Spray Painting Your Model Truck with Aerosol Cans?

First and foremost, it's essential to understand that there are two major differences between radio-controlled cars with a Lexan (transparent flexible) body and those with an ABS (hard plastic colored) body. Both require a completely different painting method and distinct types of paint.

In the previous edition, we've already covered everything about painting Lexan bodies. Now, let’s dive deep into the painting of hard plastic models (ABS, Styrene) commonly used for Model trucks, as well as some radio-controlled cars that use ABS bodies. ABS/hard plastic is usually white or black in color, but you'll quickly recognize the difference by the fact that it's "hard," as opposed to Lexan, which is flexible and can deform, which is not the intention with hard plastic.

Painting a Hard Plastic Model

Preparation is key, and this is perhaps even more the case when it comes to painting your model. Ensure you have a spacious and clean environment. The last thing you want is dust in your paintwork. Many people opt for outdoor painting; if you do, be cautious not to have trees and tall plants nearby, particularly in the spring and summer, as they can often release a yellow layer of dust that could significantly spoil your paintwork.

Step 1: Cleaning and Preparing Your Model

For an optimal outcome, it's crucial that the body is thoroughly clean before you begin masking. There are specialized paint cleaners available for the best result. However, old-fashioned dish soap still works well too (without fragrances or additives!). After washing, it is very important to dry the model with a lint-free cloth. You don't want to leave any dust particles on the part you're going to paint.

After cleaning the model, you can fill in any imperfections with putty, but always do this on a clean model so as not to rub dirt into the object you're spraying. After puttying and sanding, clean the model again to ensure no residue is left. Be aware that not all putties are fully water-resistant, and make sure your putty is completely cured. Moisture in your putty is the last thing you want.

Once you've perfected your model, it's time to truly prepare it. For good paint adhesion, it's important not just to clean the surface but to roughen it up a bit. This can be easily done with a Scotchbrite scouring pad. After roughening up the surface, clean the model once more and you can start masking and then spraying the model.

Step 2: Applying Primer

For effective spraying, it's important that the can is at room temperature or a bit warmer. A common trick is to place the spray cans in lukewarm water (about 40 degrees Celsius) to slightly increase the pressure and make the spray effect more consistent. Of course, shaking the spray can continually is crucial to evenly distribute the paint within since you don’t want any splatters.

When spraying, it’s vital that your environment is clean and that it's not raining. Even if you spray indoors, the humidity from outside can affect your paint. While Tamiya paints are less sensitive to this, it’s best to spray on a dry day without mist. The temperature should be between 15 and 25 degrees Celsius for the best result.

We always start by applying a primer. Primer serves two functions: it improves the adhesion of the actual paint color to your model and it also provides a neutral base color so you don’t have differences in color if your base plastic has multiple colors. That's why you find primer in various base colors (white, light gray, gray, brown, pink). Depending on your final color, you choose the correct color primer.

  • White: For light colors (white, light blue, light green, etc.)
  • Light gray: For medium dark colors but also colors that are difficult to cover (yellow, orange)
  • Gray: For dark colors (black, dark blue, dark green, etc.)
  • Brown: For dark colors with red/brown tints
  • Pink: For bright red colors

Apply the primer in thin, even layers until your model has an even color. Hold the spray can about 20-30cm away (see can specifications for brands other than Tamiya), applying the paint with a sideways motion. Start spraying just before you are over the model and stop only after you've passed it. This ensures even coverage, including the edges. Between layers, let the paint dry for about 30 minutes. You can primarily tell if the paint is dry if it’s no longer showing wet spots; then wait at least another 15 minutes before applying the next layer. Spraying thick layers will also directly increase the drying time!

If you still see imperfections, now is the time to sand your model again to achieve a really neat result. Do this with a waterproof sandpaper grain of 400 - 600. This allows you to correct without immediately sanding everything away. After sanding, clean the model again and apply a new layer of primer until you are satisfied with the result.

Once the primer is completely covering, we can proceed to actually spray your model and optionally mask off the lines. With thicker aerosol paints like Motip or actual car paints, it's advisable to sand between layers with a grain of 1000 - 1500 to roughen the paint. Tamiya paints do not require this and are also much thinner, ensuring that the details of your model are preserved. However, if you start sanding these, you'll quickly pass through the paint layer.

