About  Cotton string wound water  filter cartridge: The Yarn/String Wound/String Woven Filter Cartridge uses 100% pure material,contains no wetting agents, additives.  Each micron rate has its string pattern to ensure the filtration effect.  The Yarn Filter Cartridge has a better dirt-holding capability than general PP Melt Blown/Spun Filter Cartridge.   Material of strings is pure PP or Absorbent cotton.  Material of Cores is pure PP or SS301,SS304.  We do not use recycled material to make the strings and cores.  We manufacture from spinning to string winding, then to the whole filter cartridge.   Absorbent cotton type with SS core can bear 80-120C-degree temperature, and bear strong acid and alkali.   The super-pure grade contains no Silicon, Fluorescence agent and oil, specially for high-level electronic plating industry.   We make the core ourselves.  We provide the whole piece core from 10inch to 40 inch.  The whole piece core has better strength and resistance of pressure than the normal connected core spliced by 5inch or 10inch.