Cleaning windows with magnetic sponge
But I don't know which magnets I should order. If they are to weak the sponge will fall of all the time, but I use this monster magnet like this guy the window might get damaged.
Is there someone who got a collection of magnets already (and dirty windows) and want to give it a try?
In my case the window is around 10mm thick + lets say 5-10mm sponge on each side + 3-4 mm thick piece of plywood to distribute the pressure.