Hawach Scientific Co., Ltd qualitative filter papers are divided into standard grades and wet strengthened grades. Wet strengthened grades are added a small amount of chemical stabilizer on the basis of the standard grades. Wet strengthened grades are with better moisture resistance. Qualitative filter paper ash content is less than 0.1%. Qualitative filter paper covers a wide range of laboratory applications and frequently used for clarifying liquids. Wet Strengthened grade filter paper exhibits excellent compression resistance under high pressure and vacuum laboratory conditions and is not easily damaged.