What does the black surrounding a humidifier filter do?
I think you are talking about the black pre filter material. It lets static cling attract dirt and dust. Its stops larger microscopic pieces of dust and air particulates from entering the intake of the unit. It’s another step in keeping the inside of the unit a bit cleaner, keeping out dirt and dust making the filters last longer, and run cleaner and more efficiently. If its a nylon type material and not paper you can rinse them in running water before each use, let dry and reuse. This really saves you from replacing the internal filter that can be pricey.
