Thus it was the interplay of these economic, political, and social factors and forces that led to the scramble for Africa and the frenzied attempts by European commercial, military, and political agents to declare and establish a stake in different parts of the continent through inter-imperialist commercial competition, the declaration of exclusive claims to particular territories for trade, the imposition of tariffs against other European traders, and claims to exclusive control of ...
As general advice: RoofCoatingScam does not recommend regular roof cleaning just for the sake of improving the appearance of the roof. Foot traffic can damage roof tiles so we only recommend roof cleaning/de-mossing when it is absolutely necessary, ie when the moss is preventing water from draining off the roof.
What you can expect from a low pressure clean and treat service is a roof to be moss free for a period of 2-5 years. the variance depends on shading, debris and effectiveness of treatment post cleaning. Some roofs will be moss free for up to 5 years before new spores begin to grow.