How to dilute paint for spray gun: proportions, solvents and viscosity

The quality of painting the car body directly depends on how well prepared the paint material. Many beginners make the mistake of trying to spray thick enamel from a jar, which leads to the formation of shavelins, undertacks and an uneven layer. Viscosity of paint This is the main parameter that determines whether the coating will lie flat or turn into an orange peel. The spray gun, regardless of its cost and spray system (HVLP, LVLP, RP), requires a certain fluidity of the material to form the perfect torch.

The process of dilution seems simple only at first glance, but this is where the secret of professional results lies. You need to consider not only the type of paint, but also the temperature in the paint chamber, as well as the diameter of the duse of your tool. Incorrectly selected solvent can spoil the whole result, causing blurring of the varnish or changing the shade of the base layer. In this article, we will discuss in detail how to achieve the perfect consistency using measuring cups and viscometers.

To begin with, it is important to understand that the factory consistency of paint in a jar is rarely suitable for immediate application through a spray gun. Manufacturers often make the material more thick for long-term storage. Therefore, your task is to bring the mixture to a working state, while maintaining all the covering properties. Dilution proportions They are always listed on the label, but they may need to be adjusted depending on the environmental conditions.

Choosing the Right Solvent and Its Role in the Process

The first thing you need to decide on before starting work is the type of solvent. It doesn’t have to be universal, but it has to be consistent with the chemical basis of your paint. Using an aggressive or too fast solvent can lead to instant dried paint still in the duse of the spray gun, which will cause it to clog. In contrast, too slow a solvent will increase drying time and increase the risk of dust getting to the fresh layer.

For automotive enamels, solvents based on esters, ketones or mixtures thereof are most often used. It is important to distinguish between active and passive diluents. Active participate in the chemical reaction and affect the structure of the film, while passive only change the viscosity. 646th solvent It is often used for nitro-enamels and some primers, but modern acrylic systems and base metallized paints require special branded diluents (R-12, 650th or original brand products).

⚠️ Attention: Never use gasoline, acetone in its pure form or white spirit to dilute acrylic car enamels. This will lead to the collapse of paint, loss of shine and complete loss of adhesion to the car body.

The ambient temperature dictates the choice of the solvent evaporation rate. If the garage is cold, the quick solvent will not have time to spread, and there will be a shaking. If the room is hot, a slow solvent can cause the paint to boil on the surface. Evaporation rate A critical factor that is often ignored by amateurs, focusing only on density.

Solvent compatibility table

Acrylic enamels require alcohol-ester mixtures | Basic metallics are often sensitive to acetone | Nitrocellulosic soils are afraid of strong solvents | Polyurethane varnishes need specific activators

Mixing technology and necessary proportions

The process of preparing the working mixture requires precision that cannot be provided by eye. For this, professionals use measuring cups with calibration. The standard mixing scheme of two-component materials (e.g. acrylic enamel + hardener) looks like adding a certain percentage of solvent to already mixed components. This usually amounts to 5% to 20% of the total volume of the mixture, but the exact figures depend on the manufacturer.

Let us consider a classic example of preparation of acrylic enamel. First, you mix the paint with the hardener in the proportion indicated on the jar (often 2:1 or 4:1). Only after careful mixing of these two components is added solvent. If you add it earlier, the chemical reaction of polymerization may go wrong, and the coating will lose strength.

For base coatings (metallic, 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 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 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 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 mother of father of mother of mother of mother of mother of father of mother of mother of mother of mother of mother of Here it is important not to transfuse the solvent, otherwise the metal will lose its effect, and the color will become pale. Consistency of the base It should be thinner than acrylic to ensure the correct orientation of the metal particles.

When mixing, use a clean wooden or plastic stirrer. Metallic objects can react with some components. The stirring should be intense to lift the sediment from the bottom of the jar, especially if the paint has been standing for a long time. Uniformity of mixture - the guarantee of the absence of discordance on the body.

Viscosity control: use of viscometer

How do you know if the paint is properly diluted? Experienced painters test this by the jet flowing down from the stirrer, but this method takes years of practice. For a guaranteed result, you need to use a viscometer - a funnel with a calibrated hole. The time it takes for paint to flow out of such a funnel shows its viscosity in seconds (ford seconds).

For different types of materials and diameters of the spray gun duse, there are their own standards of viscosity. If the paint is too thick, it will fall in large drops, forming a coarse shavern. If it is too liquid, the leaks are inevitable, and the cover will fall to zero. Viscosity measurement It should be carried out at a material temperature of 20°C, as the parameters change when heating or cooling.

The measurement process is simple: close the viscometer hole with your finger, pour the paint to the brim, remove your finger and turn on the stopwatch. Stop the time when the continuous stream will interrupt and go into the drip. The resulting number of seconds is compared with the table of recommendations for your spray gun.

