Many car owners are faced with an unpleasant problem: small red dots appear on the shiny varnish, which over time grow and turn into through holes. This phenomenon is popularly called “bugs”, and it is nothing more than pockets of corrosion. Fighting bugs - This is not just a matter of aesthetics, but a necessary measure to preserve the integrity of the body and prevent costly repairs.
If you notice the first signs of rust, you need to act immediately. Ignoring the problem will lead to the fact that after a few months the entire part will need to be replaced rather than a local repair. In this article we will look at why corrosion occurs, how to properly prepare the surface, and what methods exist to eliminate defects.
Causes and types of corrosion
The main enemy of metal is the interaction of iron with oxygen and moisture. The oxidation process starts at the slightest damage to the paintwork (paintwork). Galvanic corrosion often occurs at points of contact between different metals, but most often we are dealing with atmospheric corrosion caused by reagents on the roads and high humidity.
There are several stages of development of “bugs”. At the initial stage, the rust is superficial and can be easily removed. If the process is started, the metal begins to exfoliate, forming deep shells. It is important to understand that hidden corrosion can develop under a layer of paint, swelling it from the inside.
Most often, outbreaks appear in areas where dirt and moisture accumulate: sills, wheel arches, bottom of doors and edge of the hood. It is these places that require increased attention during washing and inspection.
Diagnostics and assessment of the scope of work
Before you begin any active actions, you must carefully inspect the car. Often external manifestations are just the tip of the iceberg. For an accurate diagnosis, use a magnet wrapped in a thin cloth: in places of corrosion or putty, it will hold weaker or not at all.
Assess the depth of metal damage. If the rust has eaten right through the body, simply painting over it will not be enough - you will need to install patches or replace the entire element. Superficial lesions can be eliminated with your own hands at minimal cost.
Pay special attention to hidden cavities. If the “bugs” are visible from the outside, it means that the process inside may have been going on for a long time. Internal cavities are difficult to access for processing, so their condition often determines the outcome of the repair.
⚠️ Attention: If, when pressing on the source of corrosion, the metal is crushed or crumbles, then the structure of the metal is broken. In this case, simple painting is useless - serious body work is needed to cut out the rotten metal.
To assess the scope of work, you can use the table of common problem areas:
| Vehicle zone | Probability of occurrence | Typical reason | Difficulty of repair |
|---|---|---|---|
| Door edges | High | Mechanical chips, moisture | Average |
| Wheel arches | Very high | Sandblasting, reagents | High |
| Thresholds (bottom) | Critical | Accumulation of dirt, salt | Very high |
| Hood (front edge) | Average | Stones from the road | Low |
Required tools and materials
A high-quality result is impossible without the right tools. You will need not only paint, but also surface preparation products. The basis for success is thorough removal of rust to bare metal.
The list of required equipment includes both mechanical and chemical means. Do not skimp on consumables, as cheap materials can quickly become unusable or give poor results.
- 🛠️ Angle grinder (grinder) with petal circles or “brush” attachments to remove the bulk of rust.
- 🧪 Rust converter - a chemical composition that stops oxidation.
- 🎨 Primer-enamel and varnish to restore the protective layer.
- 🧽 Sandpaper of various grits (from P80 to P2000) and degreaser.
Which rust converter should you choose?
There are acid and neutral converters. Acidic ones (based on orthophosphoric acid) are more aggressive and remove oxides better, but require careful rinsing. Neutral (tannin-based) transform rust into a protective film and do not require rinsing, remaining under a layer of paint. Neutral formulations are better suited for beginners, as they forgive mistakes in technology.
Mechanical method of removing rust
The most reliable method is to completely remove the source of corrosion mechanically. This is a labor-intensive process that takes time, but guarantees long-lasting results. The essence of the method is to strip the damaged area down to “living” metal.
Start by cleaning the fireplace with a grinder and an abrasive wheel. Move from the edges of the damage to the center, gradually expanding the treatment area. It is important not to overheat the metal so that the body part does not move. After rough sanding, use sandpaper to smooth out the transitions.
