Things You'll Need
Newspaper
Painter's tape
Latex or acrylic primer
Disposable plates
Paintbrush
Acrylic paint
Plastic cups
Polyurethane sealer or decoupage medium
Foam brush
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Styrofoam is notoriously difficult to paint if the wrong type of paint is used or the foam isn't coated with a primer first. Some types of paints and spray-paints may chip quickly off after drying or damage the foam. Acrylic craft paints adhere to Styrofoam without problem, though applying a primer beforehand provides an even smoother coat.
Step 1
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Cover the work surface in newspaper. Set the Styrofoam atop the newspaper.
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Step 2
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Cover any areas of the foam that you do not wish to paint, such as the sides on a flat block, with painter's tape.
Step 3
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Squirt or pour some acrylic or latex primer onto a disposable plate. Prime the Styrofoam by applying a smooth coat with a paintbrush. Allow the primer to dry completely. Apply a second coat if the foam is still visible through the primer, and then allow that coat to dry as well.
Step 4
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Squirt a bit of acrylic paint into a disposable plate. Paint the Styrofoam with a paintbrush using smooth, even strokes. After the first coat dries, apply a second if the primer is still visible through the paint, allowing it to dry completely between coats.
Step 5
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Paint additional details on the foam, if desired, using artist's brushes and a second color of acrylic paint.
Step 6
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Seal the project by applying a coat of a polyurethane sealer or decoupage medium with a foam brush to help protect the paint.
Tip
To use spray-paint on Styrofoam, select a paint specially designed for Styrofoam products. Apply the paint in a well-ventilated area. Spray-paint goes on thinner than paint on a brush, so the original foam texture may still be visible through the paint.
If you don't mind a hole in the Styrofoam, a skewer or toothpick pressed into one end creates a handle by which to hold the project while painting. Toothpicks may be used to create a tripod to hold a painted object off the table; simply stick the toothpicks through the bottom of the foam in a triangular formation.
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