How to prepare a metal surface for painting

Painting metal is a fairly common type of work. Due to it, the surface acquires a reliable protection and excellent visual effect. But to get a perfect result, the painting must be carried out with the observance of all technological nuances. They include the correct choice of material, preparation of the substrate and application of the paint composition.

What to paint metal with?

The right products are the key to success, which is why this factor is of paramount importance when working with metal substrates. And you can read about how metal laser cutting is done here.

Versatile materials

Painting can be carried out with the following common types of products:

  • For the manufacture of such compositions, silicone resins are used, which are supplemented with a hardener. Because of their high toxicity, they are used only for work outside. They differ in the complexity of application.
  • Oil-based. Traditional variant based on the organic substance. Prior to treatment with this composition, the metal is coated with a primer. Due to toxicity and acrid odor, details can be painted only with good ventilation.
  • Alkyd-based. Stable in demand in cases where it is necessary to treat metalwork. They are suitable for internal and external actions. If the substrate is well prepared and has no problems, the composition can be applied without prior priming.
  • The modern variety is based on polymers. Non-toxicity and ease of application ensure the popularity of the material. The composition is suitable for painting metal surfaces, subject to thorough preparation.
  • Used for exterior work, excellent for roofs or areas exposed to precipitation.

“These solutions are considered classic and are used everywhere. The powder coating method stands alone. It is complicated by the fact that it requires the use of special equipment and tools”, – Ягупов Геннадий.

On a side note! When choosing a suitable option, the flow rate, toxicity level, the necessary degree of preparation, durability, special properties and cost are also evaluated.

Specialized options

In some cases, special materials are required to ensure reliability and durability:

  • Compounds used in the presence of rust. These are epoxy varieties with special additives. They create a reliable film, preventing further deterioration. They are applied without pre-treatment of the base directly on the rusty areas.
  • To prevent corrosion. Such materials give the surface additional protection from moisture and oxygen, that is, they do not allow parts to rust.
  • Hammer compositions. Form an interesting decorative coating, resembling the marks of multiple hammer blows. They have a good resistance. Different variants of the base are used for production: epoxy, acrylic, alkyd.
  • Primer enamel. Universal variety of products, which combines a primer, corrosion protection and paint.
  • Forging mixtures. In their manufacture, polymer compounds are involved, which gives the coatings excellent wear resistance. Demonstrate good adhesion.
  • Nitro Paint. Sold in spray cans. Has a high toxicity.

There are also other kinds of paint mixtures – varnish and enamel, which are used in the treatment of stoves and other similar products. They are heat resistant materials.

Metal painting technology

The technological process is divided into several successive stages, which allows to achieve the best results.

Tools and materials

First of all, it is necessary to prepare the necessary tools and materials:

  • Dyeing composition.
  • When processing manually sheet products, a roller is used, for complex or hard-to-reach areas – brushes, with a mechanized method – a paint gun. If you need to paint a large area, it is very difficult to do it with a hand tool. But it should be taken into account that the sprayer is well applied only to the composition of a certain viscosity.
  • Priming compound. When working with an ordinary base, a simple solution for metal will do. If the product is made of colored materials, the appropriate primer is selected. In the case of the presence of rust, a primer-converter will be required. Its peculiarity is that it interacts with the damaged structure and turns it into a protective layer.
  • A separate container for the paint. It can be a container for a roller or a brush to simplify the procedure.

Be sure to read the instructions that come with each manufacturer. Particular attention is paid to the conditions of work. So, the minimum allowable temperature is +5 degrees with humidity no higher than 80%.

Preparation of metal surfaces for painting

This process requires a responsible approach, any shortcomings will be visible. To correct the problems caused by poor preparation is extremely difficult, and sometimes impossible.

Algorithm of action:

  1. The base is cleaned from dust and dirt, the remains of the old decorative layer is completely removed. When working with metal, it is better to avoid overlaying new paint on the old one, even if they coincide.
  2. Degreasing is an important step to improve adhesion. When working outdoors, it is necessary to protect the surface from dirt. The first rinse is done with solvent or white spirit: the entire area is treated, paying particular attention to hard-to-reach places. The next rinse is done with a warm soapy solution, which is then thoroughly removed with plain water. The result should be a clean and dry coating.
  3. If there are defects (cracks and depressions) that spoil the appearance, puttying is carried out. Beforehand, all treated areas are coated with corrosion-resistant compositions. Putty is applied selectively, only on the desired areas. The mixture is thoroughly distributed and flattened, and after drying is sanded. Should turn out a single plane without traces of repair.
  4. If there is rust, it is removed, with severe damage the converter is used. It is applied to the surface, cleaned of the main traces of corrosion. Due to the phosphoric acid, a reaction occurs, during which a protective film is formed.
  5. Minor damage is removed by grinding and sanding. The need to apply a primer depends on the chosen paint variety and type of coating. For example, galvanization should not be primed.

The preparation of the metal surface can be considered complete after all the steps have been taken and the substrate has dried.

How to paint metal products correctly

The methods of painting depend on the tools, a combination of tools is allowed.

Painting with a roller

It is convenient to work with a roller on large and flat surfaces. The technology is as follows:

  1. The composition is pre-diluted, a suitable substance is selected as a solvent. This procedure is necessary for easier distribution.
  2. The paint is poured into a convenient container. The roller should be immersed with a wide part, not sideways. The tool must be extremely reliable and not leave behind lint.
  3. The process begins with the selected area. It is better to move from one edge to another, this will avoid visible transitions.
  4. The moistened tool is placed on the surface, and then the rolling begins. The first movements are in the vertical direction: from bottom to top and back. At once an area two or three times the width of the roller is seized. The pressure should be minimal with a gradual increase.
  5. After the composition is transferred to the surface, the movements are replaced by horizontal movements.

The key to successful work is a smooth distribution of the material without too thick areas. The number of applied layers varies from 2 to 4.

Each subsequent layer is applied only after the previous one has thoroughly dried. Artificially accelerating the process is not permitted.

Painting with a brush

This is a rather monotonous activity, which is carried out on complex or embossed parts of the product.

If the mixture is too viscous, dilute it slightly. It is necessary to dip the bristles not completely, but on 1/3, this will avoid the appearance of runs, the excess is shaken off by tapping on the edge of the container. Movement should be unidirectional. The first strokes of paint is put on the coating, subsequent – rubbing. The number of coats applied depends on the type of surface.

Complicated structures are painted with thin brushes, with the minimum amount of the solution. This will eliminate the appearance of cured droplets.

Using a spray gun

Since the absorbency of metal is not very high, using a spray gun requires experience. If you don’t have any experience, you will need to practice.

Recommendations for operation are as follows:

  1. Spraying takes place without stopping. The first movements should be smooth and slow. The layer is laid in parallel.
  2. After the initial coating, the process is accelerated, the same place is treated in different directions. It is important to maintain the same distance.

This device greatly facilitates the work with their own hands. With some skill, it is possible to paint even difficult areas.

Note! If you want to get a surface with an antique effect, then resort to different methods. The easiest are considered to be painting under the bronze and glaze.

Powder coating

This process is very difficult to do at home, because you need a paint booth and special tools. But the advantage of this method is that after applying the paint the product is subjected to heat treatment, and this makes the coating more reliable and durable.

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