Nigel ( NWH) and DJ,regarding isopropanol,your opinions are as different
As `chalk and cheese` I guess.`Squeaks` wether your windows `bead` or `sheet`
Even at 20 foot,how do you know wether that window will dry `spot` free?

?
Ya don`t,it`s impossible.Like Jeff says,it`s faith and experience.What about if
Your in towns and city centres at 3 am doing office blocks at 60 to 80 feet???
Pitch dark,can`t see a thing.There can be masses of bird mess,you don`t know,
Because ya can`t see a thing!! Am I teaching grandma to suck eggs here or what?
Yes Jeff,I am sworn to secrecy,and a secret it will stay.It`s in it`s infancy,I call
It searching for the holy grail…ie. Clean ya windows and turn phobic glass into
Hydraphlic glass.There again as some previous posts have stated.some fella`s
Prefer phobic to hydrophilic…………………….To each his own I guess.
Lewis Doubtfire Gleem Clean ( The Blade Runner )