Painting Exterior Automotive Plastic: Is It Possible?

Painting the exterior plastic parts of your car is a great way to revitalise its appearance and make it look new again. Most plastic trims and parts of a car's exterior can be painted over, but it's important to note that this may vary depending on the make and model of the vehicle.

Before painting, it's crucial to properly prepare the plastic surface. This includes removing the part from the vehicle, if possible, sanding it down to remove any imperfections and create a rough surface for the paint to adhere to, and cleaning it with soapy water or a solvent-based cleaner to ensure it's free of dirt, grease, or other contaminants.

When it comes to painting, using a plastic adhesion promoter is recommended as it helps the paint bond better with the plastic surface. It's also important to work in a well-ventilated area and wear a mask to protect yourself from paint fumes and chemicals. Apply several thin coats of paint, allowing sufficient drying time between each coat, and finish with a clear coat enamel or lacquer for added protection and a glossy finish.

Removing plastic parts from the car

Removing plastic parts from your car is a simple process, but it does require some care and attention to detail. Here is a step-by-step guide to help you safely remove plastic parts from your car:

• Gather Your Tools and Materials: Before you begin, make sure you have all the necessary tools and materials. This includes items such as a screwdriver, a drop cloth or cardboard box, masking paper, painter's tape, and a lint-free microfiber towel.
• Identify the Plastic Parts: Determine which plastic parts you want to remove from your car. This could include trim pieces, bumpers, or other plastic components.
• Remove the Plastic Parts: Use a screwdriver to slowly remove the screws holding the plastic parts in place. Be careful not to lose the screws and keep them separate if you are removing multiple parts. Place the removed parts on a flat surface, such as a table or workbench.
• Clean the Plastic Parts: Mix soapy water in a bucket or sink by filling it with warm water and adding liquid dish soap. Use a scouring pad to scrub the plastic parts with light pressure. This will help remove dirt, grease, and create small abrasions for better paint adhesion. Rinse the parts with clean water and dry them with a lint-free microfiber towel.
• Prepare the Work Area: Spread a drop cloth or cardboard on the ground outdoors to protect the surface. Alternatively, you can use masking paper and painter's tape to cover the areas near the plastic parts if they cannot be removed. This will prevent paint from getting on other parts of your car.
• Sand the Plastic Parts (Optional): If the plastic parts have a shiny finish, you may need to sand them lightly with 200-grit sandpaper to create a rough surface for better paint adhesion. This step is optional but can help the paint stick better.
• Apply Primer (Optional): If you plan on painting the plastic parts, it is recommended to use a high-build primer specifically designed for plastic surfaces. Hold the primer can about 6 inches (15 cm) from the surface and apply thin coats, working your way back and forth. Allow the primer to dry completely before proceeding.

Remember to work in a well-ventilated area and wear protective gear, such as gloves, a mask, and goggles, when handling chemicals and paints.

Sanding and cleaning the plastic

Sanding the Plastic Surface:

• Start by using sandpaper with different grit levels to smooth out the plastic surface. Work your way up through the grit levels slowly to achieve the desired smoothness.
• The goal is to remove the shiny surface of the plastic, as this will help the primer and paint adhere better and provide a long-lasting finish.
• Take your time and work carefully to ensure an even and consistent sanding process.

Cleaning the Sanded Plastic:

• After sanding, it is crucial to clean the plastic part to remove any dirt, debris, or residue left by the sandpaper.
• Use warm water to clean the sanded plastic surface. You can also use a commercial degreaser for this step.
• Ensure that all soap residue is rinsed off, and then dry the plastic part with a lint-free microfiber cloth.
• Let the plastic air dry completely before proceeding to the next step. This typically takes around 1-2 hours, depending on the weather conditions.

Additional Tips:

• If the plastic surface still appears scuffed after drying, you can use 200-grit sandpaper to apply light pressure and create a smoother finish.
• It is recommended to wear a mask during the sanding process to avoid inhaling any dust or particles.
• Always work in a well-ventilated area to ensure proper airflow and prevent the buildup of dust and fumes.

Using the right primer

When it comes to painting exterior automotive plastic, using the right primer is essential to ensure the paint adheres well and that your hard work lasts. The primer you choose will depend on the type of plastic you're working with, and it's important to identify this before starting the painting process.

There are two main categories of plastics used in vehicles: Thermoplastic and Thermoset. Thermoplastic softens when heated, while Thermoset does not. Many flexible parts, such as front and rear fascia, are made of Thermoplastic, while mirrors and grilles are often Thermoset. Other types of plastic include Thermoplastic Olefin (TPO), Polyurethane (TPUR), Acrylonitrile Butadiene-Styrene (ABS), Sheet Moldable Compound (SMC), and Fiber Reinforced Plastic (FRP).

Identifying the type of plastic is crucial because it determines the compatibility of the primer and the adhesiveness of the filler. Some plastics, such as those made from Olefin Polymers, require an adhesion promoter to ensure the finish does not delaminate later.

