex electrochemical reaction2O3. At first a rather thin but closed barrier layer forms. If the layer continues to grow, capillary-like pores are created (see graphic).

Graphic: Aluminum surface with empty anodized pore:

The energy released during the entire process is recovered and used to heat the production halls. The parameters selected during anodizing can be used to determine properties such as hardness and pore size of the anodized layer.
The open-pored surface after the anodizing bath offers the unique possibility of storing different (gold, brown, black, blue, red, yellow, turquoise, etc.) colors in these pores. The color is not stored on the surface, but in the anodized pore and is therefore completely protected (see also color anodizing). The last step in the process is to compress the pores. Under the action of fully demineralized water at 100 ° C, aluminum oxide hydrate is produced. The transparent aluminum oxide hydrate forms in the pore and hermetically seals it so that the color is additionally protected (see graphic).

Graphic: aluminum surface with anodized pore and compression

Compaction is a crucial step for the corrosion resistance and longevity of the aluminum surface.

We will be happy to provide you with samples!

Color two-step process

The transparent anodized layer produced during anodic oxidation (anodizing) corresponds to the natural color of aluminum (EV 1). Following this colorless oxidation, the layer can be colored electrolytically in a second stage with the aid of a metal salt solution. The metal oxides embedded in the open-pored anodized layer result in light-resistant color tones, the brightness of which can be graded from light beige to bronze to black (C11 - C14). The color effect is not created on the surface of the anodized layer, but completely protected against environmental influences on the pore base of the anodized layer (see graphic - aluminum surface with anodized pore, color and compression).

Possible dimensions of the components depending on the geometry up to:
Length 7000 mm x width 800 mm x height 2000 mm

We will be happy to provide you with samples!


After the color has been stored, the pores are closed. This process is called compression or sealing (see also “The Process”). Compression is always the final step in the anodizing process and is crucial for the aluminum's resistance to weathering and corrosion.

Overview of color - color options




Color /

Stainless steel look

The Sandalor® - procedure

Through the combination of the two-step color dyeing and adsorptive immersion dyeing in the Sandalor® - Processes can produce numerous color tones (blue, red, orange, yellow, black, green, gold, etc.) in different levels of brightness. While the electrolytically deposited metal oxides can be found at the bottom of the pore, the adsorptive dyes tend to be deposited on the pore walls (see graphic). The lightfastness of the dyes we use is above 8 on the ISO blue scale. The color effect is extremely lively and metallically luminous.

Possible dimensions of the components depending on the geometry up to:
Length 7000 mm x width 600 mm x height 2000 mm

We will be happy to provide you with samples!

Sandalor® - compression

Graphics: Aluminum surface with Eloxalpore, color two-stage coloring, Sandalorf coloring and compression

In the end the Sandalor® As with all other anodizing processes, the pores are closed with the dyeing process. The compression or sealing ensures the weathering / corrosion resistance.

Overview Sandalor® - color options






Our new anodized surface ALANOX® makes aluminum look like stainless steel. A special multiple cut combined with a special coloring results in the stainless steel effect, which is particularly in high demand in architecture. But stainless steel is also being used more and more in other areas (e.g. furniture). For the metal worker, aluminum with a stainless steel effect has the advantage that he is used to processing aluminum and that there are hardly any restrictions in terms of construction. The material costs are lower than with stainless steel, there are no problems with fingerprints and by ALANOX® there are new possible uses for the material aluminum. The layer thickness is at least 20 µm.

In addition to profiles, sheet metal blanks with maximum dimensions of 7000 mm in length and 400 mm in width can also be processed.

Possible dimensions of the components depending on the geometry up to:
Profiles: length 7000 mm x width 400 mm x height 2000 mm
Sheets: length 7000 mm x width 400 mm x height 2000 mm

ALUTECTA presents GRANODAL® - Sizeouch anodized Aluminium

GRANODAL® is a process developed by ALUTECTA for coloring anodized aluminum in various shades of gray. The resulting surface is characterized by its exceptionally elegant look and feel. The metallic character is retained with this purely inorganic coloring. The result is a shimmering, very lively surface in many, rather neutral gray tones, with no tendency to blue or green tones. The coloring is UV-resistant and weatherproof, so it is not subject to any fading or any tendency to blotchiness when exposed to weathering. In addition to these properties, the well-known positive quality features of anodized aluminum are evident - scratch-resistant, long-lasting and corrosion-resistant. GRANODAL® shows its strengths also and especially in outdoor use and guarantees the durability of the refined products and design ideas in numerous industries.

Advantages and properties of GRANODAL® :

  • UV and weather resistant
  • durable, scratch-resistant and corrosion-resistant
  • no application of a layer of paint, purely inorganic surface
  • lively, metallic reflective surface
  • extraordinary and noble optics
  • for a wide range of innovative products

Possible dimensions of the components depending on the geometry up to:
Length 6500 mm x width 400 mm x height 2000 mm

GRANODAL® uses the physical properties of metal particles embedded in the anodized layer. The shape and alloy of the refined components are decisive for the resulting color effect - an effect that emphasizes the individual character of the material and contributes to the uniqueness of your design and products.

GRANODAL® is offered in three different colors from C71-C73, complemented by the stainless steel look ALANOX®Gray and varies due to the numerous possibilities of surface pretreatment such as brushing, grinding, pickling and polishing.

Please contact our sales department by phone for further explanations and status on this topic.

