The quality of painting the car directly depends on how well prepared paint material. Even the most expensive enamel will lie unevenly if its viscosity does not meet the requirements of the spray gun. Too thick mixture will create a "shagrene skin", and too liquid will lead to sweats and a decrease in cover.
Many beginners ignore the recommendations of manufacturers, relying on intuition, which often ends in reworking the work. Right. paint-dilution It requires precision, temperature compliance and an understanding of the chemistry of processes. In this article, we will discuss all the nuances, from the choice of solvent to the final viscosity test.
The main task of the master is to turn a thick concentrate into an ideal working solution, which will be sprayed with a torch with a uniform density. To do this, you need to take into account the type of spray gun, the temperature in the chamber and the chemical basis of the material.
Solvent selection: process chemistry
The first and most critical step is to choose the right one. solvent. You can not use universal liquids "for everything", as they can cause coagulation (clotting) of the pigment or change the shade of enamel. The chemical composition of the diluent must strictly correspond to the basis of the paint: acrylic, alkyd, nitro or water base.
The evaporation rate of the solvent plays a key role in the formation of the film. Too rapid evaporation will lead to the fact that the material does not have time to spread, leaving a shaft. If the solvent dries too long, there is a high risk of leakage and dust getting to the fresh layer.
⚠️ Never mix solvents of different manufacturers or types (e.g. 646 and 647) in a single container. This can lead to unpredictable chemical reactions and defective coatings.
To work in a paint chamber, it is important to take into account the temperature. Summer solvents evaporate more slowly, allowing the material to spread out at high temperatures. Winter versions, on the other hand, are more volatile, which is necessary for operation in cool conditions or under accelerated drying.
- 🧪 Polar solvents (alcohols, ketones) - suitable for most enamels and soils.
- 💧 Nonpolar solvents White Spirits are used less often, mainly for oil paints.
- 🌡️ Temperature gradation Choose the evaporation rate based on the temperature in the shop (fast, medium, slow).
Definition of viscosity: instrumental control
The definition of viscosity "by eye" is a gross mistake leading to marriage. Professionals use a viscometer, most often a funnel type (for example, DIN-4 or Ford-4). This simple device allows you to measure the time of leakage of a fixed volume of liquid through a calibrated hole.
The measurement process is simple: the funnel is immersed in a container with paint, then lifted and started stopwatch. The time it takes to break the jet is viscosity in seconds. For different types of materials and diameters of the spray gun duse, these values differ.
If you don’t have a viscometer on hand, indirect methods can be used, but they are less accurate. However, for guaranteed results, especially when working with mother-of-pearl or “metallic”, instrumental control is mandatory.
| Type of material | Duse diameter (mm) | Viscosity (sec, DIN-4) | Temperature (°C) |
|---|---|---|---|
| Basic enamel | 1.3 - 1.4 | 16 - 18 | 20 |
| Acrylic lacquer | 1.3 - 1.5 | 18 - 22 | 20 |
| Sound filler | 1.6 - 1.8 | 20 - 25 | 20 |
| Liquid putty | 2.0 - 3.0 | 30 - 40 | 20 |
When heated, the material becomes thinner, when cooled, thicker. Therefore, all measurements and mixing must be carried out at a stable temperature, usually at a stable temperature. 20°C.
Mixing proportions: instructions
Each paint manufacturer indicates the exact mixing proportions on a bank or technical passport (TDS). Ignoring this data is a sure way to lose the warranty properties of the product. The standard designations look like 2:1, 4:1 or 3:1:10%.
The first digit always indicates the amount of the main product, the second - hardener, the third (if any) - the percentage of solvent. For example, a recording 4:1 + 10% 4 parts of paint require 1 part hardener and 10% solvent from the total mass of the mixture.
☑️ Pre-mixing check
For accurate dosing, use measuring containers or scales. Calibrated measuring glasses are convenient for the volumetric method, but scales give higher accuracy, especially for small volumes of work.
