our company treats the polyester felt, polypropylene felt, anti-static felt, and Aramid felt with the active fluoride. Each type of felt has obtained the ideal water and oil repellent effect. Not only the result achieves the national standard, but also the original appearances are all well kept. After treatment, those filter material can form the molecular barrier around the fiber, which may prevent water and dirt attaching and leaking. Compared with the common filter material, it has the water and oil repellent character; moreover, it also has the anti-cohesiveness and easiness for cake peeling off. This product is especially for southern places of moist and rainy.