Painting aluminum yourself at home

In this article we will talk about how and with what to paint aluminum so that the color lasts as long as possible. Despite the fact that most problematic metal surfaces can be covered powder paint, we will consider methods that are available for use at home, that is, in those conditions where there is no specialized equipment and expensive coatings.

Powder paint is a popular solution for processing aluminum

Features of painting aluminum

Powder coating

Painting aluminum parts, as well as other non-ferrous metals, is significantly complicated by the tendency to rapid oxidation. When interacting with oxygen, the metal is instantly covered with a thin oxide film, to which neither primer, nor paint, nor varnish properly adheres.

Important: When you start painting aluminum at home, be prepared for the fact that the result will be short-lived.
The situation is complicated by the fact that the problem cannot be solved by using most traditional soils.
It will be enough to scratch the layer of dried paint with your fingernail, and it will come off.

Are there any effective ones and what is important? available methods solutions to this problem? There are effective solutions and we will talk about them in this article.

Correct painting

Two-component putty with the addition of aluminum powder

Before properly painting aluminum, it must be anodized and thus significantly increase the adhesion of the surface to the paintwork material.

Anodization is a chemical or electrochemical treatment of non-ferrous metals, as a result of which the oxidation process is less intense than on a clean surface or does not occur at all.

Most factory products made of non-ferrous metals are anodized before applying paints and varnishes. Anodizing is performed using special high-tech equipment. But, as already said, we will consider available methods, which are relevant for implementation at home. (See also the article Types of finishes: options.)

There are two such methods, namely:

• staining with aniline dye with preliminary anodization;
• painting with acrylic or epoxy enamels without preliminary anodizing, but with the use of special primers.

We anodize first and then paint

In the photo - anodizing at home

If you don't know how to paint aluminum black in your home or garage, then this method is what you need. Of course, the technology is a little more complicated than painting in its pure form, but the result will be of the highest quality.

To obtain a rich and durable coating we will need the following materials and tools:

• an aluminum container in which the workpiece can be placed;
• fine-grained sandpaper to lightly matt the aluminum surface before applying paintwork;
• painting tool (brush, roller or sprayer);
• current source (12V/2A);
• materials for preparing an electrolytic solution (soda, salt and boiled water);
• kerosene or acetone for degreasing the surface;
• aniline dye, the price of which is low;
• acetic acid for diluting paint.

Schematic illustration of the anodizing process

The painting technology is as follows:

• Prepare an electrolytic solution. To do this, we determine how much water is required for the part to be completely immersed in it. Divide the liquid in half and pour into two different vessels.
  Pour into one of the vessels table salt in an amount of 1/5 of the volume of liquid. Pour the same amount of baking soda into another container. Mix the water in two vessels thoroughly.
  Next, we filter the solutions and pour them into one aluminum container and mix again, and then let them settle.
• At the next stage, armed with sandpaper, we carefully sand the surface of the product.
• Wipe the sanded surface with a cloth soaked in acetone. Thus, we simultaneously remove dust and degrease the surface.
• We put on rubber gloves, rinse the product in water, and then immerse it in a container with an electrolytic solution.
• We connect the power source with a plus to the product, and a minus to an aluminum container with an electrolytic solution. The process lasts for 2 hours until a characteristic grayish-blue tint appears.
• After preparing the metal, you can begin painting. To do this, mix 20 grams of aniline dye with 1 liter of water and 1-2 ml of acetic acid. Mix the solution thoroughly, gradually heating it to a temperature of +80º C.
• The anodized product is immersed in the diluted dye and left for 15 minutes.

Paint over a pre-primed surface

On the picture - alkyd primer for processing non-ferrous metals

In order to avoid anodizing, but without compromising quality paint coating, we use special primer compositions, which are capable of providing a high degree of adhesion.

To paint the surface of aluminum parts with your own hands without anodizing, you will need the following tools and materials:

• painting tool (brush or spray);
• sandpaper for matting the metal surface;
• special alkyd primer for application to non-ferrous metals;
• epoxy or acrylic paint for metal;
• metal degreasing agents (acetone, white spirit or kerosene).

The work is carried out as follows:

• We carefully sand the surface of the product, making it evenly matte.. For optimal results, use paper with abrasive size 1200.
• After sanding the metal, put on rubber gloves, soak a lint-free cloth in a degreaser and remove dust and dirt from the product. .
• Cover the cleaned part with a primer .

Important: The longevity of your paintwork will depend on how quickly you apply the primer.
Therefore, before you start sanding and degreasing, you need to prepare the primer so that you can subsequently apply it without delay.

• The dried primer can be leveled with sandpaper, after which we proceed to painting. .
• paints and varnishes Apply in 2-3 layers with the interval necessary for each previous layer to dry .

Conclusion

Still believe that best paint for non-ferrous metals – powder? In fact, this is not the case, since by conducting Painting works, in accordance with the previously given methods, you can achieve good results.

Have questions about painting? You will find comprehensive answers by looking at this article.

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Many non-ferrous metals are very difficult to paint. This is due to the fact that it is difficult for coloring compounds to adhere to the surface of metals, which leads to the need to implement complex technological painting procedures.

The above fully applies to aluminum.

How is this problem solved by industry?

