High-quality painting of the car is not only the ability to hold the spray gun, but also competent preparation of materials. Many beginners make the fatal mistake of believing that it is enough just to open the jar and pour the contents into the sprayer. In practice, the consistency of the material should be strictly defined, otherwise defects will inevitably appear on the surface: shaven, subductions or “orange peel”. Proper dilution of paint is the foundation on which the entire paint layer is kept.
The process of mixing components requires precision and understanding of the chemical processes that occur when enamel is dry. Viscosity A key parameter that determines how the material will lie down, how quickly it will spread and dry. Too thick mixture will not have time to spread, leaving roughness, and excessively liquid will lead to the formation of flows and loss of color saturation. In this article, we will discuss in detail how to achieve the perfect consistency for different types of car enamels.
To work, you will need not only the components themselves, but also accurate measurement tools. Viscosimeter (Ford-4) will be your main assistant in determining the readiness of the mixture. Without it, all recommendations on proportions remain only approximate guidelines, since air temperature and humidity in the workshop can significantly affect the behavior of the solvent. Let’s look at the main stages of preparation for mixing.
Selection of components and preparation of the workplace
Before mixing, make sure that all components are compatible with each other. The chemistry of paintwork materials does not tolerate experiments "by eye". The main components for most modern systems are the base, hardener (for two-component materials) and solvent. It is important to use single-producer products or proven compatible counterparts to avoid swelling or changing the hue.
Particular attention should be paid to the choice solventIt is the one that regulates drying time and fluidity. Depending on the ambient temperature, fast, medium or slow solvents are chosen. If the garage is cold, a quick evaporator can lead to clouding of the varnish (the “whitening” effect), and in the heat, a slow one will not allow the paint to grasp, causing stains.
⚠️ Note: Never mix components of different chemical groups (e.g., nitro-emal with acrylic hardener) without proof of compatibility in the technical map. This can lead to irreversible damage to the material and damage to the coating.
Workplace preparation also plays a critical role. Dust that gets into the mixture when stirring will spoil the whole result. Therefore, the mixing zone should be kept clean, and all tools - measuring glasses, sticks, filters - should be perfectly dry and fat-free. Even a drop of water or oil can cause surface defects known as “craters” or “fish eye.”
Use only clean, dry measuring containers. Residues of an old solvent or water can react with the new material, changing its properties.
Mixing proportions for different types of enamels
Each type of car paint has its own unique requirements for mixing proportions. There is no universal recipe for everything, and blindly following the general rules can lead to marriage. Let’s look at the main types of materials that auto painters face.
For ecrylic (2K), which are most popular in body repair, is characterized by the addition of a hardener. The standard ratio is often a 4:1 scheme (four parts paint per part hardener), however, manufacturers may specify ratios 2:1 or 3:1. The solvent is added to a volume of 5-10% of the total mass of the mixture, but the exact percentage depends on the required viscosity and drying conditions.
Basic enamels (metallic, mother of pearl) are mixed differently. They are one-component in terms of polymerization reaction, but require dilution with a special solvent for bases. Here, the proportions are usually 2:1 or 1:1 (two parts base per solvent), but the final viscosity is dictated by the process map. lacqueThe stain, which is applied on top of the base, is also two-component and mixed with a hardener in ratios of 2:1 or 4:1, plus 5-10% solvent.
| Type of material | Proportion (Basic: Hardener) | Addition of solvent | The lifetime of the mixture |
|---|---|---|---|
| Acrylic enamel (2K) | 4 : 1 | 5-10% | 2-3 hours |
| Lacquer (2K) | 2 : 1 | 5-10% | 1-2 hours |
| Basic enamel (Metallic) | Not required | 50-100% (1:1 or 2:1) | Up to 6:00. |
| Sound filler | 4 : 1 | 10-20% | 1-2 hours |
Always check the instructions on the can of a particular product, as the chemical composition of pigments and resins in different brands may differ. A misdose of more than 5-10% of the hardener can cause the coating to either not dry or become too brittle.
Technology of preparation of mixture and mixing
The mixing process must take place in strict sequence to ensure uniformity of composition. First, the base (paint) is poured into the measuring glass. If the jar stood for a long time, the pigment could settle to the bottom, so before the tide it should be carefully stirred in the original container. Then the hardener is added in strict accordance with the chosen proportion.
After adding the hardener, the mixture must be intensively mixed with a clean wooden or plastic stick. The movements should be circular, with the capture of the bottom and walls of the glass to lift all the components. Do not shake the mixture like a cocktail, creating foam - air bubbles will make it difficult for the spray gun to work and leave craters on the surface.
Only after mixing the base and hardener (if any) is the solvent added. Its amount is adjusted depending on the indications of the viscometer. Viscosity is checked as follows: the mixture is scooped into the funnel, the hole is opened, and the time of complete leakage of the jet is recorded. For most spray guns, the optimal time is 18-22 seconds at a temperature of 20°C.
⚠️ Note: The “life” of the finished mixture is limited. After adding the hardener, an irreversible chemical reaction begins. If you do not use the paint for 2-3 hours (depending on the material), it will thicken and become unusable, even if you add another solvent.
