Direct mixing of two components - primer and activator - triggers an irreversible chemical reaction, so volumes must be measured strictly before application to the body.
Exact adherence to the proportions specified by the manufacturer in the technical documentation is the only way to guarantee the adhesion and anti-corrosion properties of the coating. Any deviation from the recipe leads either to insufficient metal etching or to the appearance of defects in the form of swelling or poor adhesion to subsequent layers.
Preparation process acid soil requires a clean measuring cup, scales or measuring ruler, as well as a working paint sprayer with a selected nozzle. It is important to understand that the viability of the finished mixture is limited by time, and it is strictly forbidden to store diluted material “in reserve”. The entire prepared volume must be completely used up during the working period, otherwise it will turn into an unusable mass.
Operating principle and composition of two-component systems
The basis of the material is polyvinyl butyl, which in combination with phosphoric acid creates the strongest chemical bond on the metal surface. Activator, added before use, contains the acid component necessary for the etching reaction. It is this reaction that converts iron oxides into stable compounds, stopping the development of corrosion even in microscopic pores.
Unlike one-component analogues, two-component primer requires mandatory mixing of the base with the hardener. Without adding an activator, the material will simply dry, but will not show its protective properties and will not create the necessary roughness for the next layer. The chemical interaction of the components occurs intensively, so the finished solution is highly aggressive towards metal.
⚠️ Attention: It is necessary to work with acid-containing materials only in a well-ventilated area and using high-quality personal respiratory protection equipment.
A properly prepared mixture ensures passivation of the surface, creating a barrier that prevents the access of oxygen and moisture to the metal. Violation of the mixing technology negates all the anti-corrosion properties of the coating, making further painting pointless. Understanding the chemistry of the process helps to avoid fatal mistakes when restoring a body.
Necessary tools and workplace preparation
To perform the work efficiently, you will need not only the material itself, but also the right tools. The main application tool is a pneumatic spray gun with a nozzle diameter of 1.3 to 1.6 mm, which allows you to create a fine spray. The compressor must provide stable pressure, usually in the range of 2-3 atmospheres, to avoid waste of material.
Before breeding reactive primer, you need to prepare a clean container. The use of dirty containers with residual solvents or old paints and varnishes is unacceptable, as this may conflict with the chemically active composition. Measuring containers must have clear graduations to accurately maintain weight or volume fractions.
Use transparent measuring cups with a printed scale to visually control the mixing process and the absence of separation of components.
The work area must be cleared of dust that may settle on the sticky layer of soil. The temperature in the spray booth or garage must meet the manufacturer's requirements, usually in the range of +15 to +25 degrees Celsius. At low temperatures, the polymerization reaction may not proceed correctly.
Exact proportions of mixing components
The key point of the entire technology is the correct ratio of base and activator. Manufacturers always indicate the proportions on the jar label or in the technical data sheet of the product, and this data cannot be ignored. The most common standard is a 1:1 ratio, but there are variations of 2:1 or 4:1 depending on the chemical formula of the particular brand.
Mixing is done immediately before application. First, the required amount of soil from the jar is poured into a clean container, then a strictly measured volume of activator is added. After this, the mixture is thoroughly mixed until a homogeneous consistency without streaks is obtained.
The table below shows approximate data on popular types of acid soils, but the instructions on your jar always take precedence:
| Product type | Proportion (Ground: Activator) | Mixture life time | Recommended pressure |
|---|---|---|---|
| Standard 1K+activator | 1: 1 | 30-40 minutes | 2.0 - 2.5 atm |
| Highly concentrated | 2: 1 | 45-60 minutes | 2.5 - 3.0 atm |
| Special (for aluminum) | 1: 1 | 20-30 minutes | 1.8 - 2.2 atm |
| Quick drying spray | Ready to use | N/A | N/A |
If you add too much activator, the coating will become brittle and may peel off along with the top layers of paint. A lack of acid will mean that a full etching reaction will not occur and the metal will remain vulnerable. Dosing accuracy - the key to the durability of the repair.
