How To Seal Acrylic Paint on Plastic: Step-by-Step Guide

Eleven tubes of bright acrylic paints and a squiggle of color for each.

Using acrylic paint on plastic is trickier than on many other surfaces because it’s too smooth to let the paint stick and settle. 

Even if you manage to get that done, you still need to seal your painting to preserve the colors for longer without fading, and that’s where this article comes in handy!

In the following, we’ll show you how to seal acrylic paint on plastic in quick and simple steps in order to give your plastic surfaces a complete makeover.

So without further ado, let’s dive right in!

Supplies Needed

  • Sponge and soapy water
  • Fine grit sandpaper
  • A blower or vacuum cleaner
  • Masking tape (optional for bordering)
  • Plastic primer spray can
  • Acrylic paint spray can
  • A plastic sealant of your choice (we’ve included our top recommendations below!)

Step 1: Make Sure the Surface Is Clean

Painting or sealing acrylic over grime will show bumps and make the paint wear or peel quickly.

For that reason, you should always start your process by cleaning the plastic surface where you’re going to apply paint.

You don’t need any special detergents here since scrubbing the plastic with some room temperature soapy water and a sponge will get the job done.

Once you’re done, rinse off any remaining soap and allow the surface to air dry completely.

Step 2: Sand the Surface Down for Better Paint Absorption

As previously mentioned, the smooth surface of plastic makes it more difficult for the acrylic paint to stick.

To solve that, all you have to do is make the surface a little rougher by using some fine-grit sandpaper. Around 120 to 220 grit would be ideal (try this multipack).

This also comes with the added bonus of ensuring a level surface for better paint and sealant application. Remember, you only need to make the surface slightly rough, so you should apply the sandpaper gently.

Unlike wood, you don’t have to sand in the grain’s direction, so you can sand it in circles or straight lines.

When you’re done, suck up the sanded dust using a vacuum cleaner or a blower or wipe it down with a clean piece of cloth.

Fandeli Sandpaper Sheets - Multipurpose 80,120,...
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Step 3: Border the Painted Area (Optional)

If you’re doing multiple paint colors and you don’t want them to overlap, you should consider bordering the painted area with masking tape. 

Define your work with the tape in order to make sure that you’re covering and exposing the right parts.

Step 4: Apply Primer to Help the Paint Stick

One of the biggest challenges of painting on plastic is getting the paint to stick to its smooth surface, even after roughing it up with sandpaper. The best thing to do here is to apply a primer coat.

In addition to helping the paint stick, a primer will also cover all the imperfections on the plastic surface and give you a clean foundation for consistent colors. 

Hold the spray can at the same distance from the plastic surface (around 1 to 1.5 feet away) throughout the primed surface, and make sure that you spray it evenly in a smooth motion so that it becomes an even layer. 

We recommend primers like Dupli-Color or Rust-Oleum because they provide a smooth finish and allow regular paints to adhere to plastic. They also dry pretty quickly!

Before painting on plastic, you must make sure that the primer coat that you’ve applied earlier is completely dry.

Acrylic paint will to adhere to plastics but especially when you’ve used a plastic primer, so you shouldn’t overlook this step.

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Dupli-Color CP199 Clear Adhesion Promoter Primer -...
  • Improve adhesion of all paints
  • Quick drying clear primer
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Rust-Oleum 209460 Plastic Primer Spray
  • The product is 12oz wht plas primer
  • Easy and simple use kit

Step 5: Start Painting on Plastic

Now that your plastic item or surface is ready for painting, it’s time to use your acrylic paint spray can.

Luckily, you’ll need to use the acrylic spray paint the same way as you’ve used with the primer, so the primer step would be a good practice of how to do this one right. 

Remember to keep the nozzle at a consistent distance from the surface, and keep the spray can moving to keep the paint level.

One good tip here is to apply a very thin layer of paint and allow it to dry completely, and then follow up with multiple coats of thin paint, but always allow every coat to dry first.

This way your finished item will have a consistent color and you’ll be able to control the thickness of the layers and keep them smooth and even. 

Step 6: Apply Proper Sealant on Your Painting

Now that your last coat of paint is dry, it’s time to apply your sealant to preserve the colors and protect them from fading.

Sealants come in a wide range of types that have different properties to suit various tastes and purposes. 

Make sure that you use a clear sealant and decide whether you want a glossy, regular, or matte finish. You can apply the sealant either with a brush or directly from a spray can.

The brush-on method is ideal for saving time and effort on larger surfaces while the spray-on method is perfect for small items and is much easier in general, so you should pick your favorite accordingly.

Luckily, most brands on the market offer all these options in different quantities to suit your needs, but more on that in the following section!

Ideally, a single coat of sealant is good enough for most indoor items, but you can apply more if you’re painting outdoor objects like plastic patio chairs. 

