When buying a used car or discussing its condition in a service center, you have probably come across the abbreviation LKP. For an experienced driver, this is a common abbreviation, but for a beginner it may not be clear. paintwork stands for paint coating, and it is this that is the first protective barrier of the car body from the aggressive external environment.
The condition of this layer directly affects not only the aesthetic appeal of the vehicle, but also its durability. Rust, chips and scratches are not just cosmetic defects, but areas of metal destruction that can lead to expensive repairs. Understanding the coverage structure helps you properly care for your car and not overpay for unnecessary services.
In this article, we will look in detail at what modern factory paint consists of, how to identify hidden defects using simple tools, and what restoration methods exist. You'll learn to read a thickness gauge like a pro and know when polishing is truly needed and when a piece needs a major repaint.
Structure and composition of modern paint and varnish coating
Many drivers mistakenly believe that paintwork is simply one layer of colored paint applied to metal. In fact, this is a complex multi-layer system developed by engineers to provide maximum body protection from corrosion, ultraviolet radiation and mechanical damage. Each layer performs its own unique function, and violation of the application technology of at least one of them reduces the resource of the entire coating as a whole.
The first and most important layer is phosphate layer, which is applied directly to degreased metal. It ensures adhesion (adhesion) of subsequent materials to the body and creates primary anti-corrosion protection. Without high-quality phosphating, even the most expensive paint will begin to peel off or let moisture into the metal after just a few years of use.
⚠️ Attention: If, when examining the edges of the doors or hood, you see swelling of the paint, this often indicates a violation of the technology for applying the phosphate layer at the factory or moisture getting under the ground due to a chip.
Next comes the layer soil (primer), which levels the surface and gives additional strength. It is the soil that takes the brunt of the impacts of small stones and sand. A base layer containing pigment and metallic, which is responsible for the color, is applied on top of the primer. The design is completed by a layer varnish, adding shine and protecting the color layer from fading and chemical reagents.
Depending on the type of paint (metallic, mother-of-pearl, acrylic), the number of layers of varnish and their thickness may vary. For example, in pearlescent paints, an additional intermediate layer can be applied between the base and varnish to create the effect of color depth. Understanding this structure is critical when assessing the quality of a paint job.
Why is factory paint stronger than repair paint?
Factory paintwork is applied under sterile conveyor conditions using robotic lines and high-temperature polymerization (about 200°C). Repair painting in services is carried out at lower temperatures (60-80°C) and in less controlled conditions, which makes the layer less hard and more susceptible to chipping.
Why do you need to check the thickness of the paintwork before purchasing?
Checking the thickness of the paint coating is a mandatory step in diagnosing a car before purchasing it. Even if the car looks perfectly clean and shiny, a (device) called a thickness gauge can tell a lot more about the vehicle's past than what the seller can say. The main purpose of such a check is to identify painted elements and putty.
Normal factory paint thickness for most modern vehicles ranges from 80 to 140 microns (µm). The values may vary slightly depending on the car brand and the specific body element. For example, the layer on the roof may be thinner than on the pillars or sills. Any significant upward deviation from the norm indicates the presence of an additional layer of paint or putties.
If the device shows values above 200-300 microns, this is almost guaranteed to mean that the element has been repainted. Readings of 1000 microns or higher indicate the presence of a layer of putty, which indicates serious repairs after an impact or accident. Buying a car with such defects without carefully checking the body geometry can be a big financial mistake.
In addition, the check helps to detect so-called “doubles” - cars that have been in serious accidents, but have been properly restored for sale. Different paint thicknesses on symmetrical elements (for example, the left and right wing) are the first sign that one of the sides has been renovated. Without the use of specialized equipment, it is almost impossible to notice the difference in shade or texture.
How to use a thickness gauge: instructions and explanation
Using a thickness gauge is a simple process, but it requires care and understanding of the operating principles of the device. There are magnetic and vortex sensors that react to the distance between the metal of the body and the probe of the device. The thicker the paint layer, the greater this distance. To obtain reliable data, it is necessary to follow a certain measurement methodology.
Before starting the test, the device must be calibrated. This is usually done using a reference plate or a clean section of metal (although it is difficult to find clean metal on a car, so factory values or calibration films are often used). Measurements should be taken at several points on each element: in the center, along the edges and at the folds, where the paint layer is usually thinner.
Here are the main ranges of values that you can see on the device screen:
- 🟢 90–140 µm: Factory finish in excellent condition.
- 🟡 150–200 µm: A second coat of paint or light polishing with abrasive compounds is likely.
- 🟠 200–500 µm: The item has been repainted and may have a thin layer of putty.
- 🔴 500+ microns: Thick layer of putty, serious body repair.
- ⚫ 0 µm or error: Plastic element (bumper, moldings) or sensor does not fit.
The thickness gauge on them may show zero or give an error, which is normal. To check plastic, special ultrasonic thickness gauges are used, but they are less common.
Wipe the body surface with a dry cloth before each measurement. Dust, dirt or moisture can distort the meter's readings, adding extra microns to the result.
