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.
2. Do NOT pressure wash your roof. Read http://roofcoatingscam.com/is-it-safe-to-pressure-wash-a-roof/ to find out why and the damage it can cause. Effectively, the only way to safely clean your roof and the tiles on it is to use a 6 trowel and wire brush and do it manually by hand. Pressure washing can erode the concrete tiles or penetrate through into the felt below and cause flooding in the roof space. 3. Refurbish your roof. After you wash your roof and let it dry, you may want to take additional steps to protect and rejuvenate the surface. 1  Buffing: In time, tile produces a chalky deposit on its surface. 2  This is called efflorescence, and is caused by a natural chemical reaction in manufactured concrete.