Primer for metal: types, popular brands, features of use

One of the most durable building materials, which, however, also needs protection. We're talking about metal. To increase its service life and protect it from rust and mechanical damage, paint and varnish compositions are used that perform not only a protective, but also a decorative function. In order for the coating to hold firmly and maintain an attractive appearance for a long time, free from treacherous rust stains, metal surfaces are pre-primed. If you spend just 10 minutes reading this article, you will be able to get a general idea of ​​what types of metal primers currently exist, how they are applied, where they are used and how they work, as well as which ones are popular and what to consider, choosing the appropriate primer option.

What is a metal primer?

Answering this question, first of all, it should be noted that a metal primer in ready-to-use form is a suspension solution. The solvent can be different: water, oils, white spirit and other alkyd solvents.

Attention! If soils containing organic solvents are applied indoors, it must be ventilated. You should work in protective gloves, goggles and a mask.

In addition to soluble salts, there is a solid phase - a set of pigments and other fillers. Each composition has its own set of ingredients and its own characteristics, which determine where this soil is used.

Metal profile primer

When priming, both components that change the characteristics of metals (the ability to interact) and their oxides (rust reduction), and the hard film that the hardened primer forms can serve as surface protection. Priming solutions can be produced in one-component ready-made form or in two-component form. In the latter case, hardeners for film formation are added to the base compositions immediately before work.

Metal profile primer

Many primer coatings for metal surfaces can serve not only as protection, but also as an excellent base for subsequent topcoats. Anti-corrosion primers-enamels are also being produced and are becoming increasingly popular. These self-sufficient compositions have such important decorative features as color variety and the ability to choose the degree of gloss from matte to glossy.

To make it easier to choose primers and enamels for metal surfaces, in the next chapter we will give a short overview of their types.

Preparation for priming

Before starting to process metal surfaces, they must be cleaned. Dust, dirt, old paint, varnish or enamel - all this can be removed using convenient means at hand (metal brushes, abrasive brushes, spatula, etc.). If the metal structure being treated has already undergone corrosion, then the primer can be applied only after using the converter. Use paint softener to remove dried paint. It also contains anti-corrosion additives. After complete cleaning, the outer coating should be thoroughly washed and sanded. Large metal structures are polished with special machines. For small exterior work, use sandpaper of a suitable grain size and lint-free cotton cloth. The next step is degreasing the surface. It is carried out immediately before the priming process. The most suitable for this purpose are: White spirit, gasoline and other mixtures of similar composition. Degreasing is necessary for uniform coating of the metal and its maximum adhesion to the anti-corrosion mixture. If the surface has few defects with a greasy base, then you can limit yourself to local processing.

Priming process

In order to take into account all the nuances and do high-quality work, you need to master priming “in theory”: application, characteristics and material consumption. You need to prepare convenient tools, take care of your own safety measures, and become familiar with how to store the primer if you don’t use all of it.

Available means

The choice of tool for external application of primer depends on the form of release of the material, the relief of the metal coating, and its area. Possible options:

• · the roller is convenient to use for processing large and smooth products. It is easy for them to distribute the mixture of any consistency. The roller ensures economical application of the material;
• · It is advisable to purchase a brush if you need to prime a small external metal structure or treat hard-to-reach places. In other cases, its use will lead to increased material consumption and time;
• · spray guns come in different sizes and power, so they can be used to apply primer to any surface. They allow this type of external work to be carried out quickly, economically and with the highest quality.

A building materials store may offer you a primer solution in an aerosol can. This is a convenient option, but due to its low capacity it is unprofitable when it comes to covering a large metal structure. Regardless of the type of future work (external or internal), do not forget to purchase gloves, goggles and a respirator.

Applying primer

Correct distribution of the anti-corrosion mixture over the outer surface of the metal structure will avoid its overuse and obtain the required uniform protective layer of primer. Follow these guidelines:

1. work at temperatures from -10°С to +27°С;
2. Apply the solution in a thin layer. This facilitates its penetration into all irregularities and microcracks, rapid drying, and the creation of a durable film;
3. Applying each subsequent layer is possible only after the previous one has completely dried. The number of layers depends on the location of the external metal structure, its operating conditions (the more severe they are, the more material will be needed);
4. the final decorative finishing should be carried out within the next few days after the primer has dried. Otherwise, the outer surface of the product will begin to become covered with dust, which will significantly reduce the adhesion of the finishing material to the coating.

