Abstract: A filter cartridge for filtering fluids comprising: a cylindrical porous support tube which is permeable to the fluid to be filtered; at least one layer of boro-silicate glass filter paper being wrapped around the cylindrical support; a porous sleeve including a wall having a longitudinal slit therein to allow wrapping of the sleeve around the filter paper; and a zipper affixed to the wall which closes the slit and maintains the position of the glass filter paper without damage to the paper. Also disclosed is a method for manufacturing a filter cartridge having as a principle filtering element a boro-silicate glass paper which is very fragile and can be seriously degraded by crushing. The method comprises wrapping at least one layer of boro-silicate glass paper around a cylindrical porous support; wrapping a cylindrical porous sleeve including a wall having a longitudinal slit therein around the filter paper to secure and protect the filter paper; and closing the slit by closing a zipper attached to the wall.