The painting of aluminum and other non-ferrous metals is associated with some difficulties associated with rapid oxidation. Under the influence of oxygen, an oxide film forms on the material, which minimizes the adhesion of any coating, including varnishes and primers. Because of this, self-staining is often short-lived and does not look the best.
Anodizing
Despite the modern range of primers, they do not give the necessary effect, and the paint layer peels off at the slightest impact.
It is possible to improve the adhesion of the paint and the surface of aluminum using anodizing metal. This procedure consists in electrochemical or chemical treatment, due to which the oxidation rate decreases. Almost all non-ferrous metal products painted under production conditions go through anodizing on special devices.
Materials and tools
At home, you can also carry out this procedure or use special primers. Powder coating of aluminum with anodizing takes more time and helps to increase costs, but the result is worth the effort. First you need to prepare tools and materials, without which it is impossible to achieve a durable and high-quality coating:
- spray gun, roller or brush;
- fine grit sandpaper (necessary for matting an aluminum surface);
- packaging for accommodating the part to be processed;
- vinegar to dilute the paintwork;
- aniline dye;
- degreasing agent;
- ingredients for electrolytic composition (water, salt, baking soda).
progress of work
Painting of aluminum begins with the combination of ingredients for the electrolytic composition and the preparation of the solution. The amount of water should be sufficient to completely immerse the aluminum element. The resulting liquid is poured into two identical containers. Soda is poured into one of them in a ratio of 1 to 5 (soda and water, respectively), and salt in the same amount is added to the other. Then the liquid is mixed until the additives are completely dissolved. The next step is straining and combining the composition of the two vessels. The solution should settle, at this time you can grind the metal surface. Grease and dirt are removed with a cloth soaked in acetone.
Further, the individual elements are rinsed under running water and placed in a container with a solution. Rubber gloves must first be worn to ensure safety.
The negative terminal is connected to the container with immersed parts, the positive terminal is directly connected to the elements themselves. Anodizing continues for 2-3 hours until a bluish-gray tint appears.
Further, aluminum can be painted at home. The coloring composition consists of 1 liter of liquid, 20 grams of aniline paint and 2 ml of vinegar. The solution must be heated to 80 degrees with constant stirring. Products that have passed through the anodization procedure are placed in a container with a coloring composition for 15-20 minutes.
Aluminum painting: technology
Anodizing aluminum is optional. If necessary, you can do without this procedure, using a primer to increase the adhesion of paint and metal. Painting aluminum with a primer is carried out using the following materials and tools:
- kerosene, acetone and any other degreasing agent;
- special paint for metal;
- alkyd-based primer;
- sandpaper;
- roller or brush.
Painting aluminum at home begins with sanding the surface to increase adhesion to the primer. The best option is an abrasive with a medium spraying. After thorough grinding, the products are treated with acetone using a lint-free cloth. To protect your skin, use rubber gloves.
Next, a primer is applied to the surface. At the same time, it must be distributed quickly and immediately after processing, since the durability and reliability of the coating depend on this. It is recommended that a primer is prepared before sanding the surface. Leaks and irregularities that have arisen after applying the soil can be removed with sanding paper.
Aluminum is painted at least in two layers, and before applying each of them, the previous layer must completely dry.
Powder paints
A powder composition is also used for coloring aluminum. It provides a reliable durable coating in the form of a monolithic layer, not only decorating the material, but also reducing the likelihood of corrosion.
The first step is surface preparation. In industrial conditions, salt and dirt are removed from the parts, and then rinsed with water. In addition to standard degreasing, painting aluminum with powder paint includes phosphating, which increases the adhesion of metal and paint.
Then the elements are dried by high temperatures and cooled. Of particular importance is the polymerization process, which consists in applying a special polymer layer under air pressure. Work is carried out using an electrostatic spray gun, which forms the thinnest layer on the surface.
After applying the paint, aluminum products are placed in a special furnace and are heated to 200 degrees for 10-15 minutes. Curing of the layer occurs during metal cooling.
The use of specialized tools and furnaces complicates the process of painting with powder formulations at home, which is why it is often replaced with anodizing.
Powder coating is possible on any aluminum parts. This technique is most widely used for coating parts that are intended for use at temperatures up to 220 degrees.
Spray painting
Before applying this technology, standard material preparation is used, for example, as with anodizing. Among the features it is worth noting the need to maintain a sufficient distance between the surface and the spray can, as well as applying a large number of layers. From the moment of applying the previous layer, at least 20 minutes should pass, only after that it can be covered with the next layer of paint. The number of layers varies from the quality of the paintwork material and the operation of the part. On average, it can vary between 3-15 applications.
Features
It is important not to forget about the periodic shaking of the balloon, this will help to avoid streaks and stains. In some cases, clogging of the nozzle is possible. To clean it, turn the balloon over and spray the composition until a transparent composition appears.
After coloring, in the presence of residues, they must be removed to a place protected from exposure to sunlight. Used tools are cleaned with a solvent. Painting under aluminum is made in a similar way, regardless of the material used for work.
Types of paints
The final result is influenced not only by compliance with all the intricacies of the work, but also by the quality and characteristics of the selected paint. The most widespread are several options:
- Acrylic composition is resistant to damage, moisture and sudden changes in temperature. Paint is applied over the primer.
- Epoxy is made on the basis of special resins, thanks to which it has such characteristics as durability and strength.
- Aniline was originally created for the textile industry. This paint is optimally suitable for aluminum products that have undergone anodization. But it is not without drawbacks, in particular, the composition is characterized by low resistance to moisture and sunlight.