Ok another controversial statement. The fastest way to clean glass with a brush is sometimes to hold it in your hand and not on a pole. This is because when close up to the glass at arms length the brush can be swivelled by using your wrist. Your brain allows the universal joint that is your wrist to change the angle at the speed of thought. However for out of hand reach work a pole is needed but not always faster as your own body can restrict the movement when working close to the surface.
When working at height the angle of movement is generally a natural up and down with the whole arm joints acting as the universal joints at the base of the pole, this is where Jiks optimum angle now becomes very important. Getting the brush to splay (and I know splay is not something everyone agrees on) is more difficult. The splay allows more glass coverage with the bent ends of the bristles reaching further and also cleaning with the sides.
At one time I thought that crinkle bristles would be fantastic but found the Salmon hygene range to be too stif to allow splay. Have a look at a Boars head carwash brush or a long bristled paint brush if you want to see splay.
Right, Angles or rightangles
Lets say the bristles on most brushes spread gradually out from the centre at a slight incline of 8 degrees to the stock, with the cntre row at 90 degrees to the stock, this is to allow the edges to splay when dust brushing floors and get in the corners, but a deckbrush needs no splay because it needs to scrub. The handle of the brush is fixed into the stock at angle suitable for floors so that pressure can be applied vertically lets call the stock angle 20 degrees (anyone agree or disagree ? ) but not always ideal for our use because we need to apply pressure against the glass with the pole at say a further 15 degrees. This all becomes even more important when using extreme light poles at height. You may not be able to apply pressure.
So I angle the bristles slightly upwards allowing all the bristles to splay in the same direction flattening onthe glass slightly, then using the upward friction of the bristles only to do the scrubing work, the downward pull generally only squeegeeing the dirt and the water back down the glass.
Whats the angle? I guess 45 degrees.
Hope this all helps. Its not by any means complete any other input, arguments etc. Alex ?
Its great to have someone else thinking and questioning the process through Jikwan, Sir. (and anyone else like Dave I missed out.)