In this paper, we present our work on the subtle mechanisms of rupture of a continuous ink-jet submitted to various types of initial disturbances. Several experimental methods such as spectral analysis of signals and digital particle image velocimetry (DPIV) are used to characterize both the evolution of the forced liquid jet from nozzle exit to break-off and the formation of main and satellite drops.The spectral measurements allow to quantify the various non-linear hydrodynamic phenomena for the free surface flow under consideration. The experiments can be used for example to explain the appearance of small droplets at low initial perturbation and/or provide an explanation for a drop formation devoid of satellites when a high initial perturbation is used. Finally, our measurements show that some of the numerical results that have been published recently are only capable of providing qualitative results since the appropriate boundary conditions are not taken into account.Digital particle image velocimetry measurements performed on a forced scaled-up model jet demonstrate that there is a coupling phenomenon between kinematic and surface tension effects. More precisely, we show how near break-off, energy is transferred within the jet. Indeed, the results obtained allow to emphasize that a damping of velocity oscillations coincides with an enhancement of radial perturbations. These results which represent the first known measurements of local velocity within the jet improve our knowledge on jet break-up and should provide a significant breakthrough for an appropriate numerical simulation of the continuous ink-jet problem.