Corrosion of metal elements of the body is not just an aesthetic problem, but a serious threat to the safety and integrity of the car. Thresholds, being a force element, are subjected to enormous loads and aggressive influence of the external environment. Water, salt and reagents from roads get inside hidden cavities where lack of air access creates ideal conditions for the development of rust. That is why the question of how to handle the thresholds from the inside becomes critical for every owner who wants to prolong the life of his vehicle.
The process of internal protection is significantly different from external painting or application of protective compositions on visible parts of the body. It requires special materials that can penetrate into microcracks, displace moisture and create an elastic, self-tightening film. The wrong choice of remedy can cause corrosion to continue under the layer of protection, turning the metal into dust long before the defect becomes visible from the outside.
In this article we will analyze in detail the chemical composition of various anticores, the technology of their application and the specifics of the preparation of the internal cavities of the thresholds. You will learn about the differences between oil and wax formulations, and understand why some popular methods may not be effective in the long run. Competent approach to this stage of maintenance will avoid expensive body repairs in the future.
Causes of hidden corrosion
Understanding the physics and chemistry of the metal breakdown process helps you choose the right defense strategy. Inside the sills often accumulates condensation, which is formed due to temperature changes. In winter, the car falls from the cold into a warm garage or sink, and the moisture settles on the cold metal. If this condensate cannot evaporate due to structural features or clogged drainage holes, an irreversible oxidation process begins.
An additional factor of aggression is road reagents. Salt solutions, getting through technological holes or microcracks in the LCP, create an electrolyte. In combination with moist air inside the cavity, this turns the threshold into a kind of galvanic pair, where the metal acts as an anode and gradually dissolves. The speed of this process depends on the humidity, temperature and the presence of mechanical damage from the inside.
⚠️ Warning: Frequently washing rapids under high pressure without further drying can drive water deep into hidden cavities, accelerating corrosion if internal protection is compromised.
Another reason is abrasive wear. Sand and small stones flying from under the wheels, work like sandpaper, stripping the factory anticor or primer from the inner surface of the metal. The exposed metal reacts instantly with oxygen and moisture. Hidden corrosion It is dangerous because visually it becomes noticeable only when the structural integrity of the element is already broken and the paint bloats begin outside.
Classification of anticorrosive compounds for internal cavities
The automotive chemistry market offers many solutions, but not all are suitable for internal cavities. The main division occurs on the basis of the composition: oil, wax and polymer. Oil formulations, often referred to as “working out” or specialized oils, have excellent penetrating power. They do not dry completely, remaining in a liquid state, which allows them to constantly tighten microcracks and displace water.
Wax compositions create a denser, but less elastic film. They are good at protecting against mechanical damage, but they can crack when there are strong vibrations or impacts. Moisture enters the formed cracks, and local corrosion begins under the layer of wax, which is difficult to detect. Polymer compositions, in turn, create a very strong coating, but require perfect surface preparation, otherwise they will peel off along with the rust.
- 🛢️ Oil anticores: Ideal for older cars and severely damaged surfaces, as they impregnate rust and stop its development, but require regular updating.
- 🕯️ Wax compositions: They are suitable for new cars or after high-quality body repairs, create a solid protective layer, but are afraid of mechanical damage.
- 🧪 Corrosion inhibitors: chemical additives, often included in anticores, which slow down the chemical reaction of metal oxidation at the molecular level.
When choosing a tool, it is important to pay attention to its adhesion (metal adhesion) and thixotropicity (the ability to maintain viscosity at rest and liquefy when moving). For the internal cavities of the thresholds, compositions based on the lansoline oil Or synthetic resins. They do not dry out over time and do not crack in the cold, providing long-term protection even in harsh climatic conditions.
Technology of preparation of the inner cavity of the threshold
The quality of anticorrosion treatment is 80% dependent on surface preparation. Applying anticory to dirt, moisture or loose rust will not give any effect. The first step should always be a thorough washing of the inner cavity. For this purpose, special spray nozzles are used, supplying water under pressure, which washes out sand, salt and old dirt.
After washing, it is necessary to ensure complete drying of the cavity. Moisture is the main enemy of anticor. If you apply the protective composition on the wet metal, the water is preserved under the film, and corrosion will continue with a double force. For drying, compressed air or heat guns are often used, directing the flow of hot air inside the rapids through the process openings.
☑️ Preparation for processing
If there are foci of severe corrosion inside, mechanical cleaning or the use of rust converters may be required before applying the main anticor. However, in hard-to-reach places, mechanical cleaning is often impossible, so they rely on the chemical properties of oil compounds that are able to penetrate rust. It is also important to blow and clean the drainage holes to ensure natural ventilation and water outflow in the future.
Equipment for anticoring
For high-quality processing of thresholds from the inside of a conventional can with a tube, as a rule, is not enough. The pressure in the aerosol cylinder is not enough to uniformly cover the entire area of the inner surface, especially in corners and hidden pockets. Professional handling requires the use of pneumatic pistols with long flexible hoses and special spray nozzles.
Such nozzles, often called “rods” or flexible spokes, are inserted through process holes in the body. At the end of the spoke is a nozzle that sprays the composition at a 360-degree angle when moving back. This allows you to create a uniform layer of anticores along the entire length of the threshold. The use of the compressor provides the necessary pressure for fine spraying, which is critical for the penetration of the composition into all the slits.