Below is a table of indicative viscosity for various materials when using a spray gun with a duse of 1.3-1.4 mm:

Type of material	Recommended viscosity (sec)	Measurement temperature	Duse diameter (mm)
Basic enamel (metallic)	16-18 sec.	20°C	1.3 – 1.4
Acrylic enamel (2K)	18-22 sec.	20°C	1.4 – 1.5
Acrylic lacquer	18-20 sec.	20°C	1.3 – 1.5
Sound filler	20-24 sec.	20°C	1.6 – 1.8

Effect of temperature on the dilution process

The temperature in the paint room is the hidden enemy or assistant painter. The physics of the process is such that with increasing temperature, the viscosity of the liquid decreases, and the rate of evaporation of the solvent increases. If you dilute the paint at 15°C to its perfect viscosity and then put it in a 25°C chamber, it will become too liquid and will start to boil when sprayed.

In the cold season, it is necessary to use “fast” solvents, which manage to evaporate and allow the material to spread before drying. In summer, on the contrary, you need a “slow” version so that the paint does not dry out in flight, forming dry dust on the surface of the body. Temperature regime The choice of solvent labeling (Winter, Normal, Summer) is dictated.

It is also important to consider the temperature of the metal body. If you paint a hot hood, the solvent will evaporate instantly, leaving no time for the formation of a smooth surface. Painted surfaces should be heated to the temperature of the room in which the work is carried out.

⚠️ Attention: A sharp change in paint temperature during operation (for example, a draft or a working heater near the spray gun) can cause a defect in “blushing” or varnish mattage due to moisture condensation.

Features of preparation of different types of paint materials

Each type of car paint has its own chemical nature and requires an individual approach. Acrylic enamel (2K) is a system where chemical crosslinking of polymers takes place. Here it is critically important to accurately observe the dosage of the hardener. The lack of hardener will make the coating soft and unstable, and the excess - fragile. The diluent in this mixture is added last to adjust the viscosity under the gun.

Basic coverage (Base Coat) do not contain a hardener and dried solely by evaporating the solvent. Their main feature is the ability to keep metal or pearl particles in a suspended state. If you dilute the base too much or use the wrong solvent, the metal particles will fall to the bottom, and the color will become heterogeneous. The base often needs to be diluted more than acrylic to produce a thin, "fog" layer.

Soil fillers are the thickest materials. Their job is to fill in the risks and level the surface. They often require special diluents that do not affect the lower layers. Grunts You can’t dilute too much, otherwise they will lose their filling properties and shrink after drying.

Frequent errors and ways to fix them

One of the most common mistakes is to add a solvent directly to a shared can of paint when there are already residues from the previous time. This disrupts the chemical balance and can lead to unpredictable results. Always pour the right amount of material into a separate container. Cleanliness of packagings - the key to success.

Another mistake is to ignore filtering. Even if you’ve just opened a new can, there may be small clots or dust in the paint. Passing through the duo of the spray gun, they will get stuck and spoil the torch. Be sure to use a funnel with a disposable filter (grid) when pouring paint into the tank.

Do not try to resuscitate the paint that has started to thicken in the tank, adding a solvent there during the work. This will break the proportions and can cause defects. If the paint began to dry in the tank, it is better to pour it, wash the gun and prepare a fresh portion. Lifetime The finished mixture is limited, especially in hot weather.

⚠️ Attention: Residues of diluted two-component paint (acrylic + hardener) can not be stored in a closed container for the next time. The mixture will begin to polymerize and within a few hours will turn into a hard stone that will tear the jar.

Final recommendations for the ideal result

Paint preparation is the foundation of high-quality painting. Do not skimp on solvents and measuring tools, as the cost of materials is negligible compared to the work of repainting. Always follow the manufacturer’s instructions on the bank, but adjust the viscosity to your conditions and tool. Continuing practice And attention to detail will allow you to avoid shaking, stains and other defects.

Remember that the ideal result is achieved when the material lies flat, glossy layer without additional effort. If you have to press hard on the trigger or bring the gun close to the body, then the paint is diluted incorrectly. Adjust the viscosity, change the solvents depending on the season and always filter the material before pouring.

Can solvent 646 be used for acrylic enamel?

Use of solvent 646 for modern acrylic enamels (2K) is highly recommended. It is too aggressive and can cause clouding, color change, or adhesion disturbance. It is better to use original solvents of the same brand as the paint, or specialized analogues (for example, the 650th for some soils, but for the finish - only profile).

What to do if the paint is already diluted, but too thick?

Add a small amount of the appropriate solvent, mix thoroughly and measure the viscosity again with a viscometer. Add liquid in small portions (5-10 ml per glass) so as not to overdo it and not make the mixture too liquid, which will lead to leaks.

How long can you store diluted paint?

Single-component materials (base, nitroemali) can be stored in a sealed container for several months, if they are not thickened. Two-component mixtures (acrylic with hardener, varnish with hardener) are viable for only 2-4 hours (depending on temperature and brand), after which irreversible polymerization begins, and the material becomes unusable.

Do I need to heat the paint before painting?

Specially heat the paint is not necessary, it should be room temperature (about 20 ° C). Cold paint from a winter garage will have increased viscosity and can give condensation. Let it warm up naturally to room temperature before mixing.