For most murals I use top quality acrylic paints. The better quality paints incorporate a much more stable pigment that tends to last and have better adherence properties. For some outdoor murals I may use special sign writers paint if appropriate for particular effects.
Any stable solid surface is suitable as a canvas for mural painting. The primary prerequisite is that the surface be clean and free of any impurities such as oils. An inappropriate surface may be made suitable by any or all of the following:
Scraping away peeling paint or other material,
Firstly for any outdoor mural it is important that the surface be adequately prepared. Also important is that the chosen paint have a high quality pigment base. With all the outdoor murals I produce I use a UV resistant sealer that ensures longevity of the artwork.