Presumably they're just spraying the walls in something like that Neverwet spray (https://www.youtube.com/watch?v=DZrjXSsfxMQ https://www.youtube.com/watch?v=DZ

Presumably they're just spraying the walls in something like that Neverwet spray (https://www.youtube.com/watch?v=DZrjXSsfxMQ https://www.youtube.com/watch?v=DZrjXSsfxMQ). I wonder if they realize that it breaks down in sunlight and won't work after a few weeks.