Paper linen leather like with the pores easy penetration to be impregnated using oil wax or other anti-permeability materials. Seldom used in general valve.

• 纸、麻、牛皮之类，有毛细孔，易渗透，使用时须浸渍油、蜡或其他防渗透材料。一般阀门很少采用。