Design of the experimental hut and procedure used for spraying. A. An experimental hut with two rooms was constructed assembling nine different surfaces. B. Surfaces of wood, iron sheet, burnt bricks, limestone blocks and cement plastered walls are shown. C. Surfaces of palm thatch, mud daub and oil paint are shown. D. The substrates were fixed on the walls of the hut and demarcated to guide the spraying movement E. Spraying on the tested surfaces was done using side edges to avoid overlap effect. F. Whatman paper was hinged on wood after being sprayed on tested surfaces.