How the varnish cracks on the car: diagnosis of causes and repair technology

Car owners often face an unpleasant situation when the glossy shine of the body is replaced by a network of small or large cracks. This phenomenon, known as craquelure or “spider web”, not only spoils the appearance of the body. motor-carIt also opens direct access to the aggressive environment to the metal parts of the body. Ignoring the problem in the early stages can lead to corrosion, the elimination of which will require a much larger financial investment.

The process of destruction of the lacquer layer can occur rapidly or develop over years, depending on the operating conditions and quality of the raw materials. Understanding the physicochemical processes that cause coating deformation is key to successful recovery. In this article, we will discuss in detail the mechanisms of defects and proven methods for their elimination.

The mechanism of crack formation and the physics of the process

To effectively combat the problem, you need to understand what is happening at the molecular level. Lacquer is a polymer film that loses its elasticity over time. The main factor in aging is exposure to ultraviolet radiation, which breaks down long chains of polymers, making the coating stiff and brittle. When paintwork loses the ability to stretch and contract together with the body at temperature changes, there is a rupture.

Often the process begins with microscopic damage, invisible to the naked eye. Under the influence of moisture, which penetrates into the micropores, and chemical reagents from the roads, the structure of the lacquer weakens. In winter, the situation is aggravated: the water in the cracks freezes, expands and literally breaks the coating from the inside, increasing the area of damage.

⚠️ Attention: If you notice that the cracks have reached the metal, immediately start repairing. Contact of oxygen and moisture with the body will cause focal corrosion, which will spread under the paint layer, causing swelling.

It is important to distinguish between types of cracking. A small net, resembling a web, usually indicates the aging of the upper layer. Deep cracks reaching the ground or metal, indicate more serious violations of painting technology or strong mechanical stress in the body. Two-component varnishes They are more resistant to such influences, but they are not eternal.

The main causes of defects in the coating

There are many factors that provoke the destruction of lacquer. Most often, it is not one cause that is to blame, but their complex effect. Experts identify several key aspects that must be considered when diagnosing.

• 🌞 Ultraviolet radiation: Long exposure to direct sunlight is the main enemy of polymers, causing their destruction and loss of plasticity.
• 🧪 Chemical reagents: Acid rain, bird droppings, tree sap and road salts aggressively affect the structure of the lacquer, corroding its surface.
• 🔧 Violation of painting technology: Incorrect surface preparation, incompatibility of materials or violation of the proportions of mixing components lead to internal stresses.
• 🌡️ Temperature extremes: The contrast between the sun-heated body and cold water during washing creates a thermal shock for the coating.

Particular attention should be paid to the quality of materials used in previous repairs. Cheap varnishes often don’t contain enough UV filters and plasticizers. Also, the cause can be the application of varnish on poorly dried paint or soil, which leads to locking solvents inside the layer.

Mechanical influences also play a role. The use of rigid brushes, abrasive polishes or improper washing technique (circular motions with effort) create microscopic structures that become centers of cracking onset. Ceramic coating It can protect the varnish, but only if it is applied correctly and regularly updated.

Diagnostics of the degree of body damage

Before starting repairs, it is necessary to accurately assess the scale of the disaster. From the depth of the cracks depends on the choice of recovery method. Surface diagnosis is performed visually in good lighting, but to accurately determine the depth of defects often requires an increase or special devices.

Use a magnifying glass or macro shot on your smartphone to consider the nature of the cracks. If only the top layer of varnish is damaged, deep polishing may help. If the cracks go deeper, polishing only temporarily hides the defect, filling the voids with polyrene, which will wash off after the first wash.

Type of damage	Depth.	Visual sign	Method of decision
Micro-scrambles	Surface layer	They are barely visible, only visible in the sun.	Abrasive polishing
Krakelyur (sweet)	Within the varnish	Grid of small cracks	Deep polishing or repainting
Deep cracks	To base or ground	Clear lines, visible contrast layer	Local or complete repainting
Bloating.	To metal.	Buggy with cracks on top	Cleaning to metal and painting

There is a simple test using a magnifying glass and a light source. Direct the light at a sharp angle to the surface. If the cracks disappear when applying a drop of water or polish, then the damage is superficial. If the relief and tears are visible even with the aggregate, serious intervention is required.

