
Color and depth change the session count a lot, so it is estimated at consultation.
When a very short laser pulse is absorbed by ink particles, a sudden pressure wave breaks them into fragments. Immune cells then clear the fragments so they gradually leave. Picosecond lasers produce a stronger effect than nanosecond ones and are reported to clear in fewer sessions. The number needed varies greatly with ink color and depth.
It takes six to ten sessions at six to eight week intervals. It varies greatly with ink colour and depth, so it is worth estimating at the consultation first. Black absorbs every wavelength and clears well, while coloured inks such as green and yellow absorb only limited wavelengths and need more sessions.