One of our long-time window cleaning customers in Bloomfield Hills, MI asked us to pressure wash a really dirty terrace.  We tackled the project and it turned out great!  Notice the difference in these photos.  The brown staining you see occurs when leaves and other plant matter breaks down on the surface and deposits tannic acid.  This is the same phenomenon that makes the water in some rivers and lakes a copper or bronze color. We used  a blended alkaline detergent to break down and neutralize the stains, making them much easier to remove.  Give us a call for you pressure washing needs.  Why waste a whole Saturday fighting grime like this, when you could be out golfing or getting a massage!