Repair technology: surface polishing

If the diagnosis showed that the cracks are not deep, you can try to save the situation with the help of abrasive polishing. The essence of the method is to remove the microscopic layer of varnish along with the damaged surface. For this purpose, special polishing pastes with varying degrees of abrasiveness are used.

The process requires accuracy and the presence of a special tool - a polishing machine. Start with a rougher abrasive, gradually moving to the finish polishing to restore the gloss. It is important not to overheat the surface, because heat-up It may cause it to become stained or to become more stained.

After removal of the main defect, the surface must be treated with protective compositions. It can be a wax, synthetic sealant or glass-glass. They fill the residual micropores and create a barrier to external influences. However, remember that polishing thins the layer of varnish, and it is often impossible to carry out it.

⚠️ Attention: Never do a dirty polishing on a dirty car. Dust, caught under the polishing circle, will work like sandpaper and leave deep scratches that will be extremely difficult to remove.

Radical measures: repainting of damaged elements

When the cracks are deep and affect the base layer of paint or soil, polishing is powerless. In this case, the only effective solution is to repaint the element. This process requires professional equipment, a paint camera and painter skills.

The first step is to clean up the damaged area. The old coating is removed to metal or to a strong layer of soil. The surface is grinded, degreased and ground. The quality of the surface preparation determines 80% of the success of the final result. Any defects left will show up after painting.

The Secret to the Perfect Transition

When local painting masters use the technique of "transition", shaking new paint on the border with the old. This allows you to avoid the visible border (step) and make the repair invisible to the eye.

Applying new layers of paint and varnish is made in several stages with observance of time intervals for drying. Modern varnishes often require forced drying in a chamber at a certain temperature for complete polymerization. After drying, the surface is polished to remove possible shaking and dust.

Prevention and care of paint coating

To the question of “how the varnish on the car cracks” does not arise before you too often, it is necessary to ensure proper care. Regular washing using high-quality autochemistry helps remove aggressive substances before they begin to break down the coating. Do not skimp on shampoos, as household chemicals can be too alkaline.

The use of protective coatings significantly prolongs the life of the varnish. Wax coatings require renewal every 1-2 months, while synthetic polymers and ceramics last from a year to several years. They create an extra sacrificial layer that takes the hit.

• 🚿 Regular washing: Removes salt, bitumen and bird droppings, preventing chemical corrosion of the lacquer.
• 🛡️ Protective compositions: The use of ceramic coatings or dense waxes creates a physical barrier.
• 🅿️ Right parking: Try to park in the shade or garage to minimize exposure to UV light.
• 🧽 Careful wash: Use the two-bucket method and soft microfiber mittens to avoid scratching the surface.

It is also important to remove bird droppings and traces of insects from the body in a timely manner. Their acids are able to burn the varnish in a matter of hours in hot weather. If you can not wash the car immediately, use wet wipes for express cleaning or special spray removers.

Frequently Asked Questions (FAQ)

Can I paint the cracks with varnish without a full repainting?

Local application of varnish is possible only if the cracks are very small and do not affect the colored layer. However, often the boundary between the old and new varnish remains noticeable (the effect of the "apple"), so the masters recommend repainting the element as a whole.

How much does it cost to restore the varnish in the service?

The price depends on the area of damage and method. Polishing can cost from 3 to 10 thousand rubles, while repainting one part in good service will cost from 15 to 40 thousand rubles and higher, depending on the class of cars and materials.

Will polishing help if the cracks feel like a nail?

If the nail clings to a crack, then the damage is deep. Polishing at best temporarily masks the defect, but after a couple of sinks it will appear again. In this case, a repainting is required.

Why does the lacquer crack on new cars?

On new cars, this is often due to factory defects (breaking drying or mixing technology) or improper storage prior to sale. Also, the reason may be the early use of aggressive chemistry or abrasive polishing by inexperienced washers.