Mud Plaster (Banco)
The mud brick superstructure of a mosque is finished with a layer of mud plaster or banco. The actual mixture used varies considerably, but in addition to local soils, the mixture typically includes much finer organic particles, included finely chopped straw, rice hulls, ash, and even soil from termite mounds. The resulting mixture may be used immediately, or can be fermented over a number of days to increase its cohesion and strength. It is this banco layer that most quickly erodes during seasonal rains, and must be regularly renewed to maintain the structural integrity of the overall building.