To ensure the perfect result, the finished mixture must be filtered through a special funnel with a mesh (usually 125-190 microns). This will remove lumps, dust and skin particles that may have entered the glass. Neglect of filtering is one of the main reasons for the appearance of garbage on fresh painting.
☑️ Checklist for mixture preparation
Adjusting viscosity and working with a viscometer
Many masters neglect the use of a viscometer, relying on experience and visual assessment of the “drip from a stick”. However, this approach is fraught with mistakes, especially when changing seasons or the brand of paint. Viscosimeter It is a simple tool that gives an accurate numerical value of fluidity, allowing you to reproduce the result from time to time.
The measurement process is simple: fill the funnel to the brim, lift it and turn on the stopwatch at the moment when the jet begins to interrupt. For standard HVLP spray guns with a duse of 1.3-1.4 mm, the viscosity of 18-22 seconds is considered optimal. If the leakage time is less (for example, 12 seconds), the paint is too liquid - a high risk of stains. If more than 25 seconds - too thick, which will lead to shaking and poor bottling.
Adjustment of viscosity is carried out by adding a solvent in small portions. Added 5-10 ml - again stirred and checked. Don’t try to guess the volume the first time. It is also worth considering that with an increase in temperature in the chamber, the viscosity drops, so in the heat the mixture can become thinner already in the process of work.
The ideal viscosity depends not only on the paint, but also on the diameter of the spray gun duse and the pressure at the entrance. Always check the manufacturer’s recommendations for paint and equipment.
Temperature and choice of solvent
The ambient temperature directly affects the rate of evaporation of the solvent. Depending on this parameter, solvents fall into three main categories: fast (summer), medium (standard) and slow (winter). Using the wrong type is a common cause of defects.
In a cold room (below +15°C), the quick solvent evaporates instantly, cooling the surface of the part. This causes moisture to condense from the air on wet paint, causing matteness or "whitening." In such cases, it is necessary to use slow-motion Or raise the temperature in the paint chamber.
In hot weather (above 25°C), the slow solvent will not have time to evaporate, which will lead to long drying, stickiness and the risk of dust settling on a sticky layer. Here, on the contrary, a fast evaporator is preferred, which will provide a quick "grabbing" of the material.
It is also worth considering the temperature of the part itself. If you paint a cold car brought from the street, the paint on it will dry differently than on the metal heated in the chamber. Ideally, the temperature of the part, air and paint should be the same (about 20 ° C).
What to do if the paint is white?
If a whitish coating (whitening) appeared on fresh varnish or paint, this means that moisture was preserved in the layer. Sometimes it helps to add a special retarder (retarder) and re-application of a thin layer, but in severe cases grinding and repainting are required.
Frequent mistakes in the dilution of paint
Even experienced craftsmen sometimes make mistakes that negate all work. One of the most common is the use of a “left” or old solvent. The solvent is hygroscopic, it absorbs moisture from the air. If the solvent jar was open or leaky closed for a long time, water could accumulate in it, which will spoil the entire knead.
Another mistake is saving on filtering. A mottled mottling may require local polishing or even repainting of the element. It is also common to ignore the exposure time after mixing. Some materials need to stand for 5-10 minutes to get out of the mixture air bubbles and start the initial chemical reaction.
⚠️ Warning: Do not attempt to reanimate thickened paint that has already added a hardener by adding a large amount of solvent. This will break the molecular bonds, and the coating will lose its protective properties, becoming matte and unstable.
Ignoring the instructions on the bank is the way to marriage. Phrases like “always been in the way” don’t work with modern chemistry. Every new brand or even a new batch of paint can have nuances. Always read. Technical Data Sheet (TDS) - technical passport of the product, where all the nuances of the work are prescribed.
FAQ: Frequently Asked Questions
Can I use acetone or Kalosha gasoline instead of car solvent?
It's not recommended. Acetone is too aggressive and can “lift” the old coating or cause varnish clouding. Gasoline contains oils and impurities that will not dry and will remain in the paint layer, causing defects and color changes in the future. Use only specialized solvents (646, 650 or branded).
How long can you store the finished mixture with a hardener?
The lifespan of the mixture (pot life) is usually from 1 to 4 hours depending on the type of hardener and temperature. After that, the mixture begins to thicken and loses adhesion. You can not store the finished mixture “for tomorrow” – it will turn into a solid piece of plastic right in the jar.
Why does the paint fall in shaking, although viscosity on the viscometer is normal?
There may be several reasons: too long distance from the spray gun to the part, low pressure at the outlet, rapid evaporation of the solvent (heat) or insufficient surface temperature. Also, shaking can occur if the components are poorly stirred, and the viscosity in different layers of the glass differed.
Should I give the paint to stand after mixing?
Yes, most manufacturers recommend giving the mixed mixture stand for 5-10 minutes before pouring into the spray gun. This is necessary for degassing (the release of air bubbles) and the beginning of a chemical reaction between the components, which improves bottling.