The appearance of red undertone on the welded sills or the bloating of paint on the wheel arches indicates that the electrochemical protection of the metal has already been broken and the oxidation process went deep into the structure. This is the moment when owners start looking for zinc-fishzinc compounds are able to stop corrosion by the method of tread protection, working as an active "sacrificial" layer. Unlike passive bitumen mastics, which only isolate the metal from moisture, zinc particles in the soil or spray take the first blow, oxidizing instead of iron.
Choosing the right composition becomes critically important, because the market is full of products with different content of active substances and the principle of action. Incorrectly selected material can not only not save the body, but also preserve moisture under the film, accelerating rot from the inside. Below we will analyze the physical principles of zinc-containing coatings, analyze the types of compositions and consider the application technology that guarantees the durability of the body of your car.
The principle of operation of zinc-containing coatings
The basis of the effectiveness of any zinc-anticor is a galvanic pair created between the iron of the body and zinc particles. Since zinc in the electrochemical stress series is left of iron, it has a higher oxidation potential. When electrolyte (moisture with dissolved salts) hits the damaged area, zinc first enters the reaction, protecting the base metal from destruction. This process is called cathode protection and it continues until all the active zinc in the coating is used up.
There is a misconception that any silver spray is a full protection. In fact, many formulations contain only microscopic amounts of zinc dust for color, working solely as a barrier coating. Real. zinc It must contain at least 90-95% high purity metallic zinc in dry residue to ensure full protective effect. If the percentage of metal content is low, the composition works only mechanically, blocking the access of oxygen, but does not react chemically to damage.
⚠️ Attention: Applying a zinc composition to a poorly rusted surface will cause corrosion to continue under the protection layer, since iron oxides do not conduct current and disrupt galvanic contact.
It is important to understand the difference between anode and cathode protection in the context of car bodies. Zinc coating provides precisely the anode protection of iron, becoming an anode in this galvanic pair. This means that even when chipping or scratching as far as metal appears, the zinc around the damage will continue to “sacrifice” itself, preventing the rust from spreading from the point of damage. That's why. zinc-filled soil It is considered one of the most reliable ways to prevent corrosion in aggressive environments.
Types of galvanizing: hot, galvanic and cold
When choosing a method of protection, it is important to distinguish between factory technologies and service procedures. Hot galvanizing, which is often mentioned in the advertising of new cars, is the immersion of body parts in a zinc melt at a temperature of about 450 ° C. This creates an extremely strong and durable connection, but it is technically impossible to replicate the process for a assembled car under normal service conditions. Galvanic galvanic galvanic (electrolytic) is also a factory method where the deposition of zinc occurs under the action of an electric current in a special solution.
Technology is used for secondary protection and restoration of the body cold-dip. This method involves the application of special compositions with a high content of zinc powder in a binder polymer to the metal. The binder (epoxy, polyurethane or alkyd) holds the zinc particles on the surface and provides adhesion, while the particles themselves create the necessary electrochemical potential.
Differences between zinc-containing soils from ordinary
Unlike standard acrylic soils, zinc-filled compounds conduct electric current. This is critical to the protection of the protection system. Conventional soils only insulate the metal, and when the layer is damaged, the rust quickly leaks under the paint. Zinc soil, even when damaged, continues to protect the metal around the scratch.
A comparative table of galvanizing methods allows you to better understand their applicability:
| Type of galvanizing | Process temperature | Applicability to the vehicle | Durability |
|---|---|---|---|
| Hot. | ~450°C | Only new details. | 50+ years |
| galvanic | 20-50°C (electrolysis) | Factory conditions | 20 to 30 years |
| Cold (spray/sound) | Environment | Repair and prevention | 10-15 years |
Thus, for the owner of a used car, only the cold galvanizing method is relevant. The quality of such protection depends on the surface preparation and the percentage of zinc in the selected product. Modern compositions allow you to create coatings that are close to galvanic in efficiency, subject to compliance with the application technology.
Types of compositions: single and two-component
The anti-cow market offers two main types of zinc-containing products: finished aerosols (single components) and professional two-component mixtures. Single-component formulations, such as popular sprays in cans, are convenient for local repair of chips, processing of welded seams and hard-to-reach places. They are ready for use, do not require mixing, but often have a smaller dry residue thickness and are more quickly consumed when processing large areas.
Two-pronged zinc-soil They are made up of a base (zinc powder in binder) and a hardener. Before use, the components are mixed in a certain proportion, triggering an irreversible chemical polymerization reaction. Such compositions form a much stronger, chemically resistant film that better withstands the mechanical effects of stones and sand. They are ideal for processing the bottom, arches and sills, where maximum reliability is required.
Main conclusion: For the bottom and arches, use only two-component professional compositions, and leave aerosols for spot repair of chips and seams.
