Primer for aluminum: selection, use and application

Maksym
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Maksym June 13, 2017 Specialization: country construction, apartment renovation, landscaping of a personal plot, installation and connection of utilities.

The aluminum frame must be primed before painting.

Do you want to paint aluminum products with high quality? Even though this is not the easiest task, there is still a solution. To ensure that the paintwork lasts for a long time, a special primer for aluminum is used for painting. Next I will tell you how to use it correctly.

How to coat epoxy primer?

After the epoxy primer

The car body can
be coated
with any compatible types of auto enamels (for example, polyurethane or glypthal). It is not recommended to use the primer in combination with alkyd-urethane, polyvinyl chloride, alkyd-acrylic and other paints and varnishes.

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Painting aluminum parts

Anyone who has painted aluminum knows that this is not a very easy task. If you paint aluminum products without preliminary preparation, the paint will lay down in an uneven layer, unevenly, and after a short period of time it will begin to peel off. Paint does not adhere very well without the use of a primer because:

• aluminum has a smooth surface. This metal has a peculiar crystal lattice, due to which the surface structure is very smooth. When painting, the smallest particles of paint have nothing to cling to, as a result of which they lie rather poorly on the base, and after some time they gradually fall off;
• high surface tension. Aluminum is a complex metal; its molecular bonds create strong tension on the surface, causing the surface to appear very slippery, and at the same time as if greasy. A high surface tension significantly reduces adhesion, that is, the adhesion of the base to the paint and varnish material;
• aluminum has an oxide film. This metal in its pure form reacts very quickly with oxygen contained in the air, as a result of which a durable layer of oxide film appears on the surface. This layer, which is visible to the naked eye, is manifested by corrosion, which has a heterogeneous structure and poor adhesion to other materials, including varnishes and paints.

Important! The more time passes, the thicker the oxide film becomes, it takes the form of peeling, loose corrosion foci, they slowly spread over the entire surface, while the aluminum becomes thinner, and the surface layer affected by corrosion will fall off along with the paint applied to it.

Method of use

Before using the Nerzhalux primer, mix well until smooth. Application must be carried out on a dry surface that has previously been cleaned of rust, dust, dirt and oils. If there is rust on the surface, it should be cleaned to Sa 21/2 using the abrasive blast cleaning method. Application can be done using a roller, brush, airless spray or air tool. If necessary, the primer can be diluted to working viscosity, using solvents R-648 or R-5A.

How to properly prepare aluminum

In order for varnishes or paints to adhere perfectly to aluminum and adhere firmly to it, the base must be properly prepared before using a primer. When manufacturing aluminum parts at a factory, preparing this metal is a complex process, but even at home you can prepare aluminum well. Before using aluminum primer for painting, the following preparations must be completed:

1. Clean the surface mechanically. It is very important to remove dust, dirt, old paint and oxide film from the metal. The best tool for this cleaning is a sandblaster, but if you don't have one, you can use coarse sandpaper, a coarse file, or a sander with a special protective disc. Aluminum needs to be cleaned to a shine.
2. The base is degreased and etched. These procedures are needed to remove a continuous oxide layer, greasy, oil stains from a metal surface. Degreasing is carried out using alcohol, acetone or solvent. After this, small aluminum products can be dipped briefly into a plastic container in which phosphoric acid and water have previously been diluted. Large parts or structures must be coated with the same orthophosphorus solution using a brush or foam rubber. This procedure must be performed strictly with rubber gloves, thick clothing and goggles.
3. Creating a conversion layer. At home, such a layer can be created using zinc phosphate, which is applied to purified aluminum. Zinc phosphate does not undergo a corrosive process; it has a rough structure, so it is very suitable for smooth aluminum parts, providing a high rate of adhesion of the base to the paint and varnish material applied after priming.
4. Washing and drying. It is necessary to rinse the base to completely remove chemicals from it that would interfere with the application of the primer. After washing under running water, the product is dried either using a hair dryer or in the open air.
5. Applying primer. At this stage, the primer is applied in one or more layers. When the primer dries, the base will be covered with a polarized protective layer, which will become an excellent base for applying paint and varnish material.

Attention! Typically, primer for aluminum contains harmful and toxic components that have a detrimental effect on human health. To be on the safe side, the primer should be applied to the aluminum either in a very well ventilated room or outdoors. It is important to use personal protective equipment such as gloves, goggles and a respirator.

Preparation stages

To obtain a high-quality surface, you should perform a number of preparatory actions and adhere to a strictly proven algorithm:

1. First of all, you should prepare the room in which the body will be painted.
2. Then you need to clean the surface from rust, dirt, dust and old putty.
3. Next you need to inspect the machine and prepare a suitable enamel composition.
4. After this, it is necessary to protect the body parts that do not need to be treated and degrease the surfaces.
5. At the next stage, putty is applied and an anti-corrosion layer is formed.

Main varieties

You can find 2 types of acid soil on sale:

1. Based on 1 component.
2. Based on 2 components.

One-component

Phosphate primer based on 1 component can be used without prior preparation. It can be purchased in cans for application without auxiliary equipment or in containers with a liquid solution. The second option is applied with a spray gun in 1 thin layer. When the coating acquires the required properties, it can be treated with acrylic with the inclusion of a hardener.

Two-component

Before applying the product to a metal surface, it should be properly prepared. The instructions mention the need to mix the main substance with the activator. The final consistency takes on both hard and soft forms. Experts advise choosing the first option, as it creates a strong and reliable film over the entire treated area. It is allowed to apply primer in 1, 2 or 3 layers, observing the proportions and basic recommendations of the manufacturer. There is a 5 minute pause between reuses.

