Wall arches can be painted as murals on walls or on a regular canvas. The technique used to paint a wall arch is the same regardless of how large the surface to be painted is. Symmetry and perspective are the most important elements to creating a wall arch that looks realistic and balanced. Following some basic steps will ensure the arch has depth and symmetry.
Select the type of arch to be painted. There are many examples of arches to choose from. Some depict a rustic stucco, others are ornate with intricate details carved in stone. Choose the desired arch and gather some pictures to reference when painting.
Prepare the surface to be painted. If the wall arch is being painted on a wall in large scale, prepare the surface by lightly sanding and priming with a latex primer. If a canvas is being used, apply two coats of water-based varnish and lightly sand the surface.
Measure the wall or canvas using a measuring tape. To achieve a symmetrical wall arch, the width and the length of the wall or canvas must be measured. Measure the width and divide the number in half. Draw a mark on the wall at the halfway point. Repeat this with the length. This will mark the centre point of the wall or canvas. All further measurements will be made based on this point.
Draw a large "t" shape on the wall or canvas. Use the centre point as the point at which the "t" crosses. Ensure that all lines are an equal distance from the centre point.
Draw the arch on the wall or canvas. Connect a line from the bottom left of the wall to the end of the left horizontal line of the "t." Repeat this step with the right side. Finish the arch by connecting the lines to the top of the "t" using a curved shape. This ensures that both sides of the arch are equal and centred.
Paint the arch with an acrylic paint. Base coat the arch first, painting it all one colour. Apply two coats, allowing the first coat to dry before the second is applied.
Add highlights and shadows to the wall arch. Mix a small amount of white paint to the base coat colour to create a highlight. Add a small amount of black paint to create a shadow. Paint shadows on the areas of the arch where sunlight would not naturally shine. Paint highlights on the opposite side of the shadows. This will create a three dimensional effect and make the wall arch look more realistic.
Paint details on the wall arch using a small brush. Add faux cracks with a liner brush for a realistic effect. Paint in any ornamental stone details and foliage that might be growing around the arch.
Apply two coats of a water-based varnish and allow to dry according to the manufacturer's specifications.
Always paint in a well-ventilated area.