The new Sewline Air Erasable Pen has a 0.8mm ceramic roller ball point, and it glides over fabrics without snagging the surface. The ink is a special formula that does not bleed and keeps a sharp edged, fine line. There is a magic to this ink as it will simply vanish into the air within 2-10 days and will not reappear. If you want to remove or alter something you've drawn, the Sewline marking can be simply dabbed off with plain water. Always test this Sewline pen on a fabric sample before marking up your project. Some fabrics contain sizing or other chemicals which may inhibit ink removal. Sewline AIRerasable Fabric Pen.