Protecting the body of the car from corrosion is not just a matter of aesthetics, but a necessity that prolongs the life of metal parts. Moisture, road reagents and mechanical damage create ideal conditions for the appearance of rust, which can destroy even strong steel in a few seasons. Use of the motor-painting It is one of the most effective and affordable ways to prevent this process by creating a reliable barrier between metal and an aggressive environment.
Many car owners mistakenly believe that factory coating or electroplating completely solves the problem. However, over time, factory materials lose their properties, and in the hidden cavities and on the bottom, corrosion foci begin to appear. Proper use of bitumen, rubber or polymer compositions allows not only to stop the processes that have already begun, but also to create a durable layer resistant to gravel shocks and chemical influences.
In this article, we will discuss in detail how to use mastic for cars to achieve professional results in garage conditions. You will learn about the types of protective materials, surface preparation features and application technology that guarantees protection for many years to come. A competent approach to this process will save significant funds on body repairs in the future.
Types of automotive mastics and their purpose
Before you start work, you need to understand the varieties of protective compositions, since the final result depends on the right choice. Bituminous mastics They are considered classics of the genre: they are cheap, affordable and perfectly insulate metal from moisture. However, they have a significant disadvantage - low mechanical strength. When struck with stones, such a coating can crack, and the moisture under it will lead to the rapid development of corrosion.
More modern solutions are being used polymer based on rubber and synthetic resins. They have high elasticity even at low temperatures, which prevents cracking. These compounds are often called βliquid underwingsβ because of their ability to absorb noise from wheel arches. For hidden cavities, where it is impossible to apply a thick layer, special penetrating compositions with rust inhibitors are used, displacing moisture.
The choice of material also depends on the processing area. For the bottom, thicker and stronger mixtures are suitable, and for arches - elastic.
- π‘οΈ Bitumen-rubber compositions: provide high adhesion and elasticity, ideal for the bottom.
- π§ Penetrating inhibitors: used to treat hard-to-reach places and welds inside sills.
- π¨ Polymer mastics: create a strong, impact-resistant coating, resistant to chips.
Necessary tools and surface preparation
The quality of application of mastic by 90% depends on the surface preparation. If you ignore this stage, even the most expensive material will peel off along with the rust in a couple of months. First of all, the car must be thoroughly washed, paying special attention to the wheel arches and bottom. Use active foam and high pressure wash to remove all dirt, oil stains and bitumen residue.
After cleaning, the surface should be perfectly dry. Moisture under the sealant layer is a guarantee that the metal will continue to rot. To speed up the process, compressed air or a heat gun can be used. Next is the mechanical cleaning step: all loose (flake off) areas of rust and old coating must be removed with a metal brush or scraper. If the rust is deep, you will need to use a rust converter.
To work, you will need the following set of tools:
- π§ Metal brushes, scrapers and sandpaper for cleaning.
- 𧴠Degreasing agent (White Spirit, acetone or special antisilicone).
- π« Pistol for application of mastic (for aerosol cylinders or professional sprayer).
- 𧀠Personal protective equipment: respirator, gloves, glasses.
Degreasing is a critical step. Apply the degrease to the rags and thoroughly wipe the entire treated surface. This will remove the invisible fat films and provide maximum adhesion (adhesion) of the mastic to the metal. Do not touch the fat-free surface with your hands.
βοΈ Preparation for mastication
Technology of applying mastic on the body
The application process requires compliance with the temperature regime. The optimum ambient temperature should not be lower than +10 Β° C, although some modern compositions allow you to work at +5 Β° C. Before use, the mastic can must be heated to room temperature (about 20Β°C) so that the material becomes more fluid and easier to apply. If you use a two-component formulation, mix the components immediately before use.
The application is carried out in several layers. The first layer is often made more liquid (you can dilute a little with a solvent if the instructions allow) so that it penetrates all the microcracks and pores of the metal. Allow the first layer to dry according to the time specified by the manufacturer (usually 2-4 hours), but do not allow it to dry completely before applying the second layer, otherwise the interlayer adg will be broken.
Etia. The second layer is applied thicker, forming the main protection. The thickness of the final coating should be 250-400 microns.When working with wheel arches, it is recommended to use floppy-platewhich create a noise-absorbing effect. For the bottom, you can use thicker bitumen mixtures that create an armored layer. It is important to evenly distribute the material, avoiding leaks that may not dry for a long time. If you are working with a sprayer, hold the gun perpendicular to the surface at a distance of 20-30 cm.
β οΈ Warning: Do not apply mastic to the hot exhaust elements, brake discs and calipers. High temperatures will cause the composition to ignite or boil, which is dangerous and inefficient. Close these nodes with paint tape or paper before starting work.
Pay special attention to welded seams and places of fastening of parts. This is where corrosion most often begins. Use a brush or thin spray nozzle to thoroughly miss each joint. After completion of the work, the car must dry in a warm, well-ventilated room for at least 24 hours until complete polymerization.
To check the quality of degreasing, drop a drop of water on the metal. If it spreads smooth film - the surface is clean. If it is going to drops - there are fat spots left, the procedure must be repeated.
Treatment of hidden cavities and hard-to-reach places
Hidden cavities, such as the insides of sills, spars and racks, are the most vulnerable places of the car. Moisture gets there through the process holes and stays there due to poor ventilation. Normal mastic will not fit here, since it does not have sufficient penetrating ability. Special services are used for this purpose ML-composites (oily liquids) with potent corrosion inhibitors.
