Bloating of the paint coating, resembling small pimples, is the first visible sign that an active process of metal oxidation has begun under a thin layer of enamel. If you find such defects on the arches, sills or doors, you need to act immediately, as the focus of corrosion spreads deep and wide, destroying the structure of the body faster than it seems at first glance. Ignoring the “bugs” at an early stage leads to a through hole, the repair of which will require no longer cosmetic paint, but full-fledged metal digestion and expensive restoration in the service.
The main reason for the appearance of such defects is a violation of the integrity of the protective layer: chipped stones, scratches after washing or poorly carried out bodywork in the past. Moisture and reagents, which are treated roads in winter, penetrate through microcracks to the metal, triggering a chemical oxidation reaction. Corrosion under the paint grows cone-like: a small point on the outside can hide a vast cavity of rust, which literally “eats” the steel from the inside, peeling off the paint material.
Self-resolving of the problem is possible if the area of the lesion does not exceed reasonable limits and the metal has not yet turned into a sieve. You'll need a set of abrasives, a degreaser, to work. soil or a separate soil, as well as paint in the color of the body. It is important to understand that simply paint over the bloating from above is pointless – the rust will continue to live under a new layer, and after a couple of months the defect will appear again, so the technology requires the complete removal of the oxidized metal to the living surface.
Diagnostics and assessment of body damage
Before the start of active actions, it is necessary to soberly assess the scale of the disaster, since the choice of the method of recovery depends on this. Visual inspection is often deceptive: what looks like a small dot can be a deep crater when probed. Take a thin stitch or needle and gently press on and around the center of the bug. If the metal falls or crumbles under easy pressure, then the structural integrity of the panel is broken and will be required. reinforcement Replacement or even replacement of the element.
Particular attention should be paid to hidden cavities and welds, where moisture stagnates most often. Often, corrosion foci are hidden under rubber seals, moldings or at the bottom of doors. If you plan to deal with rust qualitatively, you will have to dismantle all the interfering elements to access the full picture of damage. Ignoring hidden foci will lead to the fact that the outer gloss quickly disappears under new bubbles protruding from under the paint.
⚠️ WARNING: If you hear a deaf sound or feel the metal vibrating with your finger or tool, it is a sign of the paint detaching from the rust over a large area. In such cases, the sweep must be radical, capturing healthy metal around the visible defect.
For accurate determination of the boundaries of the lesion, you can use a special magnet with a coating thickness indicator, although tactile testing is enough in everyday conditions. Healthy metal rings and holds the load, and the rust affected becomes soft and loose. diffuse corrosion It often has no clear boundaries, so you need to clean with a margin of 2-3 centimeters from the visible edge of swelling to ensure that all microscopic foci are removed.
- 🔍 Visual inspection in bright light helps to identify microscopic chips that will become future centers of corrosion.
- 🖐 Tactile finger check allows you to feel irregularities and bloating, invisible to the eye at an early stage.
- 📌 Piercing the needle center of the "bug" determines the depth of the lesion and the presence of a loose structure under the paint.
- 💧 Checking drainage holes in doors and sills is necessary, since the accumulated water is the main enemy of metal.
Required tools and materials for the job
The quality of the result directly depends on the materials and tools used, so their choice should be approached responsibly. Do not save on abrasives and chemistry, as cheap analogues can not give the desired adhesion or, worse, accelerate the process of destruction of metal. The basic set includes sandpaper of various grains (from P80 to P2000), a rust converter, degreaser and paint tape to protect neighboring elements.
To remove the main array of corrosion is convenient to use grinder with a petal circle or a nozzle "ersh" on the drill. However, in hard-to-reach places and with spot repairs, it is better to work manually so as not to damage entire sections of the body. You will also need a putty (if there are dents), soil (acid or epoxy), base and varnish. If the color of the car is complex (for example, mother of mother of mother of mother-of-pearl or three-component red), you will need an accurate selection of enamel in a specialized laboratory for the body code.
Use a flashlight with cold light to inspect the body: it better detects elevation differences and microscopic surface defects than the warm light of an incandescent lamp.
An important component is rust-converterIt converts iron oxides into stable compounds, stopping the process of destruction. There are compositions that can be left under the paint, and those that require mandatory washing. Carefully read the instructions on the bottle, as the chemical composition of different manufacturers can be radically different. Also, don’t forget about personal protective equipment: respirator, gloves and glasses, as dust from rust and a couple of solvents are harmful to health.
| Materials | Appointment | Features of application |
|---|---|---|
| Pearl P80-P120 | Rough sweep | Remove the main layer of rust and old paint |
| Converter | Chemical protection | Stops oxidation, takes time to react |
| Acid soil | Primary protection | It is applied in a thin layer only on metal, you can not hide. |
| Acrylic soil | Alignment | Creates a base for paint, fills the risks from sandpaper |
| Degreaser | Cleanup | Remove silicones and oils before each stage of painting |
Mechanical corrosion removal technology
The most time-consuming but critical step is the complete removal of the oxidized metal. You can not just clean the top of the “bug”, you need to get to the clean, shiny metal. Start by cleaning the damaged area with grain sandpaper P80 or P120. Movements must be confident, capture a healthy surface around the defect, forming a smooth transition (cutting edges), so that the boundaries of the repair are not visible later.
If the rust has penetrated deep and formed shells, mechanical cleaning may not be enough. In such cases, chemical agents or electrochemical methods are used (for example, the galvanic method with zinc), but the classical cleaning remains the most reliable. After removing the main layer of rust, the surface will become rough and matte - this is a normal condition for further priming. The main thing is that there are no red spots or spots.