When choosing a material, you should also pay attention to the type of binder:
- 🧪 Epoxy: They provide maximum adhesion and chemical resistance, but require perfect surface preparation.
- 🛡️ Polyurethane: They have high elasticity and resistance to shocks, which is important for the bottom.
- 💧 Alkyd: cheaper, dried faster, but inferior in durability and strength of the grip.
Therefore, you need to prepare them immediately before applying and in such quantities that you are guaranteed to have time to use.
Surface Preparation: Critical Stage
The effectiveness of zinc anticores is 80% dependent on the quality of surface preparation. The metal should be absolutely clean, dry and defatted. The presence of oxides, oils or old flaking coating will negate the work of even the most expensive zinc-containing composition. The first step is always mechanical cleaning: removing loose rust with metal brushes, sandblasting or using abrasive discs on drills.
After mechanical cleaning, chemical degreasing is necessary. For this purpose, special degreasings on silicone or alcohol basis are used, which do not leave a fatty film. White Spirit or gasoline "Kalosha" for these purposes are worse, as they can leave fatty divorces that worsen adhesion. Degreasing is carried out with clean rags, rubbing the surface in one direction and often changing the cloth.
⚠️ Attention: It is strictly forbidden to apply zinc soil on a wet surface or at a temperature below +10 ° C. Condensate, protruding on cold metal, will break the contact of zinc with iron.
☑️ Checklist for body preparation
If there are islands of dense, non-flake rust on the metal, some zinc-containing soils allow application on top of them (rust converter in the ground), but for maximum reliability it is better to remove the oxides completely to pure metal. The surface must be rough (risk) to provide mechanical adhesion (adhesion) of the first layer of soil.
Anticoric application technology
Application process zinc-anticor requires compliance with the temperature regime and the sequence of actions. The optimum air and surface temperature is from +15°C to +25°C. At lower temperatures, the composition thickens and falls poorly, at high temperatures it dries too quickly, not having time to form a high-quality film. Two-component compositions must be thoroughly mixed with a mixer for 2-3 minutes to a homogeneous state.
Application is made by airless spraying (brascopy) or brush in hard-to-reach places. When working with a paint track, it is important to choose the right pressure (usually 2-4 atmospheres) and the diameter of the duse (1.6-2.0 mm for zinc-containing soils). The first layer is applied with a thin "dust" layer to improve adhesion, the subsequent - a thicker, wet layer.
Tip: When processing hidden cavities, use special spray nozzles with a radial torch so that the composition settles evenly on the walls.
Usually, the technology requires 2-3 layers of interlayer drying. The drying time "on the stick" is 15-30 minutes, but full polymerization can take from 12 to 24 hours. Do not rush and apply the next layer on the sticky surface, this can lead to the formation of bubbles.
Common Mistakes and How to Avoid Them
One of the most common mistakes is to apply zinc soil on a glossy, smooth surface without first matting. Zinc-containing compositions require roughness for reliable adhesion. If you apply them to a smooth metal or old glossy paint, the coating can detach from the layers under the influence of vibration or temperature changes.
Another mistake is ignoring the compatibility of materials. Not all finishing coatings (enamel, varnishes) are friendly with zinc soils. Some types of paints can react with active zinc, causing swelling or color change. Always check the manufacturer's recommendations regarding compatibility with finishing enamel.
Also, there is often a violation of the proportions of mixing two-component compositions. Adding a hardener "on the eye" leads either to the fact that the soil will never dry (few hardeners), or becomes too fragile and cracked (many hardeners). Use measuring containers or scales for accurate dosing.
FAQ: Frequently Asked Questions
Can I apply zinc anticores over normal rust?
Technically, there are "3 in 1" compounds (converter + soil + zinc) that allow them to be applied to corrosion. However, for long-lasting protection, it is recommended to remove the rust mechanically to pure metal. Applying to rust reduces the service life of the coating by 2-3 times.
Do I need to paint the zinc soil from above?
Yes, I will. The pure zinc layer is porous and hygroscopic, it quickly oxidizes in air, covered with white coating. In addition, zinc soil is afraid of alkalis. Finish enamel or varnish create the necessary chemical and mechanical protection for the zinc layer itself.
How often should I update the anticores with zinc?
A qualitatively applied two-component zinc soil in the bottom of the car lasts 10-15 years. However, it is recommended to conduct an annual inspection of the condition of the bottom and arches. When deep chips to metal are detected, local restoration of the coating is necessary.
Is Zinc Spray Harmful to Health by Inhalation?
Yes, zinc aerosol and solvent vapor are bad for the lungs. When working with aerosols or paintsmiths, be sure to use a respirator with carbon filters and work in a well-ventilated room or outdoors.