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.[67]
A two coil tattoo machine
Some tribal cultures traditionally created tattoos by cutting designs into the skin and rubbing the resulting wound with ink, ashes or other agents; some cultures continue this practice, which may be an adjunct to scarification. Some cultures create tattooed marks by hand-tapping the ink into the skin using sharpened sticks or animal bones (made into needles) with clay formed disks or, in modern times, actual needles.
The most common method of tattooing in modern times is the electric tattoo machine, which inserts ink into the skin via a single needle or a group of needles that are soldered onto a bar, which is attached to an oscillating unit. The unit rapidly and repeatedly drives the needles in and out of the skin, usually 80 to 150 times a second. The needles are single-use needles that come packaged individually.
Tattooing is regulated in many countries because of the associated health risks to client and practitioner, specifically local infections and virus transmission. Disposable plastic aprons and eye protection can be worn depending on the risk of blood or other secretions splashing into the eyes or clothing of the tattooist. Hand hygiene, assessment of risks and appropriate disposal of all sharp objects and materials contaminated with blood are crucial areas. The tattoo artist must wash his or her hands and must also wash the area that will be tattooed. Gloves must be worn at all times and the wound must be wiped frequently with a wet disposable towel of some kind. All equipment must be sterilized in a certified autoclave before and after every use. It is good practice to provide clients with a printed consent form that outlines risks and complications as well as instructions for after care.[68]( Wikipedia)
