Wrongly selected solvent for acrylic enamel or base layer instantly leads to shaking, blurring of the varnish or long drying, making the result of painting defective. Unlike household paints, automotive materials require a strict chemical match between the main component, hardener and dilution fluid, since the disruption of this ligament changes the evaporation rate and surface tension. An error in choosing a solvent type at high humidity or low temperature in a paint chamber is guaranteed to cause the formation of craters or milk plaque (the “whitening” effect), which cannot be removed by polishing.
Main objective thinner It is not just to reduce the viscosity, but to ensure the correct spreading of the material on the surface of the body until the moment of polymerization. If you use too "fast" composition in hot weather, the paint will not have time to spread, leaving risks from spray gun, and "slow" in the cold will provoke leaks and a long drying time, which will increase the risk of dust adhesion. Professional painters always select the chemical formula for specific environmental conditions, strictly following the manufacturer's recommendations. paint-coating (LKP).
Chemical composition and classification of solvents
Automotive chemistry is divided into several classes depending on the rate of evaporation and chemical activity. Standard. white-spirit This is not a good option because it is too inert for modern two-component systems. The basis of professional diluents are esters, ketones and aromatic hydrocarbons, which provide the necessary aggressiveness for dissolving resins, but evaporate at a predictable rate.
- 🧪 Fast solvents (Rapid) - contain a high proportion of acetone or methyl ethyl ketone, are designed to work at low temperatures (up to +15 ° C) or to create thin layers.
- 🌡️ Normal solvents Normal is a universal formulation for standard conditions (+20°C) that provides a balance between spreading and drying speed.
- 🐢 Slow solvents (Slow) - enriched with heavy fractions for work in heat (above +25 ° C) or when applying large areas, preventing the paint from boiling.
It is important to distinguish between active and passive solvents. Active chemically interact with the film forming agent, completely dissolving it, while passive only dilute the mixture without reacting. Using a passive diluent for paint that requires active paint will result in material curling up in the jar or uneven drying on parts.
⚠️ Attention: Never mix solvents from different manufacturers and brands in the same container. Chemical additives and stabilizers can react in an unpredictable way, resulting in precipitation or a change in pigment color.
Chemical compatibility
The compatibility table shows that solvents based on esters (e.g. ethyl acetate) work well with acrylic enamel, but may be too aggressive for some types of plastic without a special soil-insulator.
Temperature regimes and selection of evaporation rate
The key success factor is matching the evaporation rate solvent the temperature of the air in the working area. If the chamber is +25°C and you use a compound for +15°C, the top layer of paint will dry instantly, sealing the solvent vapors inside. This will cause a “boiling” effect or the appearance of bubbles that will appear minutes or even hours after application.
When working in a cold room (below +18°C) the use of a slow diluent will cause the paint to remain liquid for too long. Gravity will cause the material to flow downwards, forming characteristic “tears” and swirls on vertical surfaces. In addition, a long drying time increases the “window” for settling dust and pile on fresh varnish.
There is also the term “metal temperature”. A piece that has just been removed from the freezer or, conversely, heated in the sun, requires an individual approach. The cold metal condenses moisture from the air, which, in combination with a slowly drying solvent, gives the effect of matteness.
Mixing proportions and material viscosity
Accurate compliance with the proportions is not a recommendation, but a technical requirement for obtaining the coating properties declared by the manufacturer. The standard ratio for most acrylic enamels and soils is 2:1 (two parts paint on one part hardener) plus 10% thinner. However, for base coats, the proportion can be as high as 1:1 or even require more solvent to produce a grain.
| Type of material | Standard proportion | Recommended viscosity (DIN4) | Duse diameter (mm) |
|---|---|---|---|
| Acrylic enamel (2K) | 100% + 50% of ETF + 10% of DISCOURSE | 18-22 sec. | 1.3 - 1.4 |
| Base layer (Basecoat) | 100% + 50% Distribution | 16-18 seconds | 1.3 - 1.4 |
| Acrylic varnish (Clear) | 100% + 50% of OTC + 5-10% of SOLUTION | 20-24 seconds | 1.3 - 1.5 |
| Sound filler | 100% + 25% of ETF + 10-15% of DISCOURSE | 25-30 sec. | 1.6 - 1.8 |
Viscosity measurement is performed using a viscometer (DIN4 funnel). If the paint flows too quickly, it will give stains; if it is slow, it will lie down with an orange peel. Always measure at a material temperature of +20°C, as cold liquid is always thicker.
