in fig3 it comprises a color space 16 which is completely filled with color material e g liquid and through which the optical fiber 1 is drawn on both sides the color chamber is provided with seals or packings 17 18 respectively having holes through them which are so dimensioned that the optical fiber 1 can just pass through them without excessive friction these seals or packings 17 18 consist for instance of teflon they have a bore which is minimally larger than the diameter of the optical fiber they may also consist of felt or other material above the color space 16 there is a storage container 19 for the color material which provides assurance that sufficient color will always be present in the color space 16 a valve 19a is provided in the channel between the color space 16 and the storage container 19 the color chamber 6 can be fastened to a support 21 by means of a screw 20 in fig4 the swing system 10 for the application of the ring shaped markings 11 onto the surface of the optical fiber 1 comprises a mechanically excited oscillator 22 and a nozzle 23 from the end of which a jet of.