Tattooing involves the placement of pigment into the skin's dermis, the layer of dermal tissue underlying the epidermis. After initial injection, pigment is dispersed throughout a homogenized damaged layer down through the epidermis and upper dermis, in both of which the presence of foreign material activates the immune system's phagocytes to engulf the pigment particles. As healing proceeds, the damaged epidermis flakes away (eliminating surface pigment) while deeper in the skin granulation tissue forms, which is later converted to connective tissue by collagen growth. This mends the upper dermis, where pigment remains trapped within successive generations of macrophages, ultimately concentrating in a layer just below the dermis/epidermis boundary. Its presence there is stable, but in the long term (decades) the pigment tends to migrate deeper into the dermis, accounting for the degraded detail of old tattoos.
Some organizations have proposed rules banning sleeves among their members; the United States Marine Corps prohibited Marines from getting arm- or leg-sleeve tattoos after April 1, 2007. Those with sleeves already are protected under a grandfather clause. Nevertheless, tattoo sleeves have become so popular that several clothing companies have produced apparel that simulates the look of tattoo sleeves using transparent mesh fabric printed with tattoo designs.
Don’t expect to get a huge tattoo, or series of them, in just one sitting. They just take too long. Gualteros has some clients who fly in from overseas, and who then spend a few solid days getting big-scale tattoos completed. But that’s a special case. “Usually it’ll happen over more time,” he says. “It could take months, it could take years. Usually, you leave 3-4 weeks between appointments and a sleeve can require anywhere from 8-10 sessions.”
The word tattoo, or tattow in the 18th century, is a loanword from the Samoan word tatau, meaning "to strike". The Oxford English Dictionary gives the etymology of tattoo as "In 18th c. tattaow, tattow. From Polynesian (Samoan, Tahitian, Tongan, etc.) tatau. In Marquesan, tatu." Before the importation of the Polynesian word, the practice of tattooing had been described in the West as painting, scarring or staining.