Acid primer for a car, when to use and how to apply

When it comes to acidic soil, names such as phosphating, etching, and reactive soil are heard. In this article we will look at whether there is any difference between these products or whether they are different names for the same type of soil.

Let's figure out when it is used and how acid primer “works” and what is the difference between one-component and two-component acid compositions. Acid primer is a primary primer, like epoxy primer, and is applied to clean metal (see the article “acidic or epoxy primer, which one to choose”).

Acid primer, by etching the metal, cleans it and slightly changes the surface to improve further adhesion of the filling primer, and also ensures the transformation of fine rust. The etching primer does not remove, but it stops corrosion from spreading.

It is important to remove all rust as thoroughly as possible. Residues that cannot be removed are affected by acidic soil.

Acidic, phosphating, etching or reactive primer?

All these names, one way or another, refer to soil that contains acid. In English, there are three different names for acid soils, which are also indicated on packages sold in Russia.

• etch or etching primer - etching primer,
• self etch/etching primer - an etching primer containing ingredients that immediately after the action of the acid are eaten into the metal, creating anti-corrosion protection,
• wash primer is a reactive primer that also contains an acid and, in theory, is intended to be applied to new metal, free of old putty and paint, to increase adhesion (especially non-ferrous metals, such as aluminum).

Primer application process

Depending on the type of primer, the technology for its application will differ.

1. The primer in the form of an aerosol is applied to a previously cleaned surface. Before applying the primer, the base is cleaned to a shine using sandpaper. Grease stains are removed with a rag soaked in alcohol or solvent. As soon as the base is completely cleaned, you should immediately begin applying a primer to prevent an oxide film from appearing. The can is shaken several times, after which a jet of soil is applied from a distance of 20-25 centimeters, at an angle of 90 degrees to the surface. To avoid drips, the spray head must be constantly moved, without stopping in one place. Half an hour after the applied layer has dried, it is advisable to cover it with another layer. This primer dries completely in about 2 hours, after which it can be painted.
2. Two-component primers are prepared in a plastic container that is resistant to acid. A container of about one liter is sufficient; the base and thinner are mixed in it in a ratio of 4 to 1. The mixed primer is left for half an hour, after which the solution is mixed and applied to the previously cleaned base.

The process of applying two-component primer is best done with a pneumatic spray gun, but you can use a regular foam roller. It is advisable to apply two layers, the second layer is applied after the first has completely dried. When the soil is dry, the product can begin to be painted.

Painting old coatings

The main issue when applying paint or varnish is the need to strip off the old layer. There is no need to strip off the old paint layer in the following cases:

• The coating does not peel off.

• Old material matches new material. That is, an identical alkyd can be applied to alkyd enamel without stripping the old surface.

In any other case, the old paintwork must be removed with organic removers. It is important to consider here that the removal technology must match the mechanical strength of aluminum. As soon as the wash is applied, the metal must be covered with polyethylene for half an hour. If the part is small in size, then it should be wrapped in a rag soaked in the remover. You can remove softened paint from the surface with a scraper made of plastic or wood.

Types of primers for aluminum

Nowadays, two types of primer are used to prepare aluminum for painting.

1. Aerosol primer for aluminum. This primer is supplied in cans; the aerosol is acid-free and is most often used for treating small aluminum products. It covers, for example, bicycle frames, car rims, etc. This type of primer is very easy to use; it can be used in the garage and even on the balcony. The primer is completely ready for use, dries in a couple of hours, but does not have high resistance to mechanical stress. Primers are sold in the form of aerosols in car dealerships and construction hypermarkets. When choosing such a primer, you need to look at the packaging; it should indicate “Primer for Aluminum” or “Alu Primer”. It is best if the composition contains zinc powder, in which case the package will be marked “Zn”. When choosing, you need to look at the production date and expiration date.
2. A two-component primer for application on aluminum is used to protect automobile bodies, aluminum boats, boats, and other products with a large area. One of the popular and effective two-component compositions is primer for aluminum VL 02. Two-component primers must be prepared in small portions. The prepared mixture must be applied no more than 6 hours in advance; it dries on the surface in about a day. After drying, a protective film is formed that has excellent mechanical strength and high corrosion resistance. The two-component primer includes an acid thinner and a base. The base contains polymer resins and zinc powder, which creates a conversion adhesive layer. The primer thinner VL-02 consists of special alcohol for degreasing the base and phosphoric acid, for etching aluminum and creating a phosphating protective layer.

Alternative primers

As mentioned above, primer and paint are two components that must fit together. But, since enamels are applied to a primer composition, we select them according to the principle of matching the primer for an aluminum surface.

The range of primers is quite wide, in addition to those considered, the following can be noted:

When choosing paints and varnishes, we advise you to purchase products from already proven companies. The compositions of such companies as Tikkurila, Hempel, Dukeson, Body and others have proven themselves well. Also, when choosing, always try to read the certificate, which displays all the necessary characteristics.

Consumption and precautions

Before purchasing a primer, it is important to familiarize yourself with the composition consumption, which can vary from 80 to 120 g/m2; this is true if the thickness of one layer is equal to the limit from 8 to 15 microns. Professionals advise applying about 2 layers. On sale you can find this primer, which is presented in a yellow base color. It is important to take precautions when applying this primer. When carrying out internal work and after its completion, it is necessary to ventilate the room, and in the process of applying the mixture, you must use personal protective equipment. The cost of one kilogram of such primer is 233 rubles.