Step 3: Masking Your Model

Unlike Lexan bodies, hard plastic models generally consist of multiple parts. If this is your first model to spray, don't make it difficult for yourself and start with a single base color. If you do want to work with lines, then mount the model so that the lines can run across the various parts. Pay special attention to leaving as few greasy fingerprints as possible since this will have a direct effect on your spray work (fingerprints/ poor adhesion/ stains). Unlike Lexan bodies, you simply spray hard plastic bodies from the outside, although it can sometimes be wise to mask the inside to limit overspray.

For masking the model, use good quality tape that doesn't leave adhesive residues. Both Tamiya and Revell have very good and, especially, fine masking tape. The cheap painter's tape from the hardware store is often not a good idea as this can quickly leave adhesive residues on your model.

When spraying multiple colors, it’s important to first spray the light colors and then the dark ones. This way, you prevent having to apply a lot of paint to achieve a good effect.

Step 4: Actually Spraying Your Model

Have you masked everything properly? No air bubbles under the tape edges or upstanding edges? Then we can begin. As we already said, always work from dark to light. Otherwise, the dark paint will show through the lighter color in your paintwork.

With primer, we already gave you the tip to make smooth sideways movements, beginning to spray before you're above the model and only stopping after you've passed it. With the color lacquer, this is even more important. If you start too late, you'll get a dark spot where the lacquer starts, and if you stop too early, the end of your model won't be completely covered in color. So, pay close attention to the spraying distance of 20-30cm, but more importantly, maintain an even path of spray.

Just like with the primer, it's advisable to warm up the spray cans a bit for a constant pressure. This makes spraying easier and results in a better outcome. You can apply the actual paint colors one by one but continue to use thin layers for a good result. Spraying too thickly causes drips or blotches in your paintwork, and this can ruin your spraying work very quickly.

Just like with the primer, when using car paints it's best to roughen the surface a bit between each layer. However, you do not do this for your final coat of paint. If you are using multiple colors or fine lines, it's advisable not to sand in between.

Tip! If you are using metallic colors or colors with a special effect.

Step 5: Time for the Real Shine (Clear Coat)

Now that your model is truly fully in color, it's time to really let it shine! For this, we use a clear coat layer. You can also choose to apply a matte or satin clear coat depending on the wishes you have for your model. Using a clear coat is always recommended. If your model is sprayed in solid colors without metallic effects, you can decide to leave out the clear coat, but for the protection of the model, it’s still better to do it.

To achieve a good deep gloss layer, we must now work with thicker layers as opposed to the previous paint layers. The trick is to find a balance between a coat thick enough for a deep shine but not so thick that it runs, causing drips. It’s better to spray slightly too thin than just too thick! If the shine isn't 100% after spraying, you can always polish it or apply an additional coat of clear lacquer. Removing a drip is a lot more annoying work.

Common Mistakes Oops

Of course, things can also go wrong during spraying, but fortunately, many causes can be quickly explained and are good learning moments for your next model. If it's only the paint that didn't succeed, you can consider using a so-called paint killer. This removes the old paint from your body, but the result is highly dependent on the paint and the body itself, so a good result in cleaning is certainly not guaranteed!

Not Cleaned Properly

Perhaps the most common mistake is not cleaning the model properly. This can lead to various problems. Common problems are stains/ fingerprints in the paint or craters in the paint. The latter can come from two things. Often, you see a black dot in the middle, and there is dirt left on your model. Another common problem is silicon. You then get a clean little crater, often several on your model. This is a very annoying problem because removing silicon takes a lot of time and patience. So, be careful that you don't work with hand creams or other lubricants in the vicinity of your model!

Too Humid or Sprayed Too Thick

If it's too humid, the paint will not cure properly, the drying time becomes too long, which usually results in a white haze in the paint. We often see this especially in the clear coat layer of the model but can also occur earlier. With metallic paints, you'll see that the metallic will float, and the metal particles will come to lie together, making for a messy glitter effect.

Sanding Marks or Dents in the Paint

Preparation of your model is most important; sanding marks that you still see in your primer will not disappear with spraying. So, make sure your base coat is really sleek; this determines the end result of your model.

Paint Crept Under the Tape

If the tape is not applied properly, the paint will soon want to creep underneath. Applying it is therefore a careful job but ensures your end result. A trick applied after masking is to first spray the old color again and then only the new color; this way, the old color can fill the small imperfections, and it will be much less noticeable.

Craquelure Effect or Cracks in the Paint

This usually happens for two reasons: the most common is that the undercoat was not completely cured. Especially when using several brands of paint together, this is always a very big risk. Our advice is, therefore, to use only one brand of paint. The second is that the paint was sprayed over each other too quickly, so the undercoat had not fully evaporated. The only solution is to strip the model and start over.