Remember: the importance of taking breaks during priming is solely due to the need for the protective material to dry completely. It must be purchased in advance in the required volume to avoid downtime. The information on its packaging will help you calculate the required amount of the selected primer: “Consumption per 1 m2.” By the way, if a frost-resistant composition is used, then its application should be preceded by the distribution of a moisture-repellent primer mixture.

Storage of soil mixture

Any type of paint or primer should be stored in a container with a tightly closed lid. They should not be left near heating systems, electrical appliances, or fire sources. It is recommended to store in places where direct sunlight does not penetrate, the temperature does not exceed average values, and ventilation air flows are provided. The finished mixture will gradually thicken in the container - it can be diluted with a solvent if necessary.

What types of primers are there for metal?

The answer to this question will depend on different evaluation criteria. Firstly, the release form. As mentioned earlier, the primer can be one-component or two-component. Two-component primers may not be so convenient to use, but among them there are completely unique ones with unique properties. For example, ship paint primer is an enamel primer of the Politex brand. Some of its modifications are even used to cover the hulls of ships that sail in ice conditions. One-component primers can be produced:

• as a solution in jars of different capacities;
• like spray cans.

Aerosol packaging tends to be more expensive.
Not long ago, a powder primer also appeared - a dry homogenized mixture: epoxy and polyester resin, pigments and additives. This primer has enhanced anti-corrosion protection. However, applying it at home will be problematic, since application requires special equipment and high-tech methods.

Primer treatment for metal

The second and main way to classify soils by metal is their composition.
For different soils, different solvents and different soluble and insoluble suspended pigments and fillers can be used. Table 1. The most common types of anti-rust primers.

A relatively new type is zinc-containing primer, which can be classified as a protective compound. The zinc content in it is 95-96%. In the zinc-iron galvanic couple, the more active zinc serves as protection. The base of the primer can be polyurethane, epoxy, alkyd, acrylic.

Primer treatment for metal with a roller

Of all the anti-corrosion primers listed in the table, alkyd compounds are especially worth noting, since they are now the most in demand and have the largest number of modifications suitable for a wide variety of applications.

Requirements

Why do you need a metal primer?

• The main goal is to ensure adhesion of a decorative or functional coating to the surface. The intermediate layer of soil provides reliable adhesion.

However: many paints (for example, heat-resistant silicone paints) are applied without primer. A layer between the coating and the metal will only increase the likelihood of delamination at a large operating temperature delta.

• In addition, the soil often has independent functionality: it provides anti-corrosion protection and prevents the destruction of the base by aggressive environments.

The main requirement common to all types of soil is reliable adhesion to metal. Some of the compositions are compatible only with strictly defined types of paints, while others are universal and can be used for any coating. Almost all of them use organic solvents: aqueous dispersions simply do not wet a smooth metal surface.

Features of alkyd primers for metal

The undoubted advantages of alkyd primers for protecting metal surfaces include the following properties:

1. High resistance to mechanical and chemical influences.
2. Alkyd primer is an excellent antiseptic. This is important, since mold and other types of fungi can settle on metal surfaces.
3. Excellent adhesion. Alkyd primers hold many topcoats firmly. This can be alkyd and acrylic paint, nitro paint, PVA glue and much more.
4. Alkyd primer is quite heat-resistant, and in the case of some compositions even heat-resistant. At the same time, it tolerates significant temperature changes. With its help you can reliably cover home heating radiators. For example, a thermal primer such as NOVAX GOODHIM primer-enamel is suitable. The protection will be especially reliable if high-temperature water-based acrylic enamel for GOODHIM radiators is then applied as a finishing coating, which retains its best performance at temperatures up to +100 degrees, with a short-term increase to +150.
5. Drying speed. In many cases, alkyd primer contains white spirit as a solvent, which, although it requires precautions, is not a highly toxic composition. This type of primer does not dry quickly. However, there are also quick-drying primers such as perchlorovinyl, which dries in one hour, polyvinyl acetate, which dries in half an hour, and others.
6. Increased water resistance. This feature is used in the production of alkyd-urethane primers-enamels, with the help of which automobile and other transport equipment, including its water-based varieties, are protected.
7. Highly decorative. Alkyd primer for metal, especially one produced directly on a varnish base, does not have to be colorless. It can be white, black, gray, brown, red, red-brown, yellow and any other color. As in the case of acrylic paints, the primer for metal can be white for tinting in pastel colors or transparent for tinting in rich colors.

