I have posted from time to time about wfp and the salt from the sea.
Each time I was assured that WFP can cope with anything.
I know exactly what you are talking about. 2 years on of using WFP, it does not do a good job right next to the coast. It does not get salt and chalk/sand off windows in the same way that a mop and squeegie does.
Sometimes after a storm, it's almost like you need something abrasive to break though the layer of salt. A brush head and water doesn't touch it. Sea salt and chalk/sand dries like concrete on glass.
The first time you go over the glass with a mop is like you are breaking the ice. It takes a fair bit of elbow grease to break what's on the glass and you can hear the change in the sound and feel the difference as the salt breaks up with a mop. With wfp, all you get is white streaks as the window dries no matter how much water is used. Inland a short way and it's a different story.
Sorry, but that is my experience.