Alutecta has been a strong partner to the engraving industry for years. The production of engraving plates takes place in-house according to special quality standards. After the surface refinement, all sheets are wrapped in foil and packed ready for transport. The following colors are stored with us and can be delivered immediately.
Nature EV1
German silver G1A
Gold EV3
Stainless steel look (ALANOX-G1, only matt, only on one side)
Light bronze C11, medium bronze C12, dark bronze C13
Black C65-1
Green S170-0, red S140-0, blue S150-0

Anodizing in engraving quality offers:

  • High-quality anodized surface in different colors on aluminum sheets suitable for engraving
  • Various sheet thicknesses available directly from stock
  • Finishes in gloss and matt possible
  • Visible sides one-sided / two-sided, (including protective film one-sided / two-sided)
  • Dimensions = 1000x2000mm / 500x1000mm
  • Sheet thicknesses gloss = 1.0mm, 1.5mm, 2.0mm
  • Sheet thicknesses matt = 0.5mm, 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, 4.0mm
  • Sheet thickness stainless steel look = 1.0mm, 1.5mm, 2.0mm
  • Protective film 75my
  • Material = AlMg3 GQ + EQ (matt) / AlMg1 AG1S (gloss)

Minimum quantities

  • per color in 1000 * 2000mm = 12 pieces on one side / 6 pieces on both sides
  • per color in 500 * 1000mm = 48 pieces on one side / 24 pieces on both sides


Untreated aluminum forms a natural oxide skin under the influence of the atmosphere, which usually protects the base material from further corrosion. However, this oxide skin is very thin (0.1-0.5 µm after a few months), not decorative and is not very hard. The natural process can be used in a technically optimized way to produce a much thicker and harder anodized layer that is highly decorative and can be colored.

Anodized aluminum components combine many advantages. Good processability and high strength of the material allow almost free design. The anodized surface stands for protection and low maintenance. The structure and color range gives you a lot of leeway for the design of the surface and the optical effect of your aluminum idea.

The resulting anodized layer is electrically non-conductive, very hard and can be colored (see color anodized). Thanks to a special printing process, it is also possible to incorporate color into the anodized layer in such a way that the print is absolutely resistant to abrasion. The anodized layer made of Al2O3 is ceramic, very thin and firmly bonded to the aluminum. When an aluminum component is recycled, the oxide layer remains in the furnace and can be easily removed.

technical advice

We would like to provide you with the following information as a guide, the numerical values ​​are taken from the literature. Please understand that we cannot accept any liability for the correctness of the information.


Aluminum oxide (anodized)3.94 kg / dm3
 for comparison
aluminum2.7 kg / dm3
steel7.85 kg / dm3
Stainless steel 1.43017.95 kg / dm3

Hardness in HV (Vickers)

Anodized layer250 - 450 HV (Vickers)
 for comparison
aluminum50 - 70 HV
Quenched and tempered steel150 - 320 HV
Stainless steel 1.4301150 - 200 HV
Without information, layer thicknesswe anodize approx. 20 µm (0.02 mm)

Abrasion resistance (wear resistance)

AlMg 1 (EN AW 5005)3000 - 5000 revs. at 1000 g according to Taber
AlMgSi 0.5 (EN AW 6060)9000 - 12000 strokes / µm according to Siemens + Halske

Breakdown voltage

Anodized layer30 V / µm results in approx. 600 V at 20 µm

Thermal conductivity

AlMg 1 (EN AW 5005)160 - 220 W / (m K)
 for comparison
AlMgSi 0.5 (EN AW 6060)200 - 220 W / (m K)
Aluminum oxide (anodized)28 W / (m K)
Stainless steel 1.430115 W / (m K)

Expansion coefficient

Anodized layer6 x 10-6/ K
 for comparison
aluminum23 x 10-6/ K
steel11 x 10-6/ K
Stainless steel 1.430116 x 10-6/ K

Specific electrical resistance

Aluminum oxide (anodized)1 • 1018 Ω mm2/ m
 for comparison
aluminum2,65 • 10-2 Ω mm2/ m

Dielectric constant

Anodized layer5 - 6
 for comparison
Glass5 - 7

Cleaning + care

Due to the very hard and resistant oxide layer, anodized components can be freed from stubborn dirt particularly well. It is insensitive to scratches and easy to care for.

For components that are used outdoors, an initial cleaning as an abrasive basic cleaning is essential. In the weather, aluminum components, like all other materials, are subject to natural pollution. In order to maintain the decorative appearance, an interval cleaning and maintenance adapted to the degree of soiling and the requirements for the decorative appearance of the components in accordance with the recommendations of the Gütegemeinschaft für den Metallfassaden e.V.


Small imperfections and scratches can be concealed with special anodized touch-up pens or anodized sprays, which you can obtain from us. Components with serious processing defects or extensive damage may have to be de-anodized and reworked.

UniversAL for anodising

Our UniversAL cleaner is suitable for all anodized / anodized surfaces. Properties: cleaning, preservation and care of anodized / anodized surfaces. The special product contains care components, solvents and preservatives. It also protects the anodized layer from the weather and environmental pollutants. UniversAL is free from polishing agents, silicone compounds and aromatic hydrocarbons.

UniversAL cleaning & preservation for use on anodized / anodized aluminum surfaces is available in a set with 100ml bottle and cleaning cloth or in a 500ml bottle. UniversAL is also used on powder-coated surfaces.