When restoring paint or completely repainting the car body, the quality and durability of the result directly depend on the surface preparation. One of the key elements in this process is jet-groundIt is often called an acid primer or wash primer. This material serves as a foundation that provides reliable adhesion of the finish layers with metal and protects the body from corrosion for many years.
Many motorists confuse different types of primers, which can lead to fatal repair errors. Jet soil It works on the principle of chemical reaction with metal oxides, creating the thinnest, but incredibly strong adhesive film. Unlike insulating compounds, it does not just fill irregularities, but penetrates the metal structure, preventing the spread of rust under the paint layer.
Understanding the features of working with this material is critical to obtaining a professional result. Improper application, misalignment of mixing proportions, or ignoring drying time can negate all the effort and budget spent on expensive enamel. In this article, we will take a detailed look at the composition, application technology and typical errors to make your car look flawless.
Chemical composition and principle of operation
Basis jet-ground is a polyvinyl butyral resin, which acts as a binder. However, the main active component is orthophosphoric acid, which triggers the process of passivation of the metal. Upon contact with the surface, the acid reacts with iron oxides, turning them into stable phosphate compounds that block further corrosion development.
The two-component system, to which most quality primers belong, requires mixing the base with a special hardener immediately before use. Exactly. acidic It triggers an irreversible chemical reaction, after which the material quickly loses its properties. The viability of the finished mixture is usually from 15 to 30 minutes, which dictates its rules of operation.
โ ๏ธ Warning: Never apply jet soil to existing paintwork or putty. The acid can cause the old layers to swell and loss of adhesion, which will peel off the entire structure in a short time.
After drying, a thin film with a thickness of only 8-15 microns is formed. It is not designed to level out defects, but creates a perfect chemical and mechanical bond between the bare metal and subsequent layers of filler or paint. Polyvinylbutyral The composition provides high elasticity and resistance to vibrations, which is especially important for mobile body elements.
Key Benefits of Using a Primer
Use of the acid-soil It gives a number of undeniable advantages over one-component acrylic analogues when working with problem surfaces. First of all, it is the highest adhesion to non-ferrous metals such as aluminum, galvanized steel and stainless alloys, which are often used in modern cars.
In addition, the material provides excellent protection against film corrosion. Even if there are microscopic oxidation foci on the metal that cannot be removed mechanically, phosphoric acid neutralizes them. It does. jet-ground indispensable in the repair of thresholds, arches and other areas exposed to aggressive environmental influences.
An important aspect is the universality of application. The material perfectly lies on both smooth and slightly rough surfaces prepared with abrasive. It does not require complex equipment to apply and can be used both in a professional service environment and in a garage with basic skills.
- ๐ก๏ธ It creates powerful anti-corrosion protection due to chemical passivation of metal.
- ๐ Provides ultra-high adhesion to any metal alloys, including complex.
- โฑ๏ธ It has a very short drying time, allowing you to speed up the repair process.
- ๐ง It does not absorb moisture and prevents its penetration to the metal.
Differences from epoxy and acrylic primers
A common question that arises from the masters: jet-ground Is it different from epoxy? Epoxy compounds create a thick, hard and completely insulating film that physically cuts off the access of oxygen and moisture. They are ideal for primary protection of new metal or after sandblasting, but require perfect preparation and have a long drying time.
Acid primerIt works chemically and creates a very thin layer. It is not an insulator in the full sense of the word, so over it must be applied secondary soil (acrylic filler) or paint. Epoxy in some cases can be used as the final insulating coating under the paint without filler, if the technology allows.
Acrylic soils-fillers serve to level the surface and fill the drawings from abrasive. They do not have the anti-corrosion properties of acid and do not give such adhesion to smooth metal as epoxy or wash primer. Therefore, in a professional painting scheme, these materials are often used together to achieve maximum effect.
| Parameter | Reactive (Acid) | epoxy | Acrylic (Filler) |
|---|---|---|---|
| Basis | Polyvinylbutyral + acid | Epoxy resins | Acrylic resins |
| Metal adhesion | Chemical (maximum) | Mechanical (high) | Mechanical (medium) |
| Thickness of layer | 8-15 ฮผm | 30-100 ฮผm | 50-200 ฮผm |
| Grindability | Not grinding (too thin) | Hard to grind. | Easy to grind. |
The jet soil is an adhesive bridge, not an insulator. Its main task is to glue the subsequent layers to the metal, rather than leveling the surface.
Technology of application and surface preparation
The quality of the surface preparation determines 80% of the success of the entire repair. Before application jet-ground The metal must be cleaned of dirt, oils, silicone and old paint to a clean base. For degreasing, it is recommended to use special antisilicone solvents, rubbing the surface with a clean rag in two passages.
The machining is carried out with abrasive materials with a gradation P80-P180. A rough risk will provide better mechanical adhesion, but too deep scratches can pass through the thin layer of the primer. After grinding, it is necessary to carefully remove the dust with compressed air and re-degrease the surface.