Typical paintwork defects and reasons for their occurrence
Even with careful use, the car’s paintwork is constantly exposed to negative factors. Understanding the nature of defects helps to choose the right method for eliminating them and preventing further destruction of the layer. Some problems can be solved by polishing, others require local repairs.
One of the most common defects is holograms and circular risks. They appear after poor-quality washing or polishing, when solid dirt particles remain on the polishing wheel. Visually, it looks like rainbow stains, which are especially noticeable in the sun or under the bright light of lanterns.
Another common problem is chips and deep scratches down to the metal. They arise from stones and gravel flying off from under the wheels. If such a defect is not painted over in a timely manner by a restorer, the moisture will begin to oxidize the metal, and a “saffron cap” will appear under the paint, which will quickly grow. There is also corrosion that starts from the inside out, which is often a sign of defective initial painting or poor anti-corrosion treatment.
| Defect type | Reason for appearance | Elimination method | Difficulty |
|---|---|---|---|
| Piles (small risks) | Incorrect washing, dirty sponges | Abrasive polishing | Low |
| Oxidation (haze) | Ultraviolet, chemical reagents | Restorative polishing + wax | Average |
| Corrosion (saffron milk caps) | Chips, violation of paintwork integrity | Cleaning, priming, painting | High |
| Orange peel | Violation of painting technology | Deep polishing or repainting | High |
Separately, it is worth mentioning bitumen stains and traces of tree buds or bird droppings. Bitumen is easily removed with special cleaners that dissolve oil fractions without damaging the varnish. But bird droppings, if not washed off for a long time, can literally “burn through” the varnish and get to the base layer of paint due to the acid it contains.
⚠️ Caution: Never try to wipe off dried bird droppings or glue with a dry cloth. You are guaranteed to leave deep scratches on the varnish that will have to be removed by polishing.
Body restoration and care methods
Caring for paintwork is divided into two main areas: regular maintenance and restoration work. Regular care includes proper washing, the use of protective compounds (waxes, ceramic coatings, liquid glass) and timely removal of contaminants. This allows you to extend the life of the factory coating for many years.
Restoration work requires a professional approach. Polishing It can be abrasive (removes a micron layer of varnish to remove scratches) and protective (applying polishes). Deep abrasive polishing should not be carried out more than once a year, since the varnish layer is not endless. Excessive zeal can lead to the fact that the varnish is rubbed down to paint or even to the primer.
Ceramic coatings are becoming increasingly popular for car body protection. They create a hard glass-like layer on the surface that has hydrophobic properties (water rolls into balls) and better resists chemical reagents. However, “ceramics” does not protect against strong impacts from stones; for this, there are polyurethane films that are glued over paintwork.
☑️ Basic care for paintwork
At home, you can perform a light polish with soft products (“one-step polish”), which refreshes the color and removes fine cobwebs. To do this, use a polishing machine (or a drill with an attachment) and a foam polishing pad. The main rule is not to overheat the surface by working at low speeds and constantly moving the tool.
Regular application of protective wax after every third or fourth wash creates a barrier that absorbs the impact of reagents and dirt, keeping the base layer of varnish intact.
Legal aspects and impact on the cost of the car
The condition of the paintwork is one of the key factors influencing the market value of a car. A car with its original, albeit not perfect, coating is always valued higher than a repainted copy, even if the painting is done well. Buyers are afraid that repainting hides problems with body geometry or the consequences of a serious accident.
When selling a car, it is important to honestly inform the buyer about the repairs made. Concealing the fact of repainting may be grounds for termination of the transaction or a demand for a price reduction in court, especially if it is proven that the defects affected safety or cost. An expert opinion on the state of paintwork can serve as a powerful argument in disputes.
It is also worth considering that poor-quality paintwork repairs can lead to problems during technical inspection if corrosion reaches critical structural elements. Therefore, saving on body repairs “just so as not to rust” often backfires on the owner in the long run.
Is it possible to completely remove a scratch by polishing?
This depends on the depth of the damage. If the scratch does not touch the paint layer and is only in the varnish, then professional polishing can remove it completely. If the nail, when drawn across the scratch, “catches” on its edges, it means that the color layer is damaged. In this case, polishing will only mask the defect, making it less noticeable, but will not completely remove it.
Why does the paint peel off on some cars and not on others?
This depends on the quality of the factory process, in particular metal preparation and drying. Budget brands sometimes use less durable varnishes or skimp on anti-corrosion treatment. The environment also has an impact: in coastal regions with salty air or in cities where roads are abundantly watered with reagents, paintwork deteriorates faster.
Is it worth buying a polishing machine for your home?
If you plan to take care of one or two cars once a year, it is cheaper and safer to contact a detailing center. Buying a machine, circles and chemicals will only pay off with regular use. In addition, it is easy for an inexperienced user to rub off the varnish on the body ribs, which will lead to an expensive repaint.
How often should the car body be polished?
It is recommended to do abrasive polishing with removal of the varnish layer no more than once a year, and preferably once every 2-3 years, as defects appear. Protective polishing (with wax or liquid glass) can be carried out more often - every 3-6 months, depending on the composition used and the operating conditions of the car.