Once you've identified the type of plastic, you can choose the appropriate primer. For larger plastic surfaces, an adhesion promoter in container format, applied with a spray gun, is a good option. An example of this is the SINNEK PL/1895 adhesion promoter, which is compatible with a wide range of plastics in the automotive sector.

If you're repairing patches or working on small surfaces, a spray primer for plastics is a better choice. These primers are easy to apply and provide good adhesion to different types of substrates. An example of this type of primer is the SP/1895 by SINNEK.

Regardless of the primer you choose, it's important to follow the manufacturer's instructions and allow adequate drying time between coats. This will ensure that your paint job is long-lasting and of high quality.

Choosing the correct paint

Painting exterior automotive plastic can be a tricky endeavour, but with the right tools and preparation, you can achieve a smooth and long-lasting finish. Here are some tips for choosing the correct paint for the job:

• Consider the Environment: Think about the environment in which the painted surface will be placed. If it will be exposed to high humidity or moisture, choose a paint with a high sheen value, such as satin, gloss, or semi-gloss. These finishes create a hard, moisture-resistant barrier that can be washed or scrubbed without damage.
• Drying and Curing Time: Pay attention to the drying and curing times of the paint. While spray paint may feel dry to the touch in about 15 minutes, it's important to allow 30 minutes of drying time between coats. Additionally, keep in mind that paint dries best at temperatures between 50 and 90 degrees Fahrenheit, with good airflow and ventilation.
• Size of the Paint Can: Typically, spray paint is available in 12-ounce cans, and one can will cover approximately 10 to 12 square feet of surface area. However, this may vary depending on the colour and the number of coats required. Lighter colours may need fewer cans, while darker colours may need more.
• Surface Material: Not all paints are suitable for all surfaces. For automotive plastics, look for paints specifically designed for these surfaces, such as polypropylene, polystyrene, resin, PVC, or fibreglass. These paints will ensure proper adhesion and coverage.
• Application Method: Spray painting is generally the best method for painting plastic, as it provides better coverage and a smoother finish. Brushing paint onto plastic can result in smearing, pooling, and visible brush strokes. If you must brush paint, consider priming the surface first to improve adhesion.
• Finish Options: Most spray paints for plastic result in a gloss or semi-gloss finish. However, you can also find specialty finishes such as metallic, hammered, textured, or camouflage. These finishes can give old plastic items a unique look, such as metal, stone, or other materials.
• Adhesion Promoter: When painting automotive plastic, consider using an adhesion promoter before applying the paint. This will enhance the adhesion of the paint to the plastic surface, resulting in a more durable finish.
• Primer: While some spray paints for plastic claim to not require priming, using a primer can improve the adhesion and durability of the paint. Look for a high-build primer specifically designed for plastic surfaces.
• Clear Coat Enamel: For added protection and a glossy finish, consider applying a clear coat enamel over the painted surface. This will harden the surface and protect it from future damage.
• Environmental Considerations: When working with spray paint, always work in a well-ventilated area to avoid inhaling fumes. Additionally, dispose of any leftover paint and materials properly to reduce environmental impact.

Applying lacquer and polish

Sanding and Priming:

Before applying lacquer, it's crucial to prepare the plastic surface. Start by removing the plastic part you plan to paint. Then, use sandpaper to smooth out any imperfections and create a matte finish. Work your way up from 150-grit to 1200-grit sandpaper. This step is crucial for achieving a smooth and long-lasting paint job. Once done, clean the sanded surface with soapy water to remove any debris.

Next, apply a primer to ensure the paint adheres well to the plastic. Hold the primer can about 6-7 inches from the surface and spray evenly. Apply 3-4 coats, allowing 15 minutes of drying time between each coat.

Applying Lacquer:

Now, you can add colour to the plastic part. Hold the spray paint can about 6-7 inches from the surface and apply thin, even coats. Spray in a back-and-forth motion, ensuring you don't miss any spots. Depending on the type of plastic, you may need to apply the paint while the primer is still wet or wait for it to dry completely. After each coat, allow sufficient drying time, typically around 10 minutes. Apply as many coats as needed to achieve full coverage.

Applying Polish:

To add shine and protection to the painted surface, apply a clear coat enamel or lacquer. Hold the can about 6 inches from the surface and apply thin, even coats, just as you did with the paint. Apply 4-5 coats of lacquer, allowing sufficient drying time between each coat, typically a few hours.

Once the lacquer is completely dry, use a microfiber polishing cloth to buff the surface gently. This will remove any remaining debris and give it a polished finish.

Tips:

• Always work in a well-ventilated area when spraying paint or lacquer.
• Wear a mask to avoid inhaling chemicals.
• If you can't remove the plastic part, use masking paper and painter's tape to protect the surrounding areas.
• If you're painting flexible plastic, wait for the adhesion promoter or primer to dry completely before applying paint.

Frequently asked questions