Getting a perfectly smooth surface of the body, devoid of defects, is a top aerobatics for any painter. Shagrin, or “orange peel”, often becomes an uninvited guest, spoiling the appearance of even a well-prepared car. Removing this defect requires not only expensive materials, but also a deep understanding of the physics of the drying process of paints.
In this article, we will discuss the key factors affecting the spread of enamel and varnish. You will learn how to set up equipment, prepare the room and mix the components correctly to achieve the effect of factory coating. Perfect result This is achieved only with strict control of all parameters at each stage of work.
Often beginners sin by blaming the quality of the paint, forgetting about the banal mistakes in setting up the spray gun. In fact, even the cheapest material can be stacked exactly if the technology is followed. Conversely, a premium product will turn into a bumpy mass if used incorrectly.
The nature of the occurrence of shashashare on the body
Shagrens are a surface irregularity, resembling the skin of citrus fruits. This defect occurs due to the fact that the liquid film of paint does not have time to spread into a smooth layer before polymerization. Viscosity of material This is crucial: if it is too high, the molecules cannot move fast enough to align.
There are several main reasons for the appearance of bumpiness. Often the problem lies in the wrong solvent, which evaporates too quickly, “freezing” the surface. Also affected by the temperature in the paint chamber and the speed of movement of the sprayer.
Use a solvent with slower evaporation in hot weather to give the paint more time to spread out.
It is important to understand the difference between a small shaveren that is polished and a large one that requires repainting. Small ripples are permissible within factory tolerances, while large bumps indicate a gross violation of application technology.
⚠️ Attention: Applying an excessively thick layer of varnish "at low tide" is almost guaranteed to lead to the appearance of large shaking and leaks.
Surface preparation and choice of materials
The foundation of quality coverage is impeccable preparation. Any dust, fat or unevenness of the soil will appear under the enamel layer. Before starting work, it is necessary to carefully degrease the surface and blow all the cracks with compressed air.
The choice of materials must meet the conditions in the color box. If you work in a cold room, using a quick solvent will lead to mattiness and shaking. In contrast, in heat, a slow solvent can cause slugs.
Pay special attention to filtering the mixture. Even microscopic dust particles in the paint can disrupt the uniformity of the spread. Use quality funnels with a mesh and filters-capples on the spray gun.
- 🧪 Mix the paint and varnish components thoroughly to avoid heterogeneity of the composition.
- 🌡️ Allow the mixed material to stand for 10-15 minutes to release air bubbles.
- 🧹 Rub the surface with an antistatic wipe immediately before painting.
Do not skimp on solvents and hardeners. Cheap analogs can have an unstable formula, which will lead to unpredictable behavior of the material when drying. Certified products The well-known brands provide predictable results.
Setup of the spray gun for the perfect torch
The correct configuration of the spray gun is 80% of the success in the fight against shaveren. The pressure at the outlet of the head, the shape of the torch and the amount of material supply must be balanced. The standard pressure is usually 2.0-2.5 atmospheres, but it can vary.
The shape of the torch should be adjusted depending on the part being painted. For large planes, such as the hood or roof, the torch is opened as much as possible. For narrow elements, such as racks or rapids, the torch is narrowed to reduce material loss and fog formation.
The distance to the surface is also critical. The optimal distance is 15-20 cm. If you hold the gun closer, the layer will be too thick and stained; if further - the paint will dry in flight, lying dry dust.
⚠️ Attention: Sharp movements of the wrist when painting change the distance to the detail, which creates stripes of different thickness and provokes shaking.
Check the torch always carried out on the test surface or watman before starting work on the car. This will allow you to see the real spray and, if necessary, to twist the regulators.
Technology of application of the base layer and varnish
The painting process is divided into several stages: applying the base (colored layer) and coating with varnish. The base is applied in thin layers with mandatory interlayer drying. The task of the base is to give color and cover, but not a glossy surface.
The lacquer is applied in wet layers. This is where the gloss is formed. The first layer of lacquer is often made thin, "dusty", for better adhesion. The second and third layers are applied abundantly, achieving spreading.