⚠️ Warning: Adding a hardener triggers an irreversible chemical reaction. Mix as much paint as you can produce during the pot life.
If you use ready-made repair kits, there the proportions can already be selected, and only the addition of the solvent to the desired viscosity is required. Read the label carefully: “Ready to spray” means that no hardener is required, only dilution.
Technology of mixing components
The order of addition of components is important. First, the base (paint) is poured into the container, then a hardener is added and thoroughly mixed. Only after that, a solvent is introduced to bring to working viscosity.
Stirring must be intense to lift heavy pigments from the bottom. Use a wooden or plastic stirrer, avoiding metal tools that may oxidize or scratch the container.
After adding all the components, allow the mixture to stand for 5-10 minutes. This is necessary for the release of air bubbles that formed during stirring, and to complete the initial chemical reaction.
What happens if you mix the hardener badly?
If the hardener remains at the bottom or in the form of individual clots, in these places the coating will never dry. Even after a month, the paint will remain sticky, and this can only be corrected by completely repainting the element with the removal of the old layer.
Use it. measuring-glass with a clear scale. Pour the components to the risks corresponding to the desired volume, holding the glass strictly vertically on a flat surface.
Setting up the spray gun for viscosity
After preparing the mixture, you need to adjust the spray gun. The pressure at the entrance to the gun and the viscosity of the paint are related parameters. For dense soils, greater pressure and a larger diameter duse are required, for liquid bases - less pressure.
Make a test pass on a piece of paper or metal. The torch should be smooth, without tears and "spitting". If the paint falls in large drops, add a little solvent. If fog and dry shavern are formed, the mixture is too liquid or pressure is high.
Adjustment of the torch is made by the screw on the shell of the sprayer. For wide surfaces, the torch is fully opened, for bottlenecks and local repairs, it is narrowed.
Before pouring paint into a spray gun tank, be sure to strain the mixture through a special filter funnel (sieve). This will delay dust, lumps and mottles that could have gotten into the container.
Do not forget to clean the spray gun immediately after work. The dried inside the canals of the paint will require aggressive chemistry and long soaking, and can damage seals.
Typical errors and their consequences
One of the most common mistakes is the use of poor-quality or inappropriate solvent. Cheap analogues can contain aggressive impurities that “lift” old soil or cause varnish clouding (the “whitening” effect).
Temperature disturbance is the second reason for marriage. Attempting to paint with cold paint in a cold chamber without heating will lead to the fact that the material will lie down with an “orange peel” and will not spread.
- 🚫 Overexpenditure Too thin paint requires more layers for cover.
- 💧 The leaks. The result of excessive dilution or slow solvent.
- 🌫️ Matness - occurs when using a quick solvent in heat or high humidity.
The main secret of perfect painting is not to save on solvents and strictly observe the temperature of the material, bringing it to 20 ° C before applying.
Also, interlayer drying time is often ignored. If you apply the second layer to the undried first, the solvent will be “locked” inside, causing a boil or bubble in the future.
FAQ: Frequently Asked Questions
Can you dilute the paint with gasoline or acetone?
Absolutely not. Gasoline contains oils and impurities that will spoil the coating. Pure acetone is too aggressive and can roll paint or dissolve plastic parts. Use only specialized solvents (646, 647, P-12 or branded products).
What to do if the paint thickens in the jar?
If the paint just settled, a thorough mixing will help. If it has turned into jelly or has lumps that do not break, the material is spoiled (polymerization has occurred). It is impossible to restore it, only to dispose of it.
How to store the remains of diluted paint?
Residues of paint with added hardener can not be stored, they will disappear in a few hours. If the hardener is not added (only paint + solvent), you can tightly close the jar and store in a dark place, but before reuse be sure to check the viscosity.
Does air humidity affect dilution?
Yes, at high humidity (>80%), you can not use fast-volatile solvents, since the condensate will get into the paint, causing matteness and bubbles. In such cases, special delayed solvents are used.