Like always, make sure that each layer of the sealant cures and dries first before applying the next one.

Topcoat Options for Sealing Acrylic Paint on Plastic

As previously mentioned, there are various topcoat options to consider while sealing acrylic paint on plastic items. Let’s have quick look at each one of them:

Acrylic Polymer Resin

Acrylic polymer sealants, also known as acrylic resin varnishes, are the most popular when it comes to acrylic paint. These sealants are made from emulsified water-based polymer resins. 

Acrylic polymer varnishes are quite common because they strike an excellent balance between durability and clarity without sacrificing ease of application.

They’re mainly used indoors but can also be used outdoors in a relatively shaded area with little rain.

Liquitex Professional Varnish

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Liquitex Professional Soluvar Gloss Varnish, 295g...
  • Archival; Removable; Glossy; Transparent
  • Lightweight and dries to a water-resistant, non-yellowing surface

The top recommendation for acrylic resin varnishes  is the professional varnish from Liquitex.

The polymer sealant is available in a wide range of container sizes ranging from 4-fluid-ounce spray cans all the way up to 1 gallon for large projects.

Although they’re not the most durable when it comes to water protection, these sealants provide excellent adherence to acrylic paints. 

The sealant is also available in various types of finishes to suit your requirements. These include deep matte, semi-gloss (satin), gloss, and high gloss finish.

Polycrylic

Polycrylic sealants are also water-based polymer sealants that are made from polyacrylate resin.

They’re known for providing one of the clearest finishes among sealants, which is ideal for indoor display items. They also dry up quickly, so they’re ideal for beginners.

However, you’ll typically need to apply more coats of polyacrylic sealants to overcome their lack of durability.

Minwax Clear Water-Based Protective Polycrylic Sealant 

Minwax 33333000 Polycrylic Protective Finish Spray...
  • PROTECT WOOD SURFACES – Minwax Polycrylic Protective Finish Spray protects even hard to reach...
  • CRYSTAL CLEAR FINISH THAT LASTS – The crystal clear finish offered in this wood protection spray...

Minwax provides polycrylic sealants in a wide range of sizes, including an 11.5 fluid ounce spray can, 1/2 pint, 1 quart, and 1 gallon. 

The sealant is relatively more affordable than Liquitex Varnish while providing a non-yellowing, quick-drying, ultra-clear finish. All that makes it an excellent choice for a beginner!

Polyurethane

Polyurethane sealant, on the other hand, is made of oil-based elastomers.

Being insoluble in water, the paints are excellent for sealing acrylic paint on plastic if you’re going to leave the painted items outdoors.

In other words, you won’t have to worry about rain washing away your paint. However, the only drawback of polyurethane is that it’s not as clear as water-based polymer sealants.

Minwax Fast Drying Protective Polyurethane Sealant

Minwax Fast Drying Polyurethane Protective Wood...
  • PROTECT WOOD SURFACES – Minwax Polyurethane Wood Finish protects interior projects like woodwork,...
  • OIL-BASED DURABLE FINISH – Clear finish provides long-lasting protection and warm beauty to both...

Our recommendation for polyurethane sealants is also from Minwax, which shows the quality of their products.

This polyurethane sealant is extremely durable and can withstand harsh outdoor conditions with long-lasting protection that protects your paint from fading. 

It also dries up pretty quickly and comes in a wide range of finishes and container sizes to match your needs!

Decoupage Medium

Last but not least, you can use a decoupage medium as a sealant for acrylic paint on plastic! Decoupage medium is a diluted form of white glue that adheres well to acrylic paints.

You can also use it with a variety of surfaces, making it extremely convenient for art-project enthusiasts! 

Mod Podge Sealant Glue

Decoupage Kit | Set 8oz Bottles of Mod Podge...
  • SET INCLUDES: (1) 8 oz. Mod Podge Matte, (1) 8 oz Mod Podge Gloss in handy squeeze bottles. No mess!...
  • ADHERES paper, fabric and other porous materials to almost any surface. Protects decoupage, collage,...

Mod Podge is one of the most popular decoupage glues out there. It has medium-level durability and clarity all the while coming at a highly affordable price, making it a great bang for the buck.

It’s also available in both gloss and matte finishes, and you can buy them in many different container sizes for added convenience.

Final Thoughts

This wraps it up for this guide that shows you how to seal acrylic paint on plastic in simple and easy-to-follow steps.

Although the sealing process may take some time and elbow grease to get it done, the end results will always pay off. 

In the end, remember to take your time between different steps, and allow the paint to dry before sealing it for maximum aesthetic quality!

Last update on 2022-09-25 at 07:58 / Affiliate links / Images from Amazon Product Advertising API

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Rich

Rich

I'm a hobby enthusiast with a real love for painting miniatures. I also happen to run this site and write the majority of its content!