Proper preparation of paintwork material (varnish) is the foundation of high-quality repair of the body, and often it is at the stage of mixing that fatal mistakes are made.
Many beginners underestimate the effect of viscosity on the spread of paint, forgetting that even the most expensive car-ename It will be defective if it is not properly prepared.
In this article, we will discuss in detail how to dilute auto-enamel for spray gun to get the perfect glossy layer without shaking and stains.
Basics of choice of solvent for automotive paints
The first step to success is to understand the chemical nature of your paint material, as there is no universal solvent suitable for all types of enamel.
The key parameter here is the evaporation rate, which directly affects how the paint behaves in the torch of the spray gun and how quickly it dries on the surface of the body.
Too fast. solvent It can lead to the appearance of matteness and the so-called “orange peel”, especially in hot weather or when working in a dry room.
On the other hand, the use of too slow composition in a cold shop will provoke the formation of undertightness and significantly increase the drying time, which is fraught with dust adhesion.
It is important to distinguish between active solvents that chemically interact with the film forming agent and diluents that only reduce viscosity without completely dissolving the resin.
For most modern systems, whether acrylic or base for varnish, special numbered solvents developed by the paint manufacturer are used.
Always check the technical passport (TDS) of a particular can of paint before mixing, as the chemical composition may differ even from one brand in different lines.
Classification of solvents by evaporation rate
Choosing the right type of diluent is dictated by the ambient temperature in the paint chamber, and ignoring this rule is a direct path to marriage.
Manufacturers offer three main types of solvents, each designed for a strictly defined temperature range.
Fast solvents are designed to work at low temperatures, usually up to 20 degrees Celsius, as they evaporate instantly and prevent the paint from boiling.
Medium (Standard or Normal) are versatile and are used in the range of 20 to 25 degrees, providing a balance between spreading and drying speed.
Slow compositions are needed in hot weather or at high chamber temperatures when evaporation needs to be slowed down to prevent surface defects.
Use of the quick-solvent at high temperature will lead to the fact that the paint will dry in the air, not having time to spread on the surface.
This phenomenon is called “dry fog” and requires a complete re-refining and repainting of the part, which leads to unnecessary financial costs.
The reverse situation with a slow solvent in the cold will cause a long curing, during which all the dust from the room will settle on the sticky surface.
Mixing proportions for different types of enamels
Accurate adherence to the mixing proportions of the components is critical to achieving predictable results and durability of the coating.
For different types of automotive paints, there are their own standard ratios, the violation of which changes not only the viscosity, but also the chemical structure of the future film.
Below is a table that will help you quickly navigate the necessary proportions for the most common materials.
| Type of paint | Proportion (Basic: Solvent) | Typical viscosity (DIN4) | Features |
|---|---|---|---|
| Acrylic enamel (2K) | 4:1 or 3:1 | 18-22 sec. | Requires the addition of a hardener |
| Basic paint (Basecoat) | 2:1 or 1:1 | 16-18 seconds | It does not contain a hardener, it dries with evaporation. |
| Lacquer (2K Clearcoat) | 2:1 or 4:1 | 18-20 seconds | High resistance, mandatory hardening |
| Sound filler | 4:1 or 3:1 | 25-30 sec. | High viscosity for filling the rice |
Note that the viscosity listed in the table is reference and may vary depending on the manufacturer's recommendations. paint-system.
For two-component materials such as acrylic enamel and varnishes, it is critically important to add not only a solvent, but also a strictly dosed one. hardener.
If you add too much solvent to the two-component mixture, you break the stoichiometric ratio, and the material may never stand at full hardness.
What happens if you break the proportions of the hardener?
Short hardener will lead to the fact that the coating will remain soft, will dry for a long time and lose shine. An excess of hardener will make the coating fragile, prone to chipping and cracking when heated.
Technology for preparing a working mixture
The process of preparing the working mixture requires not only precise proportions, but also the correct sequence of actions to ensure the homogeneity of the material.
First, you need to mix the main can with the paint carefully, since heavy pigments and fillers could settle to the bottom during storage.
After that, the desired amount of the base is measured, to which a hardener is added (if required by technology) and only the last solvent is introduced.
