How to Paint Murals on Pine

Paint indoor or outdoor murals on pine or plywood sheets.

A mural painted directly on to a plaster wall is subject to expansion and contraction under different temperatures, and may crack or peel over time. A mural painted on pine is less vulnerable, but constructing a false wall in front of an existing wall is not a viable option for many hobby muralists. Fortunately, there is a solution: attach inexpensive pine boards or plywood sheets onto a plaster wall, then paint the mural on the wood instead. Pine pressure-treated with chemical preservatives, such as cromated copper arsenate or copper azole, is rot- and insect-resistant and suitable for outdoor murals; untreated pine is best for indoor mural projects.

Things You'll Need

• Pine plywood or boards
• Stud sensor
• Wood screws
• Palm sander
• Medium-grit sandpaper
• Tack cloth
• Wood sealer
• Airless paint sprayer
• Shellac-based aerosol primer
• Acrylic gel medium
• Palette knife
• Trowel
• Acrylic gesso
• Paint stirrer
• Wide, flat paintbrush
• Pencil
• Acrylic matte medium
• Painters tape
• Paint roller
• Roller cover
• Extendible handle
• Outdoor acrylic paints
• Paint pan
• Dish soap
• Detailed brushes
• Removable acrylic varnish

Instructions

1. Find the wall studs with the stud sensor. Hold the pine in place at the wall. Screw the pine to wall at the studs using the electric drill and the wood screws. Repeat as needed to cover the wall with pine.

2. Sand the surface of the pine with the palm sander and medium-grit sandpaper. Wipe free of sawdust by using the tack cloth, a piece of fabric infused with a sticky material that picks up loose particles without leaving a residue.

3. Apply wood preservative to freshly pressure-treated pine. Fill the airless paint sprayer with wood preservative. Stand 6 inches from the pine, holding the nozzle of the sprayer in one hand. Squeeze the trigger and spray on the wood in sections until it is shiny. Wait two months to allow the wood grain to expand and release moisture before applying paint. Omit this step if painting indoors.

4. Spray the shellac-based aerosol primer over each individual knot in the pine. Let the sealer dry for two hours, then apply a second coat to each knot. Pine knots ooze resin, which bleeds through paint if not sealed properly.

5. Fill in cracks and depressions in the wood with gel medium applied with the palette knife. Let dry for one hour. Trowel a thin layer of gel medium evenly over the entire pine surface to create a smooth base for the mural. Let dry for a minimum of 24 hours, or until the medium turns translucent.

6. Stir the bucket of acrylic gesso with the paint stirrer. Acrylic gesso is a flexible and durable water-based paint ground made of calcium carbonate and acrylic polymer medium. Paint gesso over the pine in horizontal strokes, using the wide paintbrush. Let this layer dry for 24 hours, then apply a second layer in vertical strokes and let dry for 24 hours. Semipermeable acrylic gesso releases water vapors trapped in the wood and will not peel off under humid conditions, unlike oil-based gesso.

7. Draw the mural design on the wood in pencil. Fill the airless paint sprayer with liquid acrylic matte medium and spray evenly over the pencil lines to prevent it from mixing with the mural paint. Let dry for two hours.

8. Apply painter's tape around the borders of one mural color. Attach the paint roller and cover to the extendible handle. Open the paint and pour into the paint pan. Saturate the roller and roll on to the mural without painting outside the lines. Remove the wet roller cover, then clean it with water and dish soap. Wash the paint pan. Let the paint dry for two hours. Remove the tape from the mural, then apply fresh tape around the borders of the adjacent areas. Assemble the roller, cover and handle; pour the next color into a clean paint pan, then roll on to the mural. Repeat this process to paint the entire mural. Hand-paint details last with the detail brushes.

Tips & Warnings

• Paint the mural from the top down to minimize drips. Apply two layers of removable acrylic varnish over outdoor mural using the airless sprayer, to protect it from sunlight, dirt and pollution.

• Exercise caution while using the palm sander to avoid abrasion injuries. Open windows when applying the shellac-based primer to avoid excess exposure to the toxic fumes.

References

• The Getty Conservation Institute; "Mural Paints: Current and Future Formulations"; Mark Golden; 2003
• Danny Lipford; Homeowner's Guide to Paint Primer; Jerri Farris
• "The Complete Book of Decorative Paint Techniques"; Annie Sloan, Kate Gwynn; 1989