If small spots remain after cleaning, you can use a chemical method, but the bulk of the rust must be physically removed. The surface should become smooth and matte.
After machining, be sure to blow all pores of the metal with compressed air to remove dust. Any dust left in microcracks can become a new source of corrosion.
☑️ Checklist for mechanical cleaning
Chemical processing and converters
In cases where mechanical cleaning is impossible or rust has penetrated into hard-to-reach places, chemicals come to the rescue. Rust converters react with iron oxide, turning it into a stable compound.
Before applying chemicals, the surface must be cleaned of dirt and oils. Apply the composition with a brush or spray, strictly following the instructions on the bottle. Typically, a certain amount of time is required for the reaction to occur.
Some compositions require rinsing off with water, others become a base under the soil. It is important not to overexpose acidic compounds so that they do not begin to corrode healthy metal. After treatment, the surface often darkens - this is a normal reaction.
Usage phosphoric acid - classic method. It creates a protective film that prevents the access of oxygen. However, if the acid is not neutralized after application, it may continue to work under the paint.
⚠️ Attention: Work with chemical converters only in a well-ventilated area and use personal protective equipment (gloves, respirator). Acid fumes can be toxic.
Restoration of paintwork
After the metal has been cleaned and treated with a converter, the stage of restoring its appearance begins. You cannot skip the priming step, as the paint does not adhere well to the metal and may bubble again.
Apply 2-3 coats of primer, allowing each layer to dry according to the instructions. The primer levels the surface and ensures adhesion (adhesion) of the paint. After drying, the primer is sanded with fine sandpaper (P800-P1000) until perfectly smooth.
Then the base paint is applied. Color selection is a critical point. Use your vehicle's color code located on the placard in the door frame or under the hood. The paint is applied in thin layers, avoiding smudges.
The final stage is applying varnish. It protects the paint from fading and mechanical stress. After complete polymerization (after a few days), the surface can be polished to remove shagreen and make the transition invisible.
The quality of the repair directly depends on the surface preparation. 90% of success is thorough cleaning and degreasing, and only 10% is the painting itself.
Preventing the reappearance of “bugs”
The fight against corrosion is an ongoing process. Even after high-quality repairs, there is no guarantee that rust will not return if preventive measures are not followed. Regular care extends the life of the body by years.
The first rule is frequent washing, especially in winter. Rinse off reagents and salt as quickly as possible. Pay special attention to the arches and bottom. Usage active foam Helps wash away dirt from hard-to-reach places.
The second rule is periodic treatment with wax or ceramics. Protective coatings create a barrier between paintwork and the environment. It is also recommended to treat hidden cavities with an anticorrosive agent once every 1-2 years (for example, Movilem).
- 🚿 Wash your car at least once every two weeks, and more often in winter.
- 🛡️ Apply protective wax to the body once every six months.
- 🔍 Inspect the chips regularly and immediately paint over them with a corrector pencil.
- 🅿️ Try not to park on wet grass or in damp garages without ventilation.
How often does the anti-corrosion coating need to be renewed?
Professional treatment of hidden cavities with anticorrosive agents lasts an average of 2-3 years. After this, it is recommended to diagnose the protection status. If you operate your car in harsh conditions (constant trips through wet snow, reagents, off-road), the inspection should be carried out annually. External coatings (wax, polymers) require renewal every 3-6 months, depending on the durability of the composition.
Is it possible to paint over rust without sanding?
Absolutely not. Painting over rust without removing oxides is a temporary measure that will give a visual effect from a couple of weeks to several months. The rust will continue to grow under the paint layer, and after a short time a new layer will swell. High-quality repairs require removing all sources of corrosion to bare metal.
What to do if rust appears under the plastic?
It is necessary to dismantle the plastic element (mudguard, threshold trim). Most likely, moisture and dirt accumulated underneath it, which caused corrosion. After removing the plastic, carry out a complete stripping, treatment with a converter and painting. Before installing the plastic back, treat the inside of the part with an anti-corrosion agent to prevent the situation from reoccurring.