Attention! You should always remember about the fire hazard of alkyd soils. The best fire protection measure for them is fire retardant paint applied as a topcoat.

Modifying primers against corrosion

Today, the paint and varnish market sells a large selection of primers that transform rust and provide excellent protective qualities.

Experts take into account the high demand for problems of slow destruction of metal structures resulting from rust. That is why they are developing various formulations that can prevent this phenomenon.

Most often, phosphoric acid is chosen as the base component. Some brands may contain hydroxycarboxylic acids, tannin and other components. When they interact with each other, they form a chemical reaction, due to which traces of rust dissolve, and in their place a dense coating is formed.

They are divided into several groups:

• Stabilizing types. Thanks to them, it is possible to accelerate the transformation process in the zone of unstable iron oxide hydrates. They transform the stable component of magnetite;
• Converters of corrosive products. Upon contact with a metal base, the main substances begin to destroy rust, resulting in the formation of phosphate salts;
• Penetrocin emulsions. This category has high penetrating properties. When applied evenly on an iron base, a chemical reaction is observed, during which a dense shell appears;
• Soil modifiers. Thanks to it, it is possible to create a reliable base before applying paintwork.

Such components can be selected only if the amount of rust or scale does not exceed more than 35% of the total area of ​​the metal structure.

In other cases, there is no 100% guarantee that a positive result will be achieved. There are compounds that can be used to treat rusty areas. It is recommended to properly prepare the surface first. To do this, large elements of rusty traces are removed from it, and then primer is applied.

Why do you need a primer for metal?

If we answer this question in detail, it turns out that treating metal surfaces with a special primer can give the following positive effects:

1. Protection of metals from corrosion. This is especially true for ferrous metals, which include cast iron, steel and other alloys containing iron.
2. Improved adhesion. Any enamel or varnish on a primer will stick much stronger and will not crumble under the influence of bad climate. This is especially important for galvanized iron and steel, as well as for non-ferrous metals and their alloys, which are difficult to rust, but even more difficult to coat without a primer.
3. Like any other primer, metal primer masks minor defects, that is, smoothes the surface. This circumstance leads to significant savings in finishing enamels and varnishes, which, as a rule, are more expensive than primers.
4. In addition to protection against corrosion and other chemical activity, metal primers enhance their mechanical strength.

Thus, if you choose the right primer, taking into account all the features of interior or exterior work, you can significantly extend the service life and improve the aesthetic performance of building structures, plumbing equipment, cars and other objects made of metal around us.

Spraying primer on metal

Choosing paint for metal

Traditionally, oil paints were used to paint metals. Now, with the advent of modern primers, you can use acrylic paints, both regular and those that are diluted with water, as well as paints on epoxy and alkyd bases. But don't use regular water-based paint, you need those that contain anti-corrosion additives, or better yet, paints that contain rust converters and form a dense coating.

Such paints, of course, cost more than conventional alkyd or oil paints, but you will save money due to their durability. These paints have high elasticity, which does not change over time.

How to apply primer on metal?

Before answering this question directly, it is necessary to recall the correct choice of the necessary product, which should suit:

• for black and/or non-ferrous metal;
• under external conditions: indoors or outdoors; the possibility of special chemical or mechanical influences; the likelihood of increased humidity, temperature, etc.;
• for painting with a finishing coat.

You should always carefully read the manufacturer's instructions, which describe in detail: how to apply the primer correctly, material consumption, what methods are used, whether it can be applied over rust, how long it takes to dry, what the total thickness of the layer should be, what can be used to dilute the working solution if necessary. It is most often necessary to dilute the primer so that it can be applied with a spray gun, because in this case more liquid mixtures are needed than, for example, when applied with a brush.

Before applying primer, the surface must be completely cleaned and degreased.

Do not forget that transformative compounds are not independent. With their help, rust can be easily removed, but then a passivating primer must be applied to the surface.

The primer is applied to metal surfaces with a brush, roller or spray. Each layer should be as thin as possible: two successively applied layers are always stronger than one of equal final thickness. Before painting with the finishing coat, the primer must dry thoroughly. If necessary, it can be given some roughness using sandpaper.

Spraying primer on metal

All of the above activities cannot be called labor-intensive. It’s better to definitely do them. If you are ready to take a risk and check what happens without a primer, you will be in for an unpleasant surprise, as well as additional material and moral costs.

