Desolder aluminum

Aluminum parts can be painted like other metal parts. However, in contrast to paint stripping of steel and stainless steel, aluminum is somewhat limited during stripping, as the light metal reacts very quickly in the air in a chemical reaction. In this article you will learn what to consider when painting aluminum.

The difficulty in working with aluminum

Aluminum has very specific chemical properties which make the aluminum processing by the layman somewhat problematic and even by poorly equipped craft shops. Conversely, machining techniques such as aluminum sheet painting and even aluminum sanding are a real challenge for the home user.

Different methods for stripping aluminum

First of all we would like to mention the basically possible methods of paint stripping:

  • thermal paint stripping
  • chemical paint stripping
  • mechanical paint stripping

The thermal paint stripping

In the case of aluminum, mainly chemical and thermal paint stripping is used. But even thermal paint stripping requires a lot of expertise to gently heat and cool the aluminum without weakening the material. Apart from the machines that are necessary for this purpose, this method is completely unsuitable for the private user.

Chemical characteristics of aluminum

Before we go into the chemical and mechanical paint stripping, we want to go into the specifics of aluminum. As you know, aluminum does not rust. For this, the light metal oxidizes on the surface. For this purpose, the bare aluminum must be only a few minutes in the air, it already reacts and forms an oxide layer.

Because of this natural oxide layer, products such as adhesives, paints, etc. adhere very poorly. If the aluminum is even to be galvanized, even the silicon contained in the corresponding aluminum alloys must be neutralized. This is achieved by pickling the aluminum. A significantly weakened form of pickling is the degreasing of aluminum.

Subsequently, a so-called conversion layer is then often applied. Basically, that's nothing more than an oxide layer. However, in this method, the properties of the oxidation layer are accurately adjusted. Thus, the conversion layer can be adjusted so that the surface is particularly rough. Then paints or adhesives hold much better on the aluminum.

Mechanical stripping of aluminum is unfavorable

Precisely for this reason, the mechanical stripping of aluminum components is problematic. Typical applications would be sandblasting, glass bead blasting or techniques such as grinding and polishing aluminum. However, the problem is always that any conversion layer that may be present is destroyed in these processing techniques.

The chemical stripping of aluminum

Therefore, for many aluminum parts only chemical paint stripping is used. However, it must not be forgotten that different stains for stripping aluminum can also attack the conversion layer. If that does not matter or is subordinate, in hardware stores and in the specialized trade, there are Abbeizprodukte for aluminum, with which you can paint.

However, if it is absolutely important to maintain or reposition an existing conversion layer immediately after paint stripping, you should definitely give the aluminum parts to a specialist chemical paint shop. Incidentally, chromating is also a technique for applying a conversion layer.

Tips & Tricks

When chemically peeling off, pay attention to what you use. Especially on the Internet, where many half-truths are spread, it is always possible to read about the stripping or pickling of aluminum with caustic soda - even though that can destroy the aluminum. Therefore, especially aluminum parts, which must have a particularly high stability, must be stripped from the specialist company; for example, aluminum wheels. Usually this costs no more than the purchase of possible chemicals and tools.

Video Board: How to solder aluminum.