Wash the barrel thoroughly with soapy water to remove any dust or dirt.

Once the barrel is dry, apply a plastic primer designed to adhere to polyethylene plastic. Follow the instructions for the primer, including safety precautions. Note: Don't skip this step. Primer is important! Paint will not stick to a rain barrel without primer, and house paint primers will not adhere well to rain barrel plastic.

Gently buff the primer surface with fine sandpaper to remove any glossy areas.

Paint the barrel with artist's acrylic paint. Acrylic paint is durable and won't chip or crack as easily as other paints.

Allow several days for the paint to dry completely and apply a clear spray sealant to protect your artwork. Follow the instructions for the spray sealant, including safety precautions. This will protect your work of art from the elements.