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Re: Window Cleaner
without going too technical Gremlin, the dust from the garden hadn't settled it was the minerals in the water. The utility companies add stuff to the water, according to area, to make it what they consider drinkable etc. It is measured in parts per million (ppm) and tap water in the Accy area is around about 40-50 ppm. Leeds, where I do the majority of my work, is between 100-400.
The guys who use pure water to clean windows will treat the water via two different methods to bring it down to zero ppm. This means that the water is pure and contains no elements of iron, calcium etc. It is these additives that are left behind when the water evaporates.
A squeegee guy has to leave the window dry because he uses dirty water to clean the window. The slightest gap from the squeegee sliding around will leave dirty water or soap behind which when dried will leave a streak. The pole guys don't need to leave the window dry because, after rinsing, the window will only have pure water on it. Rain water makes no difference to this because rain water is typically almost pure.
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