The number of treatments depend on how heavily inked the tattoo is, the colours used, and the location (tattoos on the distal parts of the body are slower to respond, eg, the wrist). Cover-up tattoos are expected to be slower due to the extra layers of ink.
If the tattoo is multicoloured, then more treatments may be required. Simple blue-black tattoos usually require fewer treatments. Professional tattoos generally require around 12 treatments but this is highly variable from person to person. Some tattoos have required many more than 12 treatments. Fewer treatments are necessary for amateur tattoos. Multicoloured designs usually require more treatments than the simple blue-black tattoos. Treatments are done with at least 6 weeks between. Green and light blue ink are often quite resistant to treatment.