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Colourful anodization of aluminium – Electrolytic Oxidation of Aluminium and alloys
With the help of our anodizing products, it is possible to anodize aluminium and common alloys in colour all by yourself. In this process, an aluminium oxide layer is created on aluminium surfaces in which dyes can be deposited on. After anodization, this previously porous layer is immersed in a dye bath and sealed by boiling. Anodised parts and surfaces can be found on many machine components, weather-resistant surfaces, electronic devices or lightweight components.
Warum Eloxieren?
Why anodize?
- Protection of aluminium by molecular compound
- Suitable for aluminium and many alloys
- Independent DIY process
- Multiple, combinable decorative colour effects
DIY application
With the help of our anodising products, you are able to anodise aluminium surfaces on your own. Several colours on one object are possible without any problems. The process is similar to electroplating. We offer detailed instructions, ready-made DIY sets and free product advice to make your project a success. Take a look at our guide to anodising before you start!
Colouring aluminium surfaces
Simplified, anodising is a kind of thickening or hardening of the aluminium surface. While in this process - comparable to the hardening of steel during forging - the surface first becomes porous and thus 'opens up', so-called anodised colours can be deposited in an effective manner. Anodising thus combines the pleasant (colouring) with the useful (corrosion protection).
Protect aluminium from corrosion
As soon as aluminium comes into contact with air, an approximately 0.1 - 0.5 µm thin oxide layer forms by itself. This natural layer protects aluminium from further attacks by oxygen, but does not withstand more aggressive conditions for long. To increase the protective effect and make the aluminium even more corrosion-resistant or weatherproof and scratch-resistant, it is sometimes anodised.
Anodizing explained in one video. Find more info on anodizing in our [guide].
What exactly is anodizing or anodising?
Anodizing is an electrochemical process for creating oxidic protective coatings on aluminium or metals. The specific treatment of aluminium is called 'anodizing'. Magnesium, zinc or titanium can also be anodised. In contrast to electroplating, anodising does not add a layer, but transforms an existing aluminium layer. This layer thus serves both as corrosion protection and colouring. As a base metal, aluminium reacts with oxygen from the air in its raw state, similar to iron. This causes a thin layer of aluminium oxide to usually form on the surface. This layer naturally protects the aluminium surface from corrosion.
What is the point of anodising yourself?
Anodising is a relatively complex process that serves two purposes at the same time: Hardening aluminium or making it more corrosion resistant on the one hand and selectively colouring aluminium parts on the other. We - as well as our satisfied customers - are of the opinion that with the appropriate knowledge and the right equipment, you can also anodise on your own at home. Be sure to take a look at our guide beforehand.
- With the help of anodising, aluminium surfaces are hardened.
- Anodising process makes the surface corrosion-resistant and longer lasting
- Aluminium is protected by molecular bonding
- Colour storage possible during the process with different anodising colours
The anodising process essentially involves 4 steps – rinse with water between each step:
- Pre-treatment: For optimal results, the right pre-treatment is crucial. For mechanical pre- treatment, the work piece is polished - for chemical pre-treatment, our products help.
- Anodising: In this step, the actual anodising process takes place, in which the aluminium work piece is anodised in the galvanic structure. As soon as the current flows, water is decomposed through electrolyses on the cathode. On the anode, the oxygen reacts with the aluminium and an oxide layer is formed.
- Colouring: During oxidation/anodising, pores are created on the aluminium surface which allows anodising colours to be deposited in this step.
- Sealing: In the last step, the pores of the work piece are sealed by boiling off. If colour has been deposited, it is firmly sealed into the surface.
It's all in the mix! The more anodising powder, the better.
The actual anodising happens one step earlier - namely during the electroplating process, when the oxide layer of the aluminium surface is 'opened' - but the most interesting thing is of course the colouring of the aluminium. After all, apart from hardening, this is the main reason why we anodise: to colour different aluminium parts in different ways. This can be particularly useful for machine components or other application-related parts.
The following applies to all our anodising colours: The choice of mixing ratio determines the degree of saturation of the colour. This means: the more anodising colour, the better. The maximum degree of saturation is reached at 10 grams per litre of water. More anodising dye then leads to excess and can no longer be absorbed by the water or aluminium surface.
Frequently asked questions
Which metals can be anodised?
Aluminium and titanium are suitable for anodising. We recommend our products exclusively for aluminium.
Which alloys are suitable for anodising?
Our products cover the majority of the most common aluminium alloys. However, the industry is constantly evolving. For an overview table of compositions suitable for anodising, please see our anodising guide.
Why does my black anodised workpiece turn dark purple?
In this case, the concentration of the colour solution is not high enough. We recommend 10g/L. Also possible: the alloy is not or only insufficiently suitable for anodising. You can find an overview table on this in our instructions for anodising.
How much current and what voltage do I need for my project?
When anodising, the surface area of the workpiece is calculated in dm² and multiplied by 1.5. This gives the necessary amperage for your project. As soon as you set this on your machine, the voltage regulates itself automatically.
Can the objects be contacted with the stainless steel clamps?
No. Only the aluminium piece and titanium wire may be immersed in the solution with the anodising bath. The alligator clips must not come into contact with the bath.