In industry, various techniques for painting non-ferrous metals are used. Almost all of them imply very specific conditions. For example, a common method is to spray powder coating on metal under conditions high temperatures and pressure. In addition, technologies based on the electrochemical characteristics of the interaction of substances are practiced. IN in this case, the coloring matter is fixed on the metal surface due to the attraction of particles with different charges.

There are also less common methods of painting aluminum, but they are all characterized by one property - they are not suitable for home use.

What is the solution for home use?

Aluminum is quite widespread in household use. For example, a square aluminum pipe can be used as a supporting profile for various frames or a cable channel. You can also often find aluminum window blocks.

Is there really no way to paint all this at home?

Of course, you can, although the quality will be inferior to factory paint.

For work we will need:

• Special primer for aluminum or stainless steel;
• Sandpaper (the finer the better - best option 800 - 1200);
• Metal paint (acrylic or epoxy);
• Surface degreasing agent;
• Ventilated area without insects;
• Respirator.

The painting procedure is as follows:

• Surface treatment with sandpaper. The purpose of this action is to remove contaminants and a layer of oxide film that will interfere with the adhesion of paint to the metal surface. Fine paper is used to avoid causing deep damage to the metal (scratches).
• The treated surface is degreased using special means. Conventional solvents are not recommended.
• The treated surface must be coated with a primer. Moreover, it is recommended to do this quickly, otherwise the metal will begin to darken, which indicates the formation of a new oxide film. If it appears, you will have to clean the surface again.
  Some consider primer treatment optional, and argue that you can save money by starting painting right away (this is motivated by the fact that the paint is specialized - it will apply well anyway). In fact, the savings here are questionable: the primer reduces paint consumption and improves its adhesion to the surface.
  And, by the way, it is better to apply the primer in 2 layers.
• After the primer has dried, painting is done directly. We recommend using aerosol sprayers, as they ensure even distribution of paint and are generally easier to use than traditional brushes. Painting a square aluminum pipe with a brush in such a way that no drips form is extremely difficult.
• After the first coat of paint has dried, carefully inspect the surface. If drips are found, remove them with sandpaper. If you rub the paint down to bare metal, recoat this area primer.
• For a high-quality result, 3-4 layers of paint are needed, each of which dries for 4-6 hours.

Aluminum is difficult to paint due to the formation of aluminum oxide on the surface, which appears as white plaque. Aluminum oxides are very passive - they do not react with anything, including paint. Therefore, you need to choose a paint and primer specifically designed for painting non-ferrous metals or aluminum. And now more about how to paint aluminum yourself.

Electrochemical painting method

Oxidation process performed electrochemically or chemically.

In the electrochemical method, an oxide layer is achieved by passing current through an acidic electrolyte solution. And after that they are treated with chromium and covered with paint or varnish.

During chemical oxidation, aluminum is treated in special solutions of sodium bichromate, chromic anhydride, and potassium fluoride.

At home, oxidation is quite difficult. It is necessary to have certain skills and strictly adhere to safety rules when working with chemicals.

After obtaining a layer of oxide by oxidation, you can begin painting the aluminum. To do this, purchase aniline dyes in the store - powders used for dyeing woolen fabrics. The aluminum part is placed in a hot (50-60°C) solution of aniline dye and kept there for no more than 20 minutes. After painting, the part is removed from the water, dried and coated with colorless varnish.

Painting aluminum at home

If you need to paint aluminum at home, you should follow all painting steps very clearly and consistently. An aluminum product must first be cleaned, then degreased and primed, and only then applied paint. The quality of the primer and paint is of great importance in this process. It is important to choose a good primer “for stainless steel, galvanized coatings and aluminum.” Special two-component epoxy/polyester paints can be used for painting.

Use sandpaper to remove all old paint and white powder. WITH maximum speed Apply the first coat of primer before the aluminum becomes dull. The oxidation process of aluminum in air occurs very quickly, so it is important to apply the first layer of primer as quickly as possible, before oxides form. After applying the first layer, wait the time specified in the manufacturer's instructions. When applying the second layer, there is no need to rush.

Even if the primer package says that no surface cleaning is required for its application, it is better to do so. Freshly cleaned aluminum will adhere better to paint. The sooner after mechanical cleaning painting is performed, the better the adhesion.

Painting stages

How to paint aluminum at home step by step:
1. Clean the part with sandpaper No. 600 (320 is also possible, but 600 is better)
2. Degrease with a solvent (acetone or gasoline are not suitable!)
3. Prime with a quality primer for non-ferrous metals
4. Dry well
5. Lightly sand primer No. 800-2000. If the primer is damaged and comes to the surface of the metal, apply primer again and dry.
6. Degrease, wait until the solvent evaporates.
7. Apply paint in several layers (enamel for metal - aerosol, alkyd, acrylic).

If the paint is from a spray can, then apply the paint at the distance specified in the instructions, as if spraying several layers onto the surface. Apply the first coat, wait 15 minutes, then the second coat. And so on up to 4-5 layers. If a dripping “drop” forms, wait until it dries, sand with 2000 grit paper and coat the area with paint.

• While working with a spray can, shake it often and vigorously so that the paint mixes better;
• To ensure that the can works evenly and does not “spit”, turn it over with the sprayer down and press the sprayer until the stream becomes transparent, this will clean the nozzle;
• The higher the sandpaper number, the better the final result. After processing 600, you can finish sanding with 1200, 1500, 2000. The result will be excellent.