The energy density (fluence), expressed as joules/cm2, is determined prior to each treatment as well as the spot size and repetition rate (hertz). To mitigate pain the preferred method is simply to cool the area before and during treatment with a medical-grade chiller/cooler and to use a topical anesthetic. During the treatment process, the laser beam passes through the skin, targeting the ink resting in a liquid state within. While it is possible to see immediate results, in most cases the fading occurs gradually over the 7–8 week healing period between treatments.