RC Polycarbonate Body Painting: A Pro Guide

So, you've got your brand-new remote-control (RC) car body shell, a gleaming, transparent canvas awaiting your personal touch. Unlike their full-sized counterparts, RC car bodies, particularly those made from polycarbonate (often referred to as Lexan), present a unique and fascinating challenge: they're painted from the inside. This seemingly counter-intuitive approach is precisely what gives these shells their incredible durability and a factory-finish look, protecting your intricate paintwork from crashes, scratches, and the general wear and tear of high-speed RC action. If you're ready to transform that clear shell into a vibrant, custom masterpiece, you've come to the right place. This guide will walk you through every step of painting polycarbonate RC bodies, ensuring you achieve a professional, long-lasting finish.

Why Paint Polycarbonate RC Bodies from the Inside?

The primary reason for painting polycarbonate bodies from the inside is protection. When the paint is applied to the interior surface, the tough, flexible polycarbonate acts as a clear protective layer on the outside. This means that when your RC car inevitably tumbles or scrapes against obstacles, the impact is absorbed by the plastic shell, leaving your meticulously applied paint job untouched and pristine. Painting the exterior would lead to immediate chipping and scratching, quickly ruining your hard work. This 'inside-out' method also contributes to a deeper, more realistic appearance, as the light reflects off the paint through the clear plastic.

Essential Tools and Materials You'll Need

Before you even think about spraying paint, gathering the correct tools and materials is paramount. Using the wrong products can lead to disastrous results, so invest in quality items specifically designed for RC body painting:

• Polycarbonate RC Body Shell: Your blank canvas.
• RC Polycarbonate Paints: Crucially, these are not ordinary spray paints. They are specially formulated to adhere to polycarbonate and remain flexible when dry, preventing cracking and peeling. Brands like Tamiya PS, Pactra, and Pro-Line are highly recommended.
• Lexan Scissors or Curved Body Scissors: Essential for trimming the body accurately.
• Body Reamer or Hobby Knife: For creating precise body post holes and other openings.
• Degreaser or Mild Dish Soap: For thoroughly cleaning the inside of the body.
• Microfiber Cloths: Lint-free cloths for drying and wiping.
• Masking Tape: High-quality masking tape, such as Tamiya masking tape, is crucial for sharp lines and preventing bleed-through. Various widths are useful.
• Liquid Mask (Optional): For complex designs, a liquid mask can offer more flexibility than tape.
• Protective Gear: A good quality respirator mask and gloves are essential for safety when spraying paints.
• Hobby Knife or Craft Blade: For cutting masking tape and fine details.
• Hair Dryer (Optional): Can speed up drying times between coats, but use on a low, cool setting.
• Paint Stand or Workstation: Something to hold the body securely while you work.
• Rubbing Alcohol or Isopropyl Alcohol: For final clean-up before painting.

Preparation: The Foundation of a Flawless Finish

Preparation is arguably the most critical step in RC body painting. Skimping here will inevitably lead to frustration later. Patience and attention to detail will pay dividends.

1. Trimming the Body Shell

Most RC bodies come with excess plastic around the edges. Carefully use your Lexan scissors to cut along the moulded trim lines. Start with a rough cut, leaving a little extra material, then go back for a finer, more precise cut. Take your time, as jagged edges can lead to cracks later. If your body requires cutting out wheel arches, use the reamer or a sharp hobby knife for a clean, round cut.

2. Cleaning the Interior Surface

Even a brand-new body shell can have mould release agents, dust, or fingerprints on its interior surface. These contaminants will prevent paint from adhering properly. Wash the inside of the body thoroughly with mild dish soap and lukewarm water. Gently scrub with a soft cloth or your fingers. Rinse thoroughly with clean water, ensuring no soap residue remains. Allow the body to air dry completely, or use a clean, lint-free microfiber cloth. Crucially, avoid touching the clean interior surface with bare hands after this step; wear gloves.

3. Peeling the Outer Protective Film

Many polycarbonate bodies come with a thin, clear protective film on the *outside* surface. This film protects the body during shipping and handling. It's vital to leave this film on during the entire painting process, as it will protect your exterior from accidental overspray or scratches. You'll only remove it at the very end.