โ๏ธ Preparation for application of reactive soil
The mixing of components must be strictly according to the manufacturer's instructions. Usually, 1 part of the base accounts for 1 part of the activator, but the proportions can vary. Mix the composition thoroughly for 1-2 minutes to ensure uniformity. The material must be applied quickly before active polymerization begins.
Application is carried out with a spray gun with a diameter of duse 1.3-1.5 mm at a pressure of 2-3 atmospheres. It is necessary to apply 1-2 thin wet layers with interlayer drying for 5-10 minutes. Do not try to pour the surface "in fat", this will lead to defects and long drying. Jet soil It should be placed in a semi-transparent layer.
โ ๏ธ Warning: Work only in a well-ventilated room with proper ventilation. The vapors of solvents and acidic components are toxic, so the use of a respirator with carbon filters is mandatory for respiratory protection.
Drying time and grinding of the coating
One of the features acidic soil It's a quick drying out. At a temperature of +20 ยฐ C and normal humidity, surface drying takes 10-15 minutes. However, full polymerization and evaporation of solvents can take anywhere from 30 minutes to several hours, depending on the thickness of the layer and environmental conditions.
It is important to understand that jet-ground It's practically non-surfaced. Its thickness is so small that any abrasive passage will immediately remove the protective layer to the metal, depriving the whole operation of meaning. If you find defects (dust, shavern) after drying, they should be carefully removed with the abrasive P1000-P1200 locally, and then apply another thin layer of the primer.
Can I dry the jet soil with an infrared lamp?
Yes, you can. Infrared drying greatly speeds up the process, reducing the drying time to 5-7 minutes. However, the surface temperature should not exceed 60ยฐC, so as not to provoke boiling of the solvent and the appearance of pores.
After complete drying, the surface is ready for application of the secondary soil-filler. If you do not plan to continue working immediately, open acidic It can be left airborne for up to 7-10 days (depending on the brand), after which its adhesive properties may decrease and it will require re-activation or easy re-refusing.
- ๐ก๏ธ The standard drying time at 20ยฐC is 15-30 minutes.
- ๐ฅ IR drying speeds up the process, but requires temperature control.
- ๐ซ It is not recommended to grind the layer because of its small thickness.
- The "window" for the next layer is from 30 minutes to 7 days.
Common Errors and How to Resolve Them
The most common mistake is the application jet-ground Putty. Phosphoric acid does not have adhesion to polyester resins that are part of the putty. At best, the layer will simply fall off, at worst - the acid will destroy the structure of the putty, and stains will appear through the paint. Only insulating soil is applied to the putty.
Another common problem is the violation of the mixing proportions. An excess of the activator will make the coating brittle and peeling, and the lack will not trigger the passivation reaction, and the metal will remain unprotected. Always use measuring tanks or scales to accurately dosing components.
โ ๏ธ Note: Do not apply polyester putty overhead over jet soil. Acid vapors remaining in the pores can cause swelling of the putty. First we put the patty, then we put the metal with acid around, then we cover everything with epoxy or acrylic.
Ignoring interlayer drying also leads to defects. If the second layer is applied too early, the solvent from the bottom layer can boil and create craters or bubbles. Follow the technological pauses specified by the manufacturer on the packaging wash primer.
If you accidentally applied jet soil to the putty, do not try to fix it with drying. Wait for complete drying, carefully grind this area to metal or clean putty and degrease the surface again.
Using an expired activator is a hidden threat. The shelf life of the acid component is limited. If the activator has become cloudy or changed the consistency, the reaction may not go through and the adhesion will be zero. Always check the dates on the banks before starting work.
FAQ: Frequently Asked Questions
Can I paint directly on reactive soil without acrylic?
Technically, some systems allow this, but are not recommended. Jet soil has a porous structure and can absorb a solvent from the paint, causing mattage or change in hue. Besides, he's not hiding the risk. It is better to apply 1-2 layers of acrylic soil-filler for the ideal result.
Is the acid soil compatible with epoxy?
Yeah, it's a great bunch. First applied acid-primer for adhesion and anticorrosion protection, and on top of it, after drying, an epoxy soil is applied to create a thick insulating layer. The main thing is to observe the time intervals of drying between layers.
Do I need to grind the reactive soil before applying acrylic?
No, it is not necessary to grind it and even harmful, since you will remove the protective layer. If there is dust on the surface, it can be carefully removed with a sticky napkin or blown with air. The acrylic soil perfectly lies on the unspoiled (but dried) layer of acidic acid.
What is the storage period of the finished mixture?
Prepared mixture jet-ground It's not stored. After the activator is added, the chemical reaction is continuous. The viability of the mixture is from 20 minutes to 1 hour. The residues in the jar or spray gun will have to be thrown away, as they will turn into a gel.