☑️ Checklist before applying varnish
It is important to observe time intervals. If the next layer is applied too early, the solvent can boil inside, creating craters. If you overdo it, interlayer adhesion will be broken, and the varnish may peel off over time.
The movements of the gun must be smooth and parallel to the surface. The overlap of the strips should be 50-70%. This ensures a uniform distribution of the material and the absence of stripes.
Effects of temperature and humidity in the chamber
The climatic conditions in the paint chamber directly affect the rate of evaporation of the solvent. The optimum air temperature is 20-22 ° C. At lower temperatures, the viscosity of the paint increases, and it spreads worse.
The humidity of the air also plays a role. Too dry air accelerates evaporation, which can lead to dry shaking. Excessive humidity causes varnish clouding (white coating) and slows down drying.
The temperature of the car must be equal to the temperature in the chamber. If you paint a cold detail in a warm box, moisture will begin to condense on the surface, which will spoil the coating. Therefore, heating the body is mandatory.
| Parameter | Optimal value | Effect of deviation |
|---|---|---|
| Air temperature | 20–22°C | Cold: shaking; Heat: boiling |
| Humidity | 50–60% | High: cloudy; low: dry groove |
| Pressure in the spray gun. | 2.0-2.5 atm | Low: large shaft; High: fog |
| Spraying distance | 15–20 cm | Close: subtracts; far away: dry spraying |
How to warm up the body before painting?
Turn on the infrared lights or just leave the car in a warmed-up chamber for a few hours. The metal temperature should be stabilized.
Pollination and elimination of minor defects
Even with perfect painting, microscopic shavern may be present. Factory shavern is considered normal if it is not conspicuous. Abrasive polishing is used to achieve mirror shine.
The process begins with the surface grinding with a P2000 or P2500 abrasive. This allows you to cut the upper bumps of the shashaverin, making the surface flat. The main thing is not to wipe the polish to the base.
After grinding, the surface is polished with a machine using polishing pastes of different abrasiveness. First, use a rougher paste to remove risks, then the finish to give gloss.
- 🛠️ Use an orbital rotary machine to evenly remove the layer.
- 💧 Constantly wet the surface with water when grinding to avoid overheating.
- ✨ Finish polishing returns transparency and depth to color.
Don't overdo it with polish. The polish has a limited thickness, and frequent polishing thins it. Safe thickness The lacquer layer should be controlled by a thickness gauge.
The quality of polishing directly depends on the quality of pre-surfacing - the more uniformly the shaver is removed, the better the final gloss.
Common Mistakes and How to Avoid Them
Many of the masters step on the same rake. The most common mistake is the desire to paint “once” with a thick layer. This leads to inevitable undercurrents and major shaking that is difficult to remove.
Another mistake is to ignore the purity of the instrument. Dried particles of paint in the channels of the gun can fly out in the process of work and spoil the fresh layer. Regular washing and maintenance of the spray gun is mandatory.
Also often there is the wrong selection of solvent under temperature. Summer solvents in winter behave like water, and winter solvents evaporate instantly in summer, preventing the paint from spreading.
⚠️ Warning: Using dirty or humid compressed air from the compressor is guaranteed to spoil the coverage with craters and bubbles.
Avoid rushing. Quality painting takes time to prepare, mix and interlayer dry. Haste is the painter's main enemy.
Can I remove the shaver without polishing?
Completely remove the shaft without mechanical impact (polishing and polishing) is impossible. There are “antishagrens” in the form of additives, but they only slightly improve the spreading. Only abrasive can radically change the structure of the already dried lacquer.
How long after painting can you polish?
The time of complete polymerization of the varnish depends on the type of hardener and temperature. It is usually recommended to wait 3 to 7 days before polishing. If you start too early, the varnish will "float" under the typewriter and hammer the abrasive.
Which abrasive is best used to remove shaking?
The best choice is waterproof sandpaper of graduation P2000 or P2500. A rougher abrasive (P1000-P1500) will leave a deep risk that will be difficult to remove by polishing, and a smaller one will not effectively remove bumps.