The technology of processing hidden cavities requires special equipment - guns with a long spray nozzle. The nozzle is inserted into the process hole and the composition is sprayed under pressure, creating a fine mist that settles on all internal surfaces. It is important not to overdo it with the amount, so as not to create excessive pressure, but also not to regret the material.
Before processing, it is necessary to drill or clean existing process holes if they are clogged with dirt or previous anticor. After applying the composition of the hole should be closed with rubber plugs or glued to maintain a protective effect. The process is recommended to be repeated every 2-3 years, since oily compounds tend to gradually dry out or wash out.
- π³οΈ Use flexible nozzles to access the curved cavities of spars.
- π Orient by smell: if the smell of solvent went from the hole, then the cavity is filled evenly.
- π« DonοΏ½οΏ½οΏ½t use bitumen mastics for hidden cavities β they will clog drainage holes and create a βgreenhouseβ.
What happens if you donβt treat the hidden cavities?
Corrosion in the hidden cavities develops imperceptibly. The metal thins from the inside, and when the rust comes out, repairs are often no longer possible or require the replacement of entire body parts, such as spars or sills entirely.
Comparison of characteristics of different protective compositions
To make it easier for you to choose the right material, we have prepared a comparative table of the main types of anticores. Each of them has its advantages and disadvantages that must be considered when planning work.
| Mastic type. | Basis | Resistance to chips | Elasticity | Term of service |
|---|---|---|---|---|
| Bitumen | Petroleum products | Low. | Medium | 2-3 years |
| Rubber-bitumen | Bitumen + rubber | Medium | Tall. | 3-5 years |
| Polymeric | Synthetic resins | Tall. | Very high. | 5-7 years |
| Oil (ML) | Oils + inhibitors | N/D (liquid) | N/D (liquid) | 1-2 years |
As you can see from the table, polymer compounds benefit in durability and strength, but they are usually more expensive. Bitumen mixtures are a budget option for temporary protection or processing of cars, for sale. Oil compositions do not create a solid film, but remain liquid, constantly "healing" the metal, but require regular updating.
β οΈ Note: Do not mix mastics on different bases (for example, bitumen and acrylic). A chemical reaction can lead to swelling of the coating and loss of protective properties. If you do not know what the car was treated before, it is better to completely remove the old coating.
Common mistakes in anticorrosion treatment
Even with the availability of quality materials, beginners often make mistakes that negate all efforts. The most common of them is the application of mastic on wet or poorly purified metal. Rust under the layer of protection will not go anywhere, but only canned and will continue to destroy the body from under the coating. Always make a good mechanical cleaning.
The second mistake is ignoring the drainage holes. Covering them with a thick layer of mastic, you turn the cavities into water tanks. Water should be able to flow out. The third mistake is saving on the number of layers. One thin layer will quickly dry and crack, without providing proper protection. Follow the multi-layer application technology.
Many people also forget about the protection of paintwork (LCP) during work. Caught on the body bitumen mastic is very difficult to wash off and can damage the varnish. All areas that are not subject to treatment (glass, plastic, painted body parts above the thresholds) should be carefully sealed with paint tape and covering material.
- π« Applying to dirt: the coating will peel off along with the contamination.
- π§οΈ Working in dampness: moisture will remain under the mastic and accelerate corrosion.
- π₯ Overheating: Trying to quickly dry the mastic with a building hair dryer can cause it to swell.
The quality of anticorrosion treatment directly depends on the thoroughness of surface preparation. Saving time during the cleaning and degreasing phase will lead to rapid destruction of the protective layer.
Caring for the processed car and condition control
After the work, the car does not require complex care, but periodic monitoring will not hurt. Once a year, preferably before the winter season, it is recommended to inspect the condition of the coating in the wheel arches and on the bottom. If you notice deep chips or scratches that have reached the metal, these places should be locally cleaned and covered with a small amount of mastic.
When washing the car, use gentle modes for the bottom. Do not direct the jet of kerkerker under high pressure close to fresh processing in the first weeks after application, while the final polymerization is underway. For hidden cavities, the control is carried out visually through process holes or with the help of an endoscope, if possible.
Regular car washing in winter helps to remove aggressive reagents, prolonging the life not only of the body, but also the protective layer. A clean car rusts more slowly. If you operate the machine in harsh conditions, re-treatment of hidden cavities with oil compounds once every 2 years will be an excellent investment in the longevity of the body.
Can I apply mastic to rust?
The stain can only be applied to the surface of the stainless stain. A dense layer of rust (oxide film) some converters can conserve, but it is best to clean the metal to shine. If you apply mastic to loose rust, the process of rotting will continue under the coating.
How long does a car mastic dry?
The drying time depends on the type of composition, temperature and humidity. Usually, a surface film is formed in 2-4 hours. Full polymerization and strength set take 24 to 48 hours. In the cold season, the process can take up to 3-4 days.
Do I need to remove the wheels for processing arches?
It is advisable to remove the wheels for high-quality processing of the internal surfaces of arches and spars. This will provide access to all hard-to-reach places and will allow a uniform layer to be applied without passes. It will also protect the tires and discs from mastic hitting.
How to dilute a thickened mastic?
Bitumen mastics can be diluted with white spirit, kerosene or special solvents for bitumen. Polymer formulations require their own solvents (often listed on the jar), the use of inappropriate chemistry can destroy the structure of the material. Do not use gasoline or acetone for bitumen mastics unless indicated in the instructions.