Painting aluminum and other non-ferrous metals has some issues 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-coloring is often short-lived and does not look the best.
Anodizing
Despite the modern range of primers, they do not give the desired effect, and the paint layer peels off at the slightest impact.
It is possible to improve the adhesion of paint and aluminum surface by anodizing the metal. This procedure consists in electrochemical or chemical treatment, due to which the intensity of oxidation is reduced. 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 eitheruse special primers. Powder coating anodized aluminum takes more time and increases 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, roller or brush;
- fine grit sandpaper (required for matting the aluminum surface);
- container for placing the part to be processed;
- vinegar for diluting the paint composition;
- aniline dye;
- degreaser;
- ingredients for electrolytic composition (water, s alt, baking soda).
Progress of work
Painting aluminum begins with the combination of the ingredients for the electrolytic composition and the preparation of the solution. The amount of water must be sufficient to completely submerge 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), s alt is added to the other in the same amount. After that, the liquid is mixed until the additives are completely dissolved. The next step is filtering and connecting 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 the flowwater and placed in a container with a solution. You must first wear rubber gloves to ensure safety.
The negative terminal is connected to the container with the submerged parts, the positive terminal is connected directly 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 gone through the anodizing procedure are placed in a container with a coloring composition for 15-20 minutes.
Painting aluminum: technology
Aluminum anodizing is optional. If necessary, you can do without this procedure, using a primer, which allows you to increase the quality of adhesion of paint and metal. Aluminum painting with a primer is carried out using the following materials and tools:
- kerosene, acetone and any other degreaser;
- 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 would be an abrasive with a medium coating. After careful polishing, the products are treated with acetone using a lint-free cloth. For skin protectionhands must wear 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 depends on this. It is recommended to prepare a primer composition before starting surface grinding. Sagging and irregularities that have arisen after applying the primer can be removed with sanding paper.
Painting of aluminum is done in at least two coats, and the previous coat must be completely dry before applying each of them.
Powder paints
A powder composition is also used to color aluminum. It ensures the creation of a reliable durable coating in the form of a monolithic layer, which not only decorates the material, but also reduces the likelihood of corrosion.
The first step is surface preparation. In industrial conditions, s alts and contaminants are removed from the parts, after which they are rinsed with water. In addition to standard degreasing, aluminum powder coating includes phosphating, which increases the adhesion of metal and paint.
Then the elements are dried at 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 that forms the thinnest layer on the surface.
After applying paint, aluminum products are placed inspecial oven and heated to 200 degrees for 10-15 minutes. The layer cures as the metal cools.
The use of specialized tools and ovens complicates the process of powder painting at home, which is why it is often replaced with anodizing.
Powder coating is possible on any aluminum parts. This technique has become most widespread 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 in anodizing. Among the features, it is worth noting the need to maintain a sufficient distance between the surface and the can, as well as applying a large number of layers. From the moment of applying the previous layer, at least 20 minutes must pass, only after that it can be covered with the next layer of paint. The number of layers varies depending on 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 periodic shaking of the bottle, this will help to avoid streaks and streaks. In some cases, the nozzle may become clogged. To clean it, it is necessary to turn the can over and spray the composition until a transparent composition appears.
After painting is completed, if availabletheir remains must be removed in a place protected from exposure to sunlight. The tools used are cleaned with a solvent. Aluminum painting is done in the same way, regardless of the material used for the job.
Paint types
The final result is influenced not only by the observance of all the subtleties of the work, but also by the quality and characteristics of the selected paint. The most widespread acquired several options:
- Acrylic composition is resistant to damage, moisture and sudden changes in temperature. The paint is applied over the primer coat.
- Epoxy is made from special resins, thanks to which it has such characteristics as durability and strength.
- Aniline was originally created for the textile industry. This paint is best suited for aluminum products that have undergone an anodizing procedure. But it is not without drawbacks, in particular, the composition is characterized by low resistance to moisture and sunlight.