☑️ The procedure for mixing paint
The final stirring of all components should last at least 2-3 minutes to ensure complete dissolution and the absence of density gradients.
Use clean, dry measuring tanks with calibration, as determining the amount "by eye" is a gross professional error.
After mixing, it is recommended to let the mixture settle for 5-10 minutes (exposure) so that air bubbles that have fallen during intensive stirring come out of the material.
The viscosity of the finished mixture must be checked with a viscometer, since it is almost impossible to determine the readiness of the paint to work by eye.
Optimal viscosity ensures the correct formation of the torch and the uniform distribution of the material on the surface without the formation of “craters”.
If you use metallicThe quality of mixing affects the orientation of aluminum scales, which directly determines the color and effect of overflow.
Viscosity control and work with viscometer
Viscosity control is the only objective way to understand how to dilute the auto-enamel for spray gun at a particular time.
For measurement, a simple device is used - a viscometer, which is a funnel with a calibrated hole of a certain diameter.
The most common funnels of the DIN4 type, which allow you to measure the time of flow of 100 ml of liquid in seconds.
The measurement process is simple: immerse the funnel in a glass of paint, pick it up and record the time until the continuous stream is interrupted.
The obtained time in seconds is the viscosity according to DIN4, which should correspond to the values indicated in the technical map of the paint.
If the leakage time is too long, you need to add a little more solvent and mix the mixture again.
The viscosity of the paint is a dynamic parameter that varies depending on the temperature: the warmer the paint, the thinner it is, so measurements must be carried out at the working temperature of the material.
Therefore, all measurements are recommended at 20°C or to be adjusted if the conditions are different from the standard.
Regular calibration of the spray gun and checking the viscosity before each refueling of the tank will save you from unpleasant surprises in the form of shavern or neprocrastin.
Frequent errors and precautions
One of the most common mistakes is the use of aggressive solvents, such as: 646 or 647For expensive imported enamels.
These solvents may contain alcohols or other components that react with the chemical composition of the quality auto-enamel, causing curl or clouding.
Always use original diluents of the same series as the paint to ensure that all components are chemically compatible.
⚠️ Warning: Never use acetone or Kalosha gasoline to dilute modern car paints, as this is guaranteed to result in a defective coating and loss of adhesion.
Another mistake is saving on filtering: even in a new, newly opened can come across clots or debris that will score a duo of spray gun.
Be sure to filter the finished mixture through special funnels with mesh or paper filters (usually 125-190 microns) immediately before pouring into the tank.
Work with solvents is necessary only in a well-ventilated room and using personal respiratory protection.
Solvent vapors are heavier than air and can accumulate in the lower part of the room, creating an explosive concentration and risk of poisoning.
Keep open solvent cans tightly closed, as evaporation changes their composition and makes further use unpredictable.
Compliance with these simple safety rules and technology will allow you to avoid expensive alterations and get a result indistinguishable from the factory.
Can solvents from different manufacturers be mixed?
Theoretically, they can be if they are of the same type (for example, both are standard), but chemical additives can differ. It is better not to take risks and use products of one line in order to avoid stratification or changing the drying time.
Can I dilute the paint with gasoline or kerosene?
Absolutely not. Gasoline and kerosene have a completely different chemical structure, do not dissolve modern automotive resins and will lead to complete deterioration of the material and coating. Use only specialized solvents.
What to do if the paint curls when mixed?
If the paint curled up when adding a solvent or hardener (flakes or lumps), the mixture can no longer be saved. It is necessary to completely clean the container, thoroughly wash the tool and start mixing again with new components, checking their compatibility.
How long can you store the already diluted paint?
Single-component materials (bases, nitro) can be stored in a sealed container for several months, periodically shaken. Two-component mixtures (acrylic, varnish with hardener) are viable for only 2-4 hours, after which irreversible polymerization begins, and they must be disposed of.
How to wash the spray gun after work?
Immediately after work, wash the tool with the same solvent that was used for dilution (fast or standard). For final cleaning and preservation, you can use a special “washing” solvent, which is less aggressive to seals.