4. Marking Body Post Holes (If Applicable)

If your body isn't pre-drilled, you'll need to mark and drill the body post holes. The easiest way to do this is to temporarily mount the body onto your RC chassis, ensuring it's centred and at the desired height. Use a fine-tipped marker or a body post marker to mark the exact locations of your chassis's body posts on the inside of the shell. Then, use your body reamer to slowly and carefully enlarge these holes to the correct size. Start small and gradually widen them for a snug fit.

Mastering Masking Techniques

Masking is where your design truly takes shape. Whether you're aiming for a simple two-tone scheme or a complex multi-colour masterpiece, proper masking is non-negotiable for crisp lines and clean transitions.

Window Masks

Most RC bodies come with pre-cut window masks. Carefully peel these off their backing sheet and apply them to the inside of the windows. Press down firmly to ensure no air bubbles or gaps, as paint will bleed into any unmasked areas. If your body doesn't include them, you can create your own using masking tape and a hobby knife, cutting along the window lines.

Custom Masking with Tape or Liquid Mask

For any other design elements – racing stripes, flames, two-tone schemes – you'll need to apply additional masking. Tamiya masking tape is highly recommended for its excellent adhesion and clean removal. For intricate designs, you can lay down tape and cut out your patterns with a sharp hobby knife. For very complex or curved areas, a liquid mask can be painted on, allowed to dry, and then cut with a knife. This offers incredible flexibility but requires more drying time.

Always ensure your masking is firmly pressed down, especially along edges. Any lifted edges will result in fuzzy lines or bleed-through, which is incredibly difficult to fix once the paint is applied.

The Painting Process: Step-by-Step for Polycarbonate

Now for the exciting part! Remember, proper ventilation is crucial. Work in a well-ventilated area, ideally outdoors or in a garage with open doors, and always wear your respirator mask.

1. The Golden Rule: Dark Colours First, Then Light

This is the most crucial difference when painting polycarbonate from the inside compared to traditional external painting. Because you're seeing the paint through the clear plastic, lighter colours will be visually affected by darker colours painted over them. Therefore, you must paint your darkest colours first, then progressively move to lighter shades. For example, if you have a black stripe on a white body, you'd paint the black stripe first, then mask it, then paint the white. If you painted white first and then black, the black would likely show through the white, making it appear grey or dirty.

2. Shake Your Paint Thoroughly

Before each use and between coats, shake your spray can vigorously for at least a minute. This ensures the pigments are evenly mixed, preventing patchy or inconsistent colour application.

3. Apply Light, Even Coats

Resist the urge to lay down a thick, heavy coat. This is a common mistake that leads to runs, drips, and poor adhesion. Instead, apply multiple light, even coats. Hold the can approximately 20-30 cm (8-12 inches) from the body and use smooth, sweeping motions. Overlap each pass slightly to ensure full coverage. It's better to do 3-4 thin coats than one thick one.

4. Allow Adequate Drying Time Between Coats

Patience is a virtue here. Allow each coat to dry to the touch before applying the next. This typically takes 10-15 minutes, depending on humidity and temperature. A hair dryer on a low, cool setting can speed this up, but be careful not to overheat the plastic or paint.

5. Repeat for Each Colour

Following the dark-to-light rule, apply your first darkest colour in light coats. Once dry, carefully remove the masking for that colour, then apply new masking for the next darkest colour, and so on. This iterative process ensures clean lines and prevents colours from bleeding into each other.

6. The Backing Colour

Once all your primary colours are applied and dry, it's time for the backing colour. This is a crucial step often overlooked by beginners. A backing colour serves several purposes: it makes your colours pop by giving them an opaque base, adds durability to the paint job, and prevents any light from shining through your finished shell. The most common backing colours are white (which brightens any colour) or black (which deepens colours and hides imperfections). Apply 2-3 light coats of your chosen backing colour over the entire painted interior surface.

Finishing Touches and Decals

Once your backing colour is completely dry (ideally after several hours or even overnight for full cure), you can proceed with the final steps.

