How do professional window washers wash windows?

What do they use as a window cleaner?How do professional window washers wash windows?
They can use a couple of different methods. First is to use a squeegee. They have a cleaning solution that's like Windex in a bucket of water and a mop-like cleaning attachment on the end of a stick. They then use this to scrub the window clean. Then then use the squeegee to remove the excess water and use a towel to get whatever drips they can.





Another method, is to use a similar cleaning attachment at the end of a long, telescoping pole. But, the attachment has a supply hose of deionized water going to it. They then scrub the glass with the deionized water and let it air dry. The deionized water does not streak or leave a residue (like water spots) when it dries. So, the window comes out spotless when it's dry.





For spot cleaning, they use industrial spray cans of window cleaning foam. But, the squeegee or deionized water method is the best, since they take all the dirt and any residue off of the glass. Using window cleaning sprays just pushes the dirt and stuff along the glass, which is what causes the streaking.