Was challenged by this awning that had 8 plus years of growth that was caked on. The customer was in the process of selling his multi-million dollar home and to say the least the awning stuck out. After a test of 12.5% SH to test for colorfastness I hit it with a 2.5% mix. I knew that it could proably take more but I didn't want to risk surrounding area. It took some elbow grease, (not available at Home Depot. A friends wfie went looking for some after he suggested using some to get something opened), but I think the pics say it all. The client stated he was very skeptical that I would be able to clean it and couldn't say enough. Now he just needs to talk me up at the Country Club.