Hi Everyone, I'm brand new to this and have not cleaned any customers windows yet but am in the process of setting up by getting all the equipment and canvassing for customers. I have bought a facefilt bigboy backpack wfp system and am going to use that until i can afford a full van mounted system. Anyway, I was testing the equipment on my own windows today and noticed that i could not get the sills or frames very clean(at least as clean as I would like them to be if I was paying someone to clean my windows, or clean enough to feel like I have done a good enough job). I was wondering is it ok to powerwash the sills and around the frames to remove bird poop/spider webs/whatever else that stuff is that gets on there, and then use wfp systems to clean the windows, at least for first cleans and has anyone tried this, or is there a better way??. Appreciate all the help, I typed this in a hurry so I apologise if my grammar makes your eyes bleed.