Skin is the largest organ of the human body, and covers approximately 20 square feet. The skin protects against exposure to bacteria, temperature extremes, toxins, trauma, and ultraviolet (UV) radiation. Skin controls the loss of insensible body fluids, acts as surveillance for the immune system, and aids in sensory perception and thermoregulation. Your skin is comprised of two layers, the epidermis and the dermis. In order to understand how to safely tattoo different types of skin, let’s begin by discussing the first layer of skin.
The surface layer of the skin, the epidermis, is responsible for your skin color through the presence of melanocytes. Sweat glands, sebaceous glands, and hair follicles originate in the epidermis and travel down into the dermis. While we are born with our skin, it continually changes as we age and are exposed to different environmental factors. The epidermal layer completely sheds old skin cells every 14-28 days and gets replaced by new cells. Skin thickness is determined by a person’s age, sex, and the anatomic location. Males usually have thicker skin than females in all anatomic locations. Skin is generally thin in childhood, but gradually thickens until an adult reaches 40-50 years old. As we age, our skin begins to thin again and lose elasticity. Skin is usually thinnest around the eyelids (0.05mm) and thickest on the palms of the hands and soles of the feet (1.5mm). The epidermis does not contain blood vessels, it relies on the dermis below to supply nutrients and eliminate waste.
The dermis is thicker (0.3mm-3mm) and more complex, serving to support and sustain the epidermis above. There are two layers of the dermis, the papillary dermis and reticular dermis. The superficial papillary dermis consists of a thin layer of connective tissue that contains capillaries, elastic and reticular fibers, and collagen. Elastic and reticular fibers of the skin combine with collagen to create a mesh framework. The deeper reticular dermis is made of thicker connective tissue and contains larger blood and lymphatic vessels, and nerve endings. Lymphatic vessels carry lymph, a fluid containing white blood cells, back to the cardiovascular system through the lymph nodes to eliminate any bacteria it encounters along the way. A gel-like substance containing hyaluronic acid surrounds the dermal cells. Hyaluronic acid is a substance produced by the body that retains water within the connective tissues to keep the skin moist. Beneath the dermis is a layer of subcutaneous adipose (fat) tissue that also serves to cushion the skin.
Now that we have discussed the basic structure of the epidermis and dermis, let’s cover tattoo-specific skin considerations. First, let’s discuss the glands within the epidermis further. Sweat glands are present on the surface of the skin except along the vermillion border of the lips. Sebaceous glands are most concentrated and largest in the face and scalp. Sebaceous glands secrete sebum, a wax-like oil, that lubricates the skin to protect against friction and make it impervious to water. Over-production of sebum can also contribute to oily, acne-prone skin. Be sure never to tattoo over a blemish since the pore is pushing sebum and dirt out of the cell and it will not heal retaining pigment and add unnecessary trauma. It is also best practice not to tattoo over a mole since it can be an indicator of skin cancer you do not want to disrupt. Depending on its color, size, and shape, it may not accept or age well with tattoo pigmentation.
Hair follicles form in the epidermis and dermis, and can differ depending on the person’s race. Caucasian hair grows obliquely to the skin surface, while black persons hair follicles point parallel to the skin surface. Asian persons hair points vertically from the skin surface, and produce very straight hairs. These anatomic considerations are important when working with clients that have alopecia, a condition that causes bald spots, and more severely, complete hair loss all over the body. The base of the hair bulb may go as deep in the dermis as the subcutaneous fat. If so, these hairs have the potential to grow back if a deep cut occurs.
There are important considerations for tattooing skin with age-related changes. As we age, our skin thins, becomes more fragile, lax, and wrinkled. Wrinkles usually occur vertically and horizontally along contraction lines (the forehead, nose, and mouth), where we express a smile and frown. Exposure to sun can accelerate these age-related changes by causing dyspigmentation, premature wrinkling, and spider veins. UV-A exposure causes inflammation that breaks down collagen, while UV-B exposure contributes to DNA mutations (cancer). Smoking is another preventable environmental factor that can cause premature skin aging and wrinkles. A client’s medication and skin care regimen should be discussed prior to a initiating a cosmetic tattoo procedure. A client on antibiotics will not retain ink evenly in the skin since the cells are being told to push out foreign materials, whether it is bacteria or ink. Clients with a recent chemical peel, fillers or Botox should also postpone any facial tattoo procedures for at least four weeks. Remind the client that retinols or anti-aging creams will also increase skin cell turnover and decrease ink retention of their new tattoo.
And, seriously, don't forget the sunscreen...after your fresh ink has healed!