Bold statements in eye-catching bright colours emblazoned in weather resistant paints adorn many park entrances, buildings, and other places where the public can view them from a distance. Painting a mural may be like painting a picture on a larger scale, but the techniques and the art materials will differ. Murals can be prefabricated and hung or hand painted directly onto the surface. Choosing the correct picture, the work surface (called the "substrate") and its preparation, the paints, and the preservatives all factor into mural painting.
Some murals are hung, some are free standing, and others are painted directly on a wall. In choosing the placement of your work, you will need to consider the location and the substrate. The viewer point of reference will determine how much detail must be painted. The closer the viewers can get, the more detail should be included. Murals that get constant sunlight may be subject to paint fade, and are not as easily viewed as those placed in the shade. The choice of the surface that will be painted upon will depend on the characteristics of the substrate and the work conditions. If you are going to paint directly onto a wall, you will need to assess the amount of "tooth" (ability for paint to adhere) and durability of the structure.
If you are using unprimed wood, you should paint at least 2 but better still, 3 coats of primer onto the wood. If you are painting directly onto a wall that has already been painted, you may have to remove the existing paint because, if it were to crumble, your mural would come off, too. Surface preparation ranges from scrubbing with soap and water to sandblasting, depending upon need.
One of the more accepted methods of hand painting a mural outdoors is through use of projection. This allows the artist to view the placement of the picture and its contents and then to trace it onto the surface before he begins to paint. In modern times it has also become popular to attach digitally printed murals to buildings. This method is quick and less expensive than hand painting.
Thick paints, usually acrylics, are most desirable for outdoor murals. Paints that are marketed as artist materials are more easily mixed on a palette and longer lasting than lower viscosity commercial paints, such as outdoor Latex paint.
Careful consideration must be taken before selection of a sealer because it has to be compatible with the paint used on the mural and the substrate. For example, non porous sealer should not be used on brick. Sealers must be applied carefully to a completely dried painting, so as not to produce smudging or a grainy or milky effect. Many mural painters choose not to seal at all.