It is often preferred to dye the yarn wrapped around the bobbin. Because this way, some disadvantages of other painting forms are eliminated. In this application, yarns are wound into cones or sleeves that can be pressurized by metal or plastic. The hives are generally cylindrical. Cylindrical coils give smoother dyeing as they are uniform in diameter. Before the yarn is wrapped, knitted fabric or permeable paper is coated on the outside of the sleeves. This allows the pressure to be distributed more evenly.