Composition and technical characteristics

The main components that make up a rust primer:

1. Solvent.
2. A substance that serves as a binding element.
3. Plasticizers to improve adhesion, effectiveness of metal surface protection, etc.
4. Coloring pigment.

The characteristics of primers, including products applied to rust, depend on the components. The main qualities of such substances are conditional viscosity, the proportion of non-volatile ingredients, bending elasticity, impact resistance, hardness, adhesion in points, resistance to temperature changes.

Consumption per 1 m2

This indicator depends on the condition of the metal part to be processed, the number of corrosion spots, the depth of rust damage and other nuances. Average primer consumption for metal against rust:

• Primary priming, with the exception of compositions based on epoxy resin - 150-350 ml per square meter.
• Treatment with a rust primer based on epoxy or alkyd resin - 110-160 g per square.
• Using a universal composition – 80-140 ml per meter of surface.

Important! The indicated figures may vary, so when calculating the amount of substance for surface treatment, it is better to round the result up. Buying a rust primer with a reserve will allow you to avoid an unpleasant situation when there is not enough product in the midst of processing.

What is the best primer for metal? Popular manufacturers

There is no clear answer to the question of which primer is best for metal. Because, firstly, primers for metal have different purposes. Secondly, preferences vary from person to person. The best primer is the one that meets the desired requirements better than all others.

Tikkurila OTEX

SPECIAL METAL Primer

NOVAX Anticor “3 in 1” glossy

GF – 021

PF – 021

Nerzhamet

PRODECOR

Spray KUDO

The production of primers that protect metal surfaces is constantly developing, both abroad and within the country.
Domestic manufacturers are constantly improving, using both foreign experience and their own unique developments. And as this process intensifies, buyers are increasingly choosing domestic goods. Table 2. Popular primers for metal from leading manufacturers

It is worth noting that reviews of the presented products are approximately equally positive, regardless of whether it is a foreign or domestic brand. At the same time, the prices offered by domestic manufacturers are much more pleasant.

Advantages and disadvantages

The properties of an acid primer are considered its advantages. These include:

• high degree of wear resistance;
• enormous resistance to moisture and salt compounds;
• reliable protection of the material from external negative influences;
• excellent heat resistance – at high temperatures the qualities of substances do not change;
• fast hardening – within 5 minutes;
• resistance to the destructive aggressive influence of petroleum products, such as engine oils and gasoline.

In addition to numerous advantages, there are also disadvantages of the material. For example, it burns well. In addition, it is toxic, and when working with it you must work carefully and avoid contact with the skin and eyes.

When working with acid primer, protective equipment is required Source www.landspeedauto.com

Where can I buy the right primer for metal?

The answer to this question is a continuation of the previous topic. You can now easily find out how much a particular metal primer costs and what its rating is from the Internet. Just scroll through the pages of online stores and study the current prices for the products you need. To compare the results, all numbers must be reduced to a common denominator. That is, the comparison should not include the price per package, but the price per 1 kg or price per liter.

Attention! Since Russia is one of those countries where there are still a lot of counterfeit goods, including metal primers, you should only buy the latter in reliable stores.

A particularly reliable way to purchase is through the website of the manufacturing company. On our website you can find out all the technical details of the product, as well as the real cost - what retail and wholesale will cost. All prices without intermediary surcharges. The company works using the most modern materials from the best suppliers, as well as advanced technologies, including organizational ones, such as contract manufacturing. GOODHIM specialists are always ready to dialogue with clients and can choose the most advantageous offer for each.

What is the difference between acid primer and epoxy primer?

Epoxy primer is a substance that includes epoxy resin, fillers, polymers, and some alcohol derivatives. The primer, after application, creates a film that does not allow oxygen to pass through. After hardening, the soil does not allow water to penetrate at all, since it does not form pores. Epoxy primer is available in a can or in jars.

Epoxy primer in cans Source sevparitet.ru

Epoxy Primer Differences

According to experts, epoxy primer should be applied directly to clean metal and then putty. This is especially important if the metal is being restored over several weeks, i.e. for a long time.

For example, if a car sits in a garage for a long time, then, since there is humidity in the room, the areas of the body that have been stripped down to metal will begin to oxidize. In this case, you can choose the option of puttying with an epoxy primer. Then the putty should be applied before the primer has completely hardened.