In some cases, when using thick mastics, it may be necessary to heat the composition to the working temperature. This improves its fluidity and penetrating ability. However, with temperature, you need to be careful: too hot composition can damage rubber seals or plastic elements located inside the door or threshold.
Use transparent anticores to visually monitor the presence of the composition and the absence of air traffic jams in the spraying system.
Comparative characteristics of popular means
The choice of a particular product depends on the condition of the car and the owner’s budget. There are many brands on the market, from budget domestic to premium imported. To structure the information and help you decide how to handle the thresholds from the inside, we have compiled a comparative table of the main types of formulations.
| Type of composition | penetrating ability | Durability | Mechanical resistance |
|---|---|---|---|
| Oils (Movil, Dinitrol ML) | Tall. | 1-2 years (requires updates) | Low. |
| Body 930 (Liqui Moly) | Medium | 2-3 years | Medium |
| Polymers (Krown, Rust Check) | Tall. | 3-5 years and more | Tall. |
| Bituminous mastics | Low (surface only) | Tall. | Tall (but cracking) |
Bitumen mastics, popular in the past, are not considered the best choice for internal cavities today. They tend to dry and crack, after which moisture accumulates in cracks, and the metal rots under a hard crust. Modern. thixotropic They're devoid of that flaw. They remain elastic and do not require complete cleaning of the old layer during re-processing, which greatly simplifies maintenance.
When choosing a brand, you should focus on the specialization of the manufacturer. Companies that produce chemicals specifically for corrosion protection (e.g., Nova, Prim, Movile), often offer better solutions than universal brands of autochemistry. It is also important to read the instructions: some compositions are only for hidden cavities and are categorically not suitable for the bottom or arches, and vice versa.
Common errors in self-processing
Trying to save on the services of professionals and conduct processing on their own often leads to the opposite effect. One of the most common mistakes is applying anticores to a wet surface. As mentioned earlier, it preserves water from the metal. The second mistake is the use of too thick compositions without proper dilution, because of which the anticores do not penetrate into microcracks, but lie “coat” on the surface.
The third mistake is ignoring the technological openings. There are special drainage holes in the sills for water drainage. With careless processing, they are often filled with sealant or excess mastic. As a result, the water that gets inside stays there forever, turning the threshold into a tank of rusty slurry. Never seal drainage holes during anti-corrosion treatment!
It is also a mistake to treat only visible parts or places where rust has already appeared. Anticores should be applied preventively, on pure metal, or use compositions that work on rust, but with the understanding that this is a temporary measure. The lack of regular monitoring and updating of the layer also negates all efforts, since any anticores lose their properties over time.
Frequency of processing and condition control
Anticorrosion treatment is not a one-time procedure, but part of regular maintenance of the car. Even the most resistant compositions require verification. It is recommended to inspect the condition of the thresholds and hidden cavities at least once a year, preferably in the spring, after the winter season of operation.
If you use oil compounds, their service life can be only one season, especially in conditions of active driving on the road or off-road. Wax and polymer coatings last longer, but they are also prone to aging. The control can be done visually through drainage holes with a flashlight or using an endoscope connected to a smartphone, which gives a more accurate picture of the state of the metal inside.
⚠️ Note: If you find that the anticores have darkened, become sticky, or completely disappeared in certain areas, you should immediately re-treat these areas.
Regularity of processing also depends on the storage conditions of the car. Cars stored in dry heated garages require less frequent handling than those that sleep outside or in damp unheated parking lots. In any case, timely detection of the problem and local paint or purge will save the threshold from through corrosion.
The myth of the "eternal" anticorea
It is believed that modern nano-components protect the car forever. That's a misconception. Any material is subject to aging under the influence of ultraviolet light (if it is outside), vibrations, temperature changes and chemistry. Even the most expensive processing requires monitoring and possibly partial recovery in 3-5 years.
The main secret of the durability of the thresholds is not so much the brand of anticores, as the quality of surface preparation and the regularity of monitoring the state of hidden cavities.
FAQ: Frequently Asked Questions
Can I put a new anticorer on top of the old one?
Yes, but with conditions. If the old layer is held tight, has not swelled and has not turned into debris, it can not be removed completely. The surface must be degreased and applied chemically compatible material. Oil compounds can be applied to almost any old anticores, as they have high penetrating ability and adhesion.
Do I need to drill additional holes for processing?
In most cases, modern cars already provide technological holes for factory and service processing. Drilling the body without extreme necessity is not worth it, as it violates the factory anti-corrosion protection around the hole and can lead to moisture in areas not intended for this purpose. Use available accesses or remove the skin/plastic to access.
What temperature does the anticores withstand inside the threshold?
High-quality anti-corrosion compounds for hidden cavities are designed for a wide temperature range, usually from -50 ° C to +100 ° C and above. Inside the threshold, protected from direct sunlight, the temperature rarely exceeds 60-70 ° C, even in summer, so the heat resistance of modern compounds is more than sufficient. Problems can only occur when welding near the treated area.
Is the smell of anticory in the cabin harmful after processing?
Immediately after treatment, the smell may be present, especially if solvent or oil-based formulations were used. It usually wears out within a few days with active ventilation. The use of water-based formulations or modern synthetic materials minimizes this effect. If the smell persists for a long time, it is possible that the composition was applied excessively or fell on the elements of the cabin.