☑️ Mixing readiness check
Do not try to save money by pouring solvent "on the eye". Overconsumption of material due to improperly prepared mixture will cost more than buying a measuring glass. In addition, the excess solvent reduces cover, causing you to apply additional, extra layers.
Application technique and work with the spray gun
Properly diluted paint should lie flat, glossy layer immediately after the passage of the torch. If you see that the material lies dry, rough, and the torch is sprayed with jerks, then the mixture is too thick or the air pressure is not high enough. In this case, you can add 5%. solventIt is best to check the pressure on the compressor first.
When applying the base layer (metallic), it is important not to overdo the amount of solvent. Excess liquid will cause aluminum powder or mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of mother of father of father of father of mother of father of father of father of father of father of father of father of father of father of father of mother of mother of mother of father of father of father of father of father of father of father of father of father of father of father of father. The first layer of the base is applied drier, the subsequent - more wet, but without the formation of gloss until completely drying.
⚠️ Attention: If after applying the varnish appeared microbubbles, in any case do not try to immediately wipe or blow them. Allow the coating to dry completely (at least 24 hours), otherwise you will only aggravate the defect by introducing the dust deeper.
Use a “tack cloth” before each layer of varnish or base to remove the settled dust and static electricity that attracts the villi.
Typical defects and ways to eliminate them
One of the common problems is the “orange peel” (shagrin). It arises when solvent It disappears too quickly, and the paint does not have time to spread. This is treated by polishing if the defect is superficial, or repainting using a slower solvent and proper drying between the layers.
Another common defect is “boiling” or foaming. This is a direct consequence of using a quick solvent on a hot part or in a hot room. Bubbles burst, leaving craters. This can be eliminated only by complete removal of the coating, grinding and repainting in compliance with the temperature regime.
- 💧 Moisture poisoning - turbidity of the varnish (blush coating) occurs at high humidity and the use of a quick solvent, which cools the surface, condensing water from the air.
- 🌫️ Matness Often occurs when applying varnish to an undried base layer or when using a dirty, poor-quality diluent.
- 🎨 Ratio If the solvent is not selected correctly, the pigment may lie differently, and the color will no longer match the original, especially on metallic materials.
Abrasive treatment is required to eliminate most defects. The fine shavern is removed by polishing pastes of different abrasiveness, starting with the P1500-P2000. Deep craters or streams require ground sweep and local paint.
Security measures and storage of materials
Vapors of automotive solvents are toxic and flammable. The main danger is not so much short-term inhalation, but the cumulative effect and risk of vapor explosion in a confined space. Working without a respirator with organic solvent prohibited, as they affect the central nervous system and blood-forming organs.
Chemicals must be stored in tightly closed containers, away from sources of fire and direct sunlight. The optimal storage temperature is from +5 ° C to +25 ° C. If the jar with solvent is frozen, it can be carefully warmed at room temperature, but it is strictly impossible to use open fire or heating devices.
Saving on a quality solvent and protective equipment is a direct way to marriage in painting and health problems. Cheap analogues often contain impurities that destroy paint.
Can acetone be used instead of a special solvent?
Use of pure acetone instead of a specialized automotive diluent is highly recommended. Acetone has a very high evaporation rate and aggressiveness. It can instantly “burn” the bottom layer of paint, cause turbidity of the varnish or change the shade of the pigment. In emergency cases (for example, wash the tool), it can be used, but for the preparation of the working mixture - not.
What to do if the paint is curled up in a jar?
If the paint curled up when mixed (flakes or lumps), then there was a chemical incompatibility of the components. Most often, this is a reaction of a hardener with a solvent containing alcohols, or mixing materials on different bases (for example, nitro with acrylic). It is impossible to save such a mixture, it will have to be disposed of, and the tool is thoroughly washed.
How long does the paint with solvent dry?
The drying time depends on the type of solvent and temperature. “Fast” dries to a stick in 15-20 minutes at +20 ° C, “normal” – for 30-40 minutes, “slow” – up to an hour or more. Full polymerization (hardness set) takes from 24 hours to several days. Lacquer with slow solvent can stay soft longer, but gives better bottling.
Do I need to filter the diluted paint?
Yes, filtration is mandatory. Even in new banks, clots can come across, and in the process of stirring, garbage can get into the mixture. Use special paint funnels with a built-in filter (usually 125-190 microns). This will save the duo of the spray gun from clogging and ensure smoothness of the coating.