Do-it-yourself selection of car enamel and refilling an aerosol can

Repairing a car's paintwork is always stressful for the owner, especially when it comes to chips, scratches or scuffs in visible places. A visit to a specialized service station is often expensive, and the work can take weeks to complete. That is why many car enthusiasts are considering the option of repairing defects on their own using a ready-made aerosol can, matched exactly to the color of the body.

However, simply buying “paint for Ford” or “enamel for BMW” at your local store is not enough. Auto enamel is a complex chemical substance, the properties of which vary depending on the year of manufacture, manufacturer and even batch. An incorrect selection will result in the repaired element having a different shade, creating a “patchwork” effect instead of a perfect surface. In this article we will look at the intricacies of selecting the composition, mixing technology and the correct process for refilling an aerosol can.

Modern tinting methods make it possible to recreate color with an accuracy of 98-99%, which makes invisible repairs a reality even in a garage environment. But the success of the operation depends on strict adherence to the technology, the cleanliness of the equipment used and an understanding of the physical and chemical processes of drying materials. Ignoring the nuances of preparation can negate all efforts and ruin the appearance of the car.

Factory Paint Code Identification

The first and most critical step is to determine the exact color code of your car. Many people mistakenly rely on the name of the color in documents or the visual resemblance to a fan of flowers, but this is absolutely not enough. Factory code is a unique identifier that ensures the shade matches the manufacturer's original specifications.

The location of the code plate varies depending on the make and model of the machine. Most often it is located on the body pillar between the doors, in the engine compartment on the partition of the engine compartment, or in the trunk under the carpet. There may be several codes indicated on the plate, so it is important to find the one indicated as “Color”, “Paint” or “Farbe”.

• 🚗 European cars: The code is often located on the driver's door pillar or in the spare wheel well (for example, VW, Audi, BMW).
• 🚙 Asian auto industry: the plates are usually located under the hood on a glass or partition (Toyota, Honda, Mazda).
• truck American models: information is often duplicated on the door pillar and in the trunk, but the recording format may differ.

⚠️ Attention: If the code plate is no longer legible or is missing, do not try to guess the color from the catalog. In this case, the only correct solution will be a computer selection of paint based on a sample taken from a less noticeable part of the body, for example, the inside of the gas tank flap.

Once you have found the code, write it down in its entirety, including letters and numbers. Even one missing digit can change the hue from “silver” to “blue-gray.” Complex colors such as chameleon or three-layer pearls may require an additional varnish or intermediate coat code.

Computer selection and spectrum analysis

Having a paint code is only half the battle. The fact is that over the years of operation, the car fades in the sun, is exposed to reagents and precipitation. New paint, mixed strictly according to the factory recipe, may look brighter or darker than a faded body. Therefore professional computer selection often includes not only code mixing, but also shade adjustments.

The selection process takes place in specialized tinting studios using high-precision scales and spectrophotometers. The master takes a color sample, and the program calculates the required proportions of pigments. Spectral analysis technology allows you to take into account the degree of burnout and the individual characteristics of the coating of a particular car.

It is important to understand the difference between acrylic enamels and metallized compositions. Metallics require the addition of aluminum powder of a certain grind, which affects the light and shade. If you mix up the powder fraction or percentage, the metallic effect will look dirty or grainy, giving away the repair area.

Coverage type	Features of selection	Required Components
Acrylic (Solid)	Easier to select, less dependent on viewing angle	Base, solvent, hardener
Metallic (Basecoat)	Requires precise grain calibration and is difficult to apply	Base enamel, solvent, varnish
Pearl	Three-component system, layer thickness is critical	Primer toner, base with pearl, varnish
Kandy	Translucent pigments applied to the background	Tinted primer, transparent enamel, varnish

When ordering tinting, be sure to inform the technician about the nature of the defect. If you are painting over a small scratch, the shade should be selected taking into account the fading of the old coating. If you plan to paint an entire part (door or wing), then it is better to use a clean recipe according to the code, since the new part will contrast with the old body in any case.

Necessary equipment for refueling

To turn liquid paint from a can into a high-quality aerosol, it is not enough to simply pour it into a container. Special tools are required to obtain the correct flame size and pressure. The main device is gas station or manual aerosol can refiller.

Such devices allow you to pump the required amount of propellant (liquefied gas) into the can and create operating pressure. The use of household compressors, or especially blowing with your mouth, is strictly prohibited - this will lead to unstable atomization and damage to the material. You will also need funnels, measuring cups and filters.

Particular attention should be paid to the selection of the cylinders themselves. They must be designed for a pressure of at least 12-15 atmospheres. Cheap cans may not withstand gas pressure or have a low-quality valve that will begin to poison the mixture immediately after filling. The presence of a glass ball inside the container is a huge plus, as it ensures high-quality mixing of the components when shaking.

⚠️ Attention: All work with propellant gas (usually a mixture of propane-butane or dimethyl ether) should be carried out in a well-ventilated area, away from open flames and sources of sparks. The gas is heavier than air and can accumulate in low areas, creating an explosive mixture.