Differences in acid soil

When it comes to acidic soil, you can hear the following names: phosphating, etching, reactive. The primer in this embodiment is a compound of zinc and phosphoric acid. More precisely, it consists of:

• polyvinyl butyral, which is a synthetic material and serves to form good adhesion and film;
• zinc phosphates and chromates;
• water;
• phosphoric acid, which is an excellent rust converter;
• alcohol.

Composition of acidic soil Source strport.ru
The operating principle is approximately this: phosphoric acid acts on the metal and, at the same time, zinc is precipitated. The film is formed by polyvinyl butyral - the acrylic layer will already adhere tightly to it. After applying the primer to the metal surface, a thin coating is obtained. It is an anti-corrosion and adhesive layer. The primer does not completely destroy the rust that is already there, but it also does not allow it to spread.

Acid primer for cars is divided into four main types:

• One-component.

Acid primer is often sold in a can to make processing easier. You can also use a can of primer to spray it with a spray gun. The composition does not need to be prepared - it can be used immediately. When the soil hardens, you can begin to treat it with an acrylic composition to which a hardener has been added.

• Two-component.

If you purchase a two-component primer, you must prepare a primer. To do this, it is mixed with an activator, and the consistency can be different - hard or soft.

Two-component primer Source autocosmetica.by

See also: Catalog of companies that specialize in paints and varnishes.

Professionals prefer to work with a solid form, as it gives the strongest film. Depending on the recommendations in the instructions, the two-component composition can be applied in 1, 2, 3 layers. During treatment, maintain an interval of approximately 5 minutes between applications.

• Reactive.

This option is used for clean surfaces. The reactive substance forms a very small layer (8-13 microns). This is the base on which the following layers should be applied.

• Self-Etching primer.

This substance is a soil with the addition of zinc. Used to eliminate unevenness and improve the quality of adhesion. The substance acts on the metal, resulting in the creation of a layer of frozen polymer elements.

Self-Etching primer Source alicdn.com

You can choose a one- or two-component primer, but most craftsmen use a material that has two ingredients. The greatest wear resistance is achieved through filler primer - this is a necessary stage of coating.

Tips and recommendations for use

• Don't buy the first priming mixture you come across. To make the right choice, you need to carefully study all the characteristics of the metal.
• In some cases, for better protection, it is recommended to apply a layer of moisture-proof coating. As a rule, this is done when using a frost-resistant composition that is used to treat objects located in the fresh air.
• Stick to the temperature regime. Regardless of the selected primer, it must be applied at temperatures from -10 to +27 degrees Celsius.
• Despite the specifics of priming, carry out the work wearing personal protective equipment. Take care in advance about purchasing glasses, a respirator and gloves. Wearing protective equipment is extremely important when using a sprayer.
• Observe the operating conditions of the soil, do not use it after its expiration date.

Application Features

In order for the primer to perform its functions as effectively as possible, it must be applied correctly. It is important to adhere to the following recommendations:

• Before you start applying the mixture to the metal surface, it is important to thoroughly clean it of any contaminants, including remnants of old paint, dirt, traces of corrosion and rust. If a rust converter is used, it does not need to be removed from the surface;
• when old, dried paint is very difficult to remove from the base, you can use a special softener. When it is applied to old paint materials, they are very easy to clean off the surface;
• When all contaminants have been removed, it is important to sand the base until it shines, and then rinse it. If non-ferrous alloys are processed, they do not need grinding; it is enough to wash and dry them well;
• Before you start priming the metal, if necessary, you need to degrease the base; this should be done in the presence of greasy, oily stains. Degreasing is carried out either with special electric machines or with ordinary cotton cloth and degreasers, such as solvents. Thanks to this procedure, the metal adhesion rate will be significantly increased;
• After preparing the base, priming of the metal begins on a clean and dry metal surface. The primer liquid is distributed over the base in a thin layer; puddles or drips should not be allowed to appear. When the first layer has dried, subsequent layers can be applied. Experts recommend applying two thin coats rather than one thick coat of primer;
• After the last layer has completely dried, you must immediately begin treating the structure with finishing paints and varnishes. If this is done after a few days, dust may settle on the surface, which will significantly reduce adhesion, and the quality of adhesion of the paint to the product will deteriorate.

If you follow the stages of performing the above work and carefully, slowly prime the metal base, the metal structure will be qualitatively protected, its service life will be significantly extended, and the metal surface will receive high-quality protection from aggressive and adverse environmental influences.