• Remove All Masks: Carefully peel off all masking tape and window masks. Do this slowly and at a shallow angle to avoid lifting paint.
• Remove Outer Protective Film: This is the satisfying moment! Peel off the clear protective film from the exterior of the body shell. Your paint job will instantly appear vibrant and glossy.
• Apply Decals: Most RC bodies come with a decal sheet. Cut out your desired decals and apply them to the *exterior* of the body. Use a soft cloth to smooth them down and remove any air bubbles.
• Mount the Body: Place your newly painted and decaled body onto your RC chassis, securing it with body clips.

Troubleshooting Common Painting Issues

Even experienced painters encounter issues. Here's how to identify and, where possible, prevent them:

• Paint Runs/Drips: Too much paint applied in one go, or coats too thick. Prevention: Apply lighter, thinner coats.
• Fishtails/Uneven Spray: Often caused by inadequate shaking of the can, holding the can too far away, or spraying in a cold environment. Prevention: Shake well, maintain consistent distance, ensure paint is at room temperature.
• Poor Adhesion/Peeling: Usually due to inadequate cleaning of the body (grease, fingerprints) or using non-polycarbonate specific paints. Prevention: Thorough cleaning and using the correct paint type.
• Bleed-Through Under Masks: Masking tape not pressed down firmly enough, or liquid mask not fully dry/thick enough. Prevention: Ensure masks are perfectly sealed.
• "Orange Peel" Texture: Paint drying too quickly (often due to spraying too far away or high temperatures) or paint not atomising properly. Prevention: Spray closer (but not too close), ensure proper temperature and humidity.

ABS vs. Polycarbonate Painting

While both materials are used for RC bodies, their painting methods are fundamentally different. Here's a quick comparison:

Frequently Asked Questions (FAQs)

Q: Can I use regular spray paint on my polycarbonate RC body?

A: Absolutely not! Regular spray paints are designed for rigid surfaces and will crack, peel, and flake off a flexible polycarbonate body very quickly. You must use paints specifically formulated for polycarbonate (e.g., Tamiya PS, Pactra, Pro-Line).

Q: How many coats of paint should I apply?

A: Typically, 2-3 light, even coats of each colour are sufficient for good coverage. For lighter colours or those with less opacity, you might need a fourth. Always finish with 2-3 coats of a backing colour.

Q: How long does the paint take to dry?

A: Drying time between coats is usually 10-15 minutes, depending on temperature and humidity. For the final backing coat, allow several hours, or even overnight, for the paint to fully cure before handling or removing masks to prevent smudging or lifting.

Q: Can I paint the outside of my RC body for special effects?

A: While some experienced modellers might apply very thin, specialised effects (like weathering) to the outside, it is generally not recommended for the main paint job. Any paint applied externally will chip, scratch, and wear off very quickly during normal RC use, ruining the look and durability.

Q: How do I fix a mistake, like a run or bleed-through?

A: Unfortunately, fixing mistakes on polycarbonate is very difficult, often impossible, without damaging the plastic. Unlike external painting where you might sand and re-spray, paint on the inside adheres very strongly. Prevention through careful preparation and technique is key. Sometimes, small imperfections can be hidden with decals or by incorporating them into a new design element.

Q: Do I need a clear coat for polycarbonate paint?

A: No, a clear coat is not needed and generally not recommended for polycarbonate paints. The clear polycarbonate shell itself acts as the clear coat, providing the gloss and protection. Applying an external clear coat would only add another layer that could scratch or dull.

Q: What about chrome or metallic paints?

A: Chrome and metallic polycarbonate paints often require a specific backing colour to achieve their true lustre. For instance, Tamiya's PS-12 Silver is often recommended as a backing for their chrome colours to make them truly shine. Always check the paint manufacturer's recommendations.

Painting an RC polycarbonate body shell is a rewarding process that allows for immense creativity and personal expression. While it requires patience and adherence to specific techniques, especially the crucial 'inside-out' and 'dark-to-light' rules, the results are well worth the effort. With practice, you'll be producing stunning, durable custom finishes that will make your RC car stand out from the crowd. So, grab your paints, take your time, and enjoy bringing your vision to life!

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