To clean the valve and flush the system after use, use a special aerosol system cleaner or a regular solvent (646, 647) compatible with your paint. This will extend the life of your equipment and allow it to be used for other colors in the future.

Component mixing technology

The process of preparing the mixture begins with thoroughly mixing the base enamel in the original jar. Pigments tend to settle to the bottom, forming a dense layer. If uniformity is not achieved at this stage, the color in the can will be different from the color in the jar, and all previous matching efforts will be lost.

Use a clean wooden or plastic stirring stick. Lift sediment from the bottom and walls, achieving absolutely uniform color and consistency. For two-component systems (acrylic with hardener), mixing must occur strictly according to the proportions specified by the manufacturer, usually 2:1 or 4:1.

• 🎨 Filtration: Before pouring the paint into the container, it is necessary to filter it through a special funnel filter (nylon stocking or paper filter). This will remove any lumps or dust that may clog the aerosol valve.
• 🧪 Adding solvent: For aerosol application, the viscosity of the paint should be lower than for a spray gun. Add 10-15% of solvent by volume of paint to ensure a stable spray pattern.
• 🌡️ Temperature: All components (paint, varnish, solvent) must be at room temperature (about 20°C). Cold paint mixes less well and may result in incorrect viscosity.

After mixing and filtering, let the mixture sit for a couple of minutes to release any air bubbles. Then carefully pour the finished mixture into the body of the aerosol can using a funnel. Do not fill the jar full - you need to leave about 20-25% of the volume of free space for gas and ball.

The secret to perfect viscosity

Experienced painters check the readiness of the mixture for filling using the “stopwatch method”. A drop of paint flowing from a stick should have a certain fluidity. If it flows like water, there is a lot of solvent, if it stretches like a thread, there is not enough. The aerosol needs the consistency of full-fat milk.

The process of filling and sealing the cylinder

The most crucial moment is filling the gas cylinder. Place the paint can on the filling device platform and secure it. Place the spray valve (or adapter) onto the neck of the bottle. Make sure the rubber seal is intact and fits tightly.

Connect the propellant gas cylinder to the filling fitting. Press the throttle lever in short bursts of 2-3 seconds. Take pauses between presses to allow the gas inside the cylinder to warm up and fill the volume. Sudden filling may cause the cylinder to freeze and reduce filling efficiency.

Procedure:
1. Shake the paint can.
2. Install on the filling machine.
3. Press the gas supply button (3-4 times for 2 seconds).
4. Relieve pressure from the valve (gently press the nipple).
5. Repeat the gas supply cycle 2-3 more times.
6. Check the pressure by rocking (it should hiss).

After filling with gas, you need to install the spray head. To do this, turn the can upside down and press the valve for 1-2 seconds so that the paint gets into the head channels. This will prevent the paint from drying out in the nozzle the first time you use it. Now the container is ready for use, but it needs to be shaken thoroughly for 2-3 minutes.

Testing and application technique

Before applying paint to your car, be sure to test paint on a scrap piece, metal plate, or cardboard. This will allow you to evaluate the quality of the torch, the pressure and, most importantly, the color match after drying. Remember that wet paint always looks darker than dry paint.

The aerosol application technique differs from working with a spray gun. The balloon must be held strictly perpendicular to the surface at a distance of 20-25 cm. Movements must be smooth, reciprocating. Start spraying at the edge of the part and end behind it to avoid the formation of droplets (sprays) at the beginning and end of the pass.

Apply the material in several thin layers. The first layer is thin, dusty, for adhesion. The second and third are more saturated, covering the surface. Between layers, maintain a pause of 10-15 minutes (interlayer drying time) so that the solvent has time to evaporate.

If you are working with metallics, after the base has dried (usually 30-40 minutes), you need to apply 2-3 layers of acrylic varnish for protection and gloss. You can also put the varnish in an aerosol can or use ready-made varnish in a spray. After complete drying (it is advisable to wait 24 hours), the surface can be polished.

What to do if the paint starts to bubble or shagreen?

The appearance of shagreen (orange peel) or bubbles most often indicates that the paint is too thick, the distance to the surface is too small, or the ambient temperature is high. This can be corrected only after complete drying: sand the defect with P1000-P1200 abrasive and apply the layer again, adding more solvent.

How to store leftover paint in a can?

To store, turn the cylinder upside down and press the valve for 2-3 seconds until clean gas comes out. This will clear the channel of paint, and next time the balloon will not spit. It should be stored in a cool place, away from batteries and the sun.

Is it possible to mix paint from different manufacturers in one bottle?

Strongly not recommended. Chemical bases (alkyds, acrylics, urethanes) may react, curdle, or never dry. Use products from the same line or pre-test mixing in small volumes.

How long does it take for paint to dry in an aerosol can?

Touch-drying time is 15-30 minutes, but complete polymerization and strength gain occur within 2-3 weeks. During this period, it is not recommended to wash the car with aggressive chemicals or use polishes with abrasives.