Application technology and drying time
After preparing the mixture, you must immediately begin application. Acidic soil applied in a thin, translucent layer ("wet on dry" is not used here, just a thin layer is needed). The goal is to coat the metal, but not pour it, since a thick layer may not dry out correctly and will shrink.
Usually one, maximum two thin layers are applied with interlayer drying. Drying time at room temperature ranges from 15 to 30 minutes. The surface should no longer be tacky, but should not completely polymerize to a “glass” state before applying the next layer, if required by the technology.
☑️ Control of primer application
It is important to respect the time intervals. If you over-expose the primer and it has completely cured, a light sanding may be required to improve the adhesion of the next coat, although many acidizers will allow the acrylic primer to be applied directly on its own within a certain window.
⚠️ Attention: Do not try to speed up the drying of acidic soil with infrared lamps or a hair dryer - this may cause the solvent to boil and destroy the coating structure.
Compatible with other materials and layers
One of the main features phosphate soils is their excellent compatibility with most repair paints and varnishes. Acrylic fillers, epoxy primers (with caution and within a time frame) and finishing enamels can be applied to the dried acid layer.
However, there are limitations. For example, it is not recommended to apply polyester putties directly to fresh acidic primer, as the styrene content in the putty may react and cause swelling. The correct sequence is: metal -> acid primer -> acrylic filler primer -> putty (if necessary) or paint right away.
If you plan to use epoxy primer over an acidic one, it is necessary to wait for the latter to dry completely (usually 30-60 minutes) and apply the epoxy within the processing window (often up to 24 hours) so that sanding is not required. Violation of the compatibility of layers leads to peeling of the entire “patty” of paint.
Typical errors and ways to resolve them
The most common problem is the appearance of dullness or a whitish coating, which often indicates an imbalance in the mixing proportions or high humidity in the room. If the soil is too thick, it may take a long time to dry and remain sticky. In this case, it is necessary to increase the drying time or carefully remove the defective layer with a solvent and reapply.
Poor adhesion, when the primer peels off as a film, indicates insufficient degreasing of the surface or the absence of an activator in the mixture. It can also be caused by application to a glossy, non-abrasive surface. The metal should be matte and clean.
What to do if the soil is curdled?
If you notice flakes or curdling in the glass, do not use the mixture. This occurs upon contact with incompatible solvents or when the expiration date has expired. Rinse the instrument thoroughly and prepare a new batch.
To eliminate shagreen or drips (if they were formed due to the gun being held too close), after complete polymerization, the defective area is sanded with P320-P400 abrasive, degreased and covered with a thin layer of primer.
Safety precautions and waste disposal
Working with acidic compounds requires strict adherence to safety precautions. Solvent vapors and acid fumes are toxic, so a proper respirator with carbon filters is a must. Liquid contact with skin causes chemical burns, so the use of nitrile gloves and safety glasses is standard.
The remains of the diluted soil should not be poured into the sewer or soil. Solidified residue in the can and used nozzles, gloves and rags should be disposed of as hazardous chemical waste in accordance with local environmental regulations. Acidic soil is a fire hazard, so it must be stored away from sources of fire.
The quality of surface preparation and the accuracy of mixing components determine 90% of the success of anti-corrosion protection of a car.
Frequently asked questions (FAQ)
Can acid primer be applied to rust?
Yes, one of the main functions of this material is to transform rust. However, the rust layer must be thin and adhere firmly to the metal. Thick, loose areas of corrosion must first be mechanically cleaned down to metal.
Do I need to sand acid primer before painting?
In most cases, sanding is not required if the coat is applied correctly and has no defects. Acrylic primer or paint is applied directly onto it. Sanding should only be done if there are streaks or if too much time has passed since application (more than 24-48 hours).
How to dilute thickened acidic soil?
You can only use special thinners recommended by the manufacturer (usually 646, 647 or specialized solvents for primers). Adding a diluent is possible only before mixing with the activator and in a volume of no more than 5-10%.
How long does it take for acid soil to dry at +20°C?
Touch dry time is approximately 15-20 minutes. Complete polymerization and readiness for applying the next layer (acrylic) usually occurs in 30-40 minutes, but it is better to follow the instructions for a specific product.