Wondering how to paint styrofoam? Whether you’re tackling a craft project, decorating your home, or working on a DIY task, painting styrofoam can be a bit tricky. Styrofoam is lightweight and versatile, but its delicate surface requires special care when painting. Certain paints can cause it to melt or become misshapen, so it’s important to choose the right one.
In this guide, we’ll walk you through styrofoam painting techniques, share tips on which paints work best, and highlight some common mistakes to avoid, ensuring you get smooth, professional results every time.
Styrofoam Painting
Styrofoam consists of expanded polystyrene beads, which are lightweight but fragile. It has a porous surface that can absorb liquids quickly, and some paints with solvents can dissolve the material. The trick to painting styrofoam successfully is to use water-based paints and, if necessary, prepare the surface to prevent excessive absorption.
There are two main types of styrofoam:
- Soft and flexible foam, used in crafts and packaging.
- Rigid, high-density foam, often used for insulation and architectural details.
Both types require similar painting methods, but higher-density foam may hold paint more effectively and result in a smoother finish.
Best Paints for Styrofoam
Below are the best types of paint for styrofoam projects:
- Acrylic paints: A popular choice for crafts and decorations due to their vibrant colors and quick drying time.
- Wall and ceiling paints: Great for large styrofoam panels or decorative molding.
- Latex paints: Provide flexibility and excellent coverage, making them suitable for both indoor and outdoor projects.
- Fully acrylic spray paints: Ideal for achieving smooth, even coats, especially on complex shapes.
- Water-based exterior paints: Suitable for outdoor applications, but may leave a slightly rough finish.
- Water-based hobby paints: Easy to work with and great for smaller decorative projects.
- Insulation paints: Perfect for functional applications, especially when styrofoam is used as thermal insulation.
- Water-based effect paints: You can apply water-based effect paints on rigid styrofoam. It will work even better, especially if you use a primer before painting.
Paints to Avoid
- Solvent-based paints – These dissolve styrofoam and create holes or deformations.
- Cellulose and synthetic paints – Cause shrinking or cracking of the material.
- Modified acrylic sprays with solvents – Though they may seem similar to fully acrylic sprays, they can damage the foam. “Related article: oil based stain vs water based.”
How to Paint Styrofoam?
1-Sand the Styrofoam Surface if It is Rough
If the surface of the foam is rough, lightly sand it with 200-220 grit sandpaper to smooth out any imperfections, and wipe away the sanding dust with a dry cloth. This will help you achieve a flawless finish after painting the foam.
2-Apply a Primer
Use a water-based acrylic primer to cover the styrofoam surface. The primer reduces the foam’s absorbency and helps achieve a smooth surface. While optional, we recommend priming the foam for projects that require multiple coats of paint. “Related article: Is primer necessary before paint?”
3-Let the Primer Dry
Wait 5-6 hours for the primer to dry. This step ensures that the paint is not absorbed too quickly and helps the dark-colored foam cover more easily. “Related article: painting over dark color without primer.”
4-Apply the First Coat of Paint
Use a brush or roller to apply the first coat of acrylic or latex paint. For large Styrofoam surfaces, a short-pile roller is a good choice, while a brush is better for painting textured styrofoam.
5-Let the First Coat Dry
Wait at least 5-6 hours for the first coat to dry before applying the second coat. Since styrofoam is painted with water-based paints, the first coat will dry quickly.
6-Apply Additional Coats if Needed
Apply a second or even third coat for optimal coverage. Make sure each coat is completely dry before applying the next. After the final coat has dried, you can apply a water-based varnish to protect the paint on the styrofoam.
Advanced Tips for Painting Styrofoam
- Thinning paint for the first coat: If you don’t want to use a primer on the Styrofoam surface, thin the paint with 15% water for the first coat. This helps prevent the foam from absorbing too much paint.
- Use varnish for durability: To protect the paint on the Styrofoam surface, apply a water-based varnish 24 hours after the final coat. This adds shine and makes the paint more resistant to wear.
- Outdoor use: If your Styrofoam project will be exposed to the elements, choose water-based exterior paints and consider varnishing the surface for extra durability.
Frequently Asked Questions
We have answered the most curious questions about styrofoam painting below. Feel free to comment for other questions.
Can You Use Watercolor on Styrofoam?
Yes, but it may absorb too quickly. Applying a primer first or using multiple layers can improve the result.
Is Acrylic Paint Safe for Styrofoam?
Yes, acrylic paint is one of the best options for styrofoam. It’s available in a wide variety of colors and won’t cause any deformation.
Can You Use Food Coloring on Styrofoam?
While food coloring can work, acrylic paints are more practical and durable for most applications.
What is The Best Primer for Styrofoam?
Acrylic and latex primers are ideal for styrofoam. They improve paint adhesion and create a smoother finish. “Related article: do you need to primer before painting?”
Is it OK to Spray Paint Styrofoam?
Yes, but only with fully acrylic water-based spray paints. Avoid solvent-based spray paints, which can melt the foam.
Can You Paint Styrofoam Without Primer?
Yes, though the foam may absorb the first few coats of paint. Thinning the first layer with water can help, or you can simply apply more coats to build up coverage.
How to Paint Styrofoam Without Melting?
Always use water-based paints and avoid solvent-based products to prevent melting or warping.
Does Acrylic Paint Stay on Styrofoam?
Yes, acrylic paint adheres well to styrofoam. For added durability, you can apply a coat of water-based varnish after the paint dries.
How Do You Prep Styrofoam for Painting?
In most cases, minimal preparation is needed. Light sanding and applying a primer can improve the finish, especially for high-detail projects.
What Kind of Paint do You Use on Styrofoam?
You can paint styrofoam with all types of acrylic, latex and acrylic paints and interior and exterior water-based paints.
How do You Make Styrofoam Smooth and Paintable?
After sanding the styrofoam with 200-220 grit sandpaper, apply a water-based primer.