☑️ Preparation for clean-up
When working with large areas, use a grinder, but control the heating of the metal. If the metal overheats, it can lead, which will create new problems with the geometry of the body. For point "bugs" are ideal special abrasive nozzles on a drill or drill, which allow you to work locally without touching the whole paint. After the mechanical cleaning is completed, thoroughly blow the surface with compressed air to blow dust out of the metal's micropores.
⚠️ Warning: Never leave the metal unprotected for long periods. In the air, fresh metal begins to oxidize in a matter of minutes, forming a thin layer of “rusty film”, which will worsen the soil adhesion. You need to be ground immediately after degreasing.
Chemical treatment and surface polishing
After the metal is cleaned, it is necessary to neutralize the residues of corrosion that could remain in the pores. This is what is used for. rust-converter. Apply it with a brush on the cleaned area and let it dry according to the instructions (usually 15 minutes to several hours). As a result of the reaction, the metal will turn black or be covered with a gray coating - this is a normal process of forming a protective film.
The next step is to apply the primary soil. For the body of the car is best suited acidicIt provides maximum adhesion and anticorrosion protection. It is applied in a thin layer (1-2 microns) and dries very quickly. Acid soil can not be grinded and it can not be applied to the usual putty (only polyester), so on top of it, after drying, usually apply a layer of acrylic soil-filler.
Acrylic soil serves to level the surface and fill the drawings from sandpaper. It is applied in 2-3 layers with interlayer drying. After complete drying (it is better to let dry for a day or speed up the process in the drying chamber), the soil is sanded with P400-P600 sandpaper for painting. The surface should become perfectly smooth, matte and homogeneous, without changes and pores.
- 🧪 The chemical converter penetrates into the micropores, where the sandpaper does not reach, stopping corrosion from the inside.
- 🌫 Acid soil creates a barrier to oxygen and moisture, working as a passivator of metal.
- 🎨 Acrylic filler allows you to level the relief and hide small scratches before painting.
- ⏳ Keeping the drying intervals between layers is critical to preventing defects.
Can I paint without soil?
Theoretically, there are paints “3 in 1” (surface paint), but their anticorrosion properties are much inferior to the classical scheme. For long-term repair of "bugs" the use of separate acid and acrylic soil is mandatory. Savings at this stage will result in the reappearance of rust after one season.
Painting and finishing of repaired site
The final stage is the application of paint coating. If you use an aerosol can, shake it thoroughly for 2-3 minutes. The paint is applied in 2-3 thin layers with interlayer drying (usually 10-15 minutes). The first layer may be semi-wet (foggy) to provide adhesion, the subsequent - more saturated, but without leaks. It is important to observe the temperature regime: optimally work at a temperature of +20 ° C.
After drying the base (enamel) is applied varnish. It protects the paint from ultraviolet light and mechanical influences. Lacquer is also applied in 2-3 layers. If the transition between new paint and old paint is too noticeable, it may be necessary to polish the transitions or even paint the entire part. For local repairs, the “back-to-back” method is often used, when the paint is applied only to the center of the defect with the edges being sturged, but this requires high skill.
After complete polymerization of the varnish (after a few days), the surface can be polished with abrasive paste to remove the "sharp" and make the transitions less noticeable. Polishing It also gives a deep shine and aligns the optical properties of the coating. If done correctly, the renovated site will last for years without requiring any intervention.
⚠️ Note: Do not attempt to accelerate drying with a hair dryer or fan heater immediately after applying the paint. Sharp heating can lead to boiling of the solvent, the formation of bubbles and varnish clouding. Dry naturally or in a specially equipped chamber.
Prevention of reappearance of rust
Even high-quality repairs do not guarantee eternal protection, if you do not follow preventive measures. Regular car washing, especially in winter and early spring, helps remove aggressive salts and reagents. Pay special attention to the arches and bottom: use high-pressure washers with caution so as not to damage the anticor, but thoroughly wash the dirt from the hidden cavities.
Once a year, it is recommended to inspect the body and, if necessary, update the wax coating or use special polishes with wax or silicone content. These compounds create a hydrophobic layer that repels water. It is also useful to periodically process chips and scratches with special pencils-correctors, without waiting for them to turn into “bugs”.
Compliance with the technology of washing (do not wash with hot water in the cold, dry dry dry the body) and car storage (garage is better than the street) significantly prolongs the life of the body. If the car is stored outside, use a high-quality case, but only on a dry body, otherwise a greenhouse effect will be created under the fabric, accelerating corrosion.
Do I need to make holes or will I have enough putty?
Putty is not a structural material and does not hold moisture. If a through hole has formed, the metal must be brewed (welded patch) or used fiberglass with resin for large areas. The putty on top of the hole will quickly crack and absorb moisture, which will lead to a repair dump.
Can I paint the bugs without stripping them to metal?
No, it's a temporary measure for a couple of weeks. The rust will continue to develop under the paint. The only way is a complete stripping to pure metal, processing with a converter and priming. Trying to “mask” the problem will result in more expensive repairs in the future.
Which rust converter is better to choose?
Well-proven compositions based on orthophosphoric acid with zinc or tannin. Zinc-containing transducers create an additional protective layer. It is important to choose those that form a strong film that can be ground, rather than those that require careful washing off with water (which can start corrosion again).
How much dried car paint?
The drying time depends on the type of paint and temperature. The base dries for 10-20 minutes per stick, but full polymerization takes 24 hours. The polish dries for about an hour before touch-dry, but it gains full hardness for several days. Full operation is possible in 24 hours, washing - in 7-14 days.