Recovery of a car paintwork or protection of body parts from corrosion always begins with surface preparation, and the key step here is priming. Often, the masters are faced with a situation where soil in the jar was too thick for spraying through the spray gun, or its volume is not enough to process the entire part. At such moments, a critical question arises: what exactly can be diluted material, so as not to violate its chemical formula and adhesive properties.
Wrongly selected solvent is able to completely spoil the coating, causing its folding, clouding or lack of polymerization. In the automotive industry, where the requirements for durability and body appearance are extremely high, experiments with chemistry are unacceptable. You need to clearly understand the differences between the types of primers, since there is simply no universal remedy for everything in nature.
In this article, we will take a closer look at what chemical components are used to liquefy different soil types, consider the compatibility table, and learn how to avoid fatal errors in the preparation of the mixture. Consistency The working solution directly affects the quality of the final result, so the selector (diluent) should be approached with maximum responsibility and knowledge.
Classification of primers by type of base
Before opening the can with the solvent, it is necessary to identify the type of primer itself. Automotive soils are divided into several main categories, and each of them requires a strictly defined chemical environment. The most common group is epoxyThese are the most durable corrosion-resistant film and are often used to protect bare metal. They are two-component and require the addition of not only a solvent, but also a hardener.
The second popular category is acrylic filling soils, the task of which is to level out small defects and create a base for enamel. They can also be one or two-part. Standing apart. acidic (phosphate) soils that are applied the thinnest layer directly to the metal for chemical passivation of corrosion. Their chemical composition is most aggressive and sensitive to foreign additives.
⚠️ Warning: Never try to dilute two-component soil (epoxy or polyurethane) with water or a universal solvent. This will lead to an irreversible chemical reaction and the material will have to be discarded.
There are also special soils, such as zinc-filled or insulating, which have their own unique viscosity requirements. Understanding the chemical nature binder In your bank, it is 90% of your success. If you use an inappropriate diluent, you risk getting a coating that will start peeling off after months or even weeks of vehicle operation.
The main types of solvents and their properties
The autochemistry market offers a wide range of liquids designed to change the viscosity of paint materials. The most common option is White SpiritIt is a mixture of liquid hydrocarbons. It has a low toxicity compared to other, but has a specific odor and dries for a long time, making it suitable mainly for oil and some alkyd soils, but not for modern automotive systems.
For professional automotive work, complex mixtures based on solventxylene, acetone and butylacetate. These components are part of branded diluents labeled as "Base", "Thinner" or "Diluent". The rate of evaporation of such solvents varies: there are “fast” versions for operation at low temperatures and “slow” for hot climates, which allows you to control the process. flowability material.
- 🧪 Solvent A powerful solvent used for many synthetic resins, but requiring caution due to its high toxicity.
- 🧪 xylene - often included in the composition of diluents for epoxy soils, providing good solubility.
- 🧪 acetone Very volatile and aggressive, used in small doses or in mixtures, but can cause defects if used incorrectly.
- 🧪 Alcohols. - are used rarely and only for specific types of primers, most often as an additive.
It is important to note that using pure chemical reagents (such as technical acetone) instead of specialized automotive diluents is a risk. Branded products contain balancing additives that regulate the rate of evaporation and prevent the boiling of paint. Evaporation must be consistent with the temperature in the paint chamber, otherwise the soil will either not have time to spread, or boil on the surface.
Table of compatibility of soils and solvents
To avoid costly mistakes, it is necessary to know which solvent corresponds to which type of soil. Below is a reference table that will help you navigate the compatibility of materials. Remember that the manufacturer always takes priority: if the instructions indicate a specific name, use it.
| Type of soil | Recommended solvent | Prohibited substances | Features of mixing |
|---|---|---|---|
| Epoxy (2K) | Special solvent for epoxides (usually based on xylene/butanol) | Water, alcohols, White Spirit | Requires the addition of a hardener before dilution |
| Acrylic (2K) | Universal Acrylic Diluent (Base) | 646 (with caution), petrol | Dilute after mixing with hardener |
| Acid (1K) | Special diluent for acid soils | Any alkaline solutions, water. | It is applied in a very thin layer, does not require strong viscosity. |
| Alkyd (1K) | White Spirit, Solvent | Water, acetone (pure) | Long drying time, suitable for hidden cavities |
As you can see from the table, compatibility Components are not just a recommendation, but a strict requirement. Attempting to dilute epoxy soil with a conventional solvent for nitro paints can lead to the fact that the soil will never dry out or lose its anti-corrosion properties. The chemistry of polymers is complex, and the imbalance of solvents changes the structure of the film that is formed.
When working with the table, it is also worth considering that some manufacturers produce their own line of diluents, optimized for their products. The use of a “foreign” solvent, even if it is suitable for the type (for example, acrylic), can lead to a change in hue or adhesion. Always check the product technical passport (TDS) which indicates the exact proportions and types of compatible materials.
What to do if there is no branded solvent at hand?
In an emergency, if you need to finish work urgently, you can use a high-quality universal acrylic diluent (Base) for 2K acrylic soils. However, for epoxy and acid soils, replacement is not recommended. If you have diluted the soil with an inappropriate composition, it is better not to apply it to the body, but to use it for technical purposes or dispose of it so as not to risk all painting.
Mixing proportions and viscosity control
Determining the amount of solvent is an art that is based on precise measurements. It is standard practice to add a diluent in the range of 5% to 15% of the volume of the finished mixture (soil + hardener). However, these figures can vary depending on the ambient temperature and diameter of the spray gun duse. Viscosity The main parameter that needs to be controlled.
For accurate measurement of viscosity, professionals use a viscometer (funnel). If you do not have it, you can focus on the flow of the mixture with the stirring ruler: it should flow down with a smooth trickle, but do not drip too quickly. Excessive dilution (>20%) leads to a fall in the “dry residue”, increased shrinkage of the soil and loss of anticorrosion properties. Insufficient Dilution will cause shashaven (“orange peel”) and poor adhesion.
☑️ Control of mixture preparation
Temperature plays a critical role: in heat, the solvent evaporates faster, so the mixture can thicken.