How do you paint aluminium correctly? Our guide outlines the steps and the best ways for different types of aluminium.
Can I paint aluminium without sanding it? Basically, this is not a good option, as the paint does not adhere properly. However, simple objects raise the question of whether you still want to risk it.
Is it possible to paint anodized allminium? Yes, but the effort should not be underestimated. The big problem is that you first have to grind off a very thick oxide layer.
Why are there so many different paints for aluminium? The varnishes differ mainly in terms of their respective uses. In particular, aluminium parts that come into contact with solvents or are exposed to heavy technical loads must have high-quality coatings.
Aluminium is used in many areas and proves to be durable and robust against environmental influences. A painting is therefore not absolutely necessary, but often for purely optical reasons. In case of heavy stress or contact with solvents, however, painting is absolutely necessary.
In our guide, you will receive tips on how to paint aluminium correctly and which special features must be taken into account depending on the application.
Step-by-step guide to paint aluminium correctly
1. Protection and beauty – the reasons to paint aluminium
Unlike iron, aluminium is corrosion-resistant and also very light. The popular material is therefore used in many different areas.
For example, the automotive and electrical industries are using aluminium on a large scale. However, the packaging industry also uses the material to coat products and thus make them resistant to water.
Since aluminium forms a protective layer of alumina, it is in many cases unnecessary to paint aluminium. However, the metal looks matte and dull due to the layer. Especially with decorative aluminium elements, it is therefore almost unavoidable to treat the surface.
In addition to the purely aesthetic reasons, however, lacquer also helps to make the material more robust and durable. This is always crucial when aluminium comes into contact with other metals, is supposed to be resistant to gasoline, or is permanently in the water.
Attention: The best way of treating aluminium in terms of protection is powder coating. However, you cannot do these at home.
2. Clean the surface before you paint aluminium
Good to know: Aluminium is the most common metal found in the earth’s crust. Nevertheless, the extraction requires a lot of energy, since aluminium is not to be found in pure form in nature.
However, before you reach directly to the spray can or the brush, the correct pre-treatment should be carried out if you want to paint aluminium correctly.
First, clean the corresponding parts,whether they are alloy rims, a bumper or a noble decorative shell.
The next step is to prepare the aluminium parts. If you want to paint untreated aluminium, you can now start directly with the application of the primer.
Otherwise, first grab the sander and sand the surface nicely smooth. It is best to start with a grain size of 180 to 240 and continue to grope slowly up to a very fine grain size of 1000.
Tip: For simple products made of an aluminium sheet, it is not worthwhile to have the effort of comprehensive preparation. Therefore, you can also start applying paint directly after rough cleaning.
3. Choose the right paint – these differences are available
Boat varnish should be very robust.
If you want to paint aluminium, you are quickly faced with the question of which paint is the right one. This is a very important issue, given the large price differences between the individual products.
In general, the Council is in this regard that the more expensive product is always necessary in case of doubt when the load is rather high.
In addition, you save yourself the previous primer when using a 2-component coating. However, you need to mix the supplied hardener exactly and process the mixture quickly.
Otherwise, you must always prime aluminum with a adhesion promoter. This adhesive ground ensures a good connection between aluminium and varnish.
Whether you prefer to use a spray can or use a brush depends crucially on the respective components. For many small struts, e.g. spokes on bicycles, the spray can is worthwhile.
4. Anodized aluminium – a special challenge
If aluminium parts are anodised, this results in a particularly robust oxide layer on the surface. This protects the material, but makes it much more complicated for all painting requests.
Even a layer of adhesion promoter can only be used if the aluminium has been thoroughly sanded beforehand. The oxide layer must therefore be removed as completely as possible before you can start painting aluminium.
Due to the extremely hard surface, the question arises here whether you really want to paint them. In case of doubt, it is a good place to leave the work to a specialist company with special tools.
Simple grinding machines, on the other hand, cannot do much to the robust oxide layer.
If you want to repaint powder-coated aluminium, the old powder coating should be removed first. However, this is extremely complex, so that a new acquisition often pays off here.
5. Paint aluminium – this is how to proceed step by step
Maintain drying times when painting aluminium.
If you have selected the appropriate varnish, cleaned the aluminium, degreased and removed the oxide layer, you can start.
It is best touse a paint roll when painting.This applies to both the primer and the coating application, as long as you do not use a 2K coating.
Distribute the paint by moving the roll in all four directions. This is how you achieve a uniform coating application.
As a rule, you will see some fine bubbles. To ensure that they do not lie down and do not create a cavity that impairs protection, you can then carefully brush over them.
However, pull the brush only gently from one side to the other.
The remaining brush traces disappear by themselves during the drying process, as the paint still contractes.
If you are not quite satisfied with the result, you can apply a second layer.
To do this, however, first take the fine sandpaper at hand, roughen the surface briefly, remove the dust and repeat the above steps.
Finally, you can seal the surface of the aluminium with clear varnish. This increases the durability even further.