Tattoo inks consist of pigments combined with a carrier, used in the process of tattooing to create a tattoo in the skin. These inks are also used for permanent makeup, a form of tattoo.
Professional tattoo inks are available in many colors and use a wide variety of pigments, including inorganic pigments, such as carbon black, and synthetic organic pigments, such as brightly colored azo-chemicals. Commercial manufacturers combine pigments with carriers such as ethyl alcohol or distilled water to create liquid inks. They may include preservatives to reduce risk of contamination and other additives to adjust the viscosity of the ink.
Pigments and preservatives in tattoo ink can cause allergic reactions in skin. A portion of pigment applied in a tattoo may migrate to other places in the body, such as lymph nodes. Some common tattoo pigments are chemicals that may cause cancer, but long-term studies would be needed to determine whether these chemicals increase risk of cancer if embedded in the skin.
The European Union has started to prohibit use of certain pigments in tattoo inks out of safety concerns. In the United States, tattoo inks are subject to regulation by the U.S. Food and Drug Administration (FDA), which generally does not investigate commercial inks unless it receives complaints about specific safety issues, such as contamination. The FDA has not specifically approved any pigments for cosmetic tattoos.
Tattooing is an ancient practice, and archeologists have found evidence of tattoos made with soot among people in multiple continents thousands of years ago. Especially since the invention of the electric tattoo machine in the 1890s, tattoo artists have experimented with many chemicals to identify durable pigments that can produce a range of colors without causing bad reactions, often testing inks in their own skin.
Most tattoo inks are intended to be permanent, but there are commercial methods for creating semi-permanent tattoos. There are also traditions of temporary tattoos, including mehndi, applied to the surface of the skin using henna and other dyes.
Components of professional inks Tattoo inks are available in a range of colors that can be thinned or mixed together to produce other colors and shades. Most professional tattoo artists purchase inks pre-made (known as predispersed inks), while some artists mix their own using a dry pigment and a carrier.
In the United States, tattoo ink manufacturers are not required to reveal their ingredients, or to prove that a voluntarily published ingredients list is accurate. Their recipes may be proprietary. Tattoo inks from different manufacturers vary widely in formulation, quality, and safety.
Pigments Tattoo inks are pigments, i.e. very fine powdered colorants, in a water-based liquid. Many of these pigments are also used in artist's paints, textiles, automotive paint, or for printer's ink. Most inks are organic compounds, such as azo dyes and pigments, including monoazo, disazo, indigoid, and oxazine pigments. Some inks also often contain heavy metals. Pigments can be small bits of solids or discrete molecules, such as titanium dioxide or iron oxide. +ColorPigmentsBlackMay contain: Carbon black, usually a main component of black ink Iron oxides, such as magnetite and wustite, along with nickel from impurities in iron oxidesWhiteMay contain: Titanium dioxide Zinc
These have mostly replaced more toxic pigments such as barium sulphate and white lead.RedMay contain: Cadmium sulphide or cadmium selenide Iron oxides or ferric hydrate (red ochre) Mercury sulfide, known as cinnabar and vermilion (although this ingredient has generally been phased out of use) Azo compounds QuinacridoneOrangeCan be considered a shade of red. May contain azo compounds, such as Pigment Orange 13.YellowMay contain: Cadmium sulphide Azo compounds, including monoazo yellow Pigments used for white ink, to brighten the yellow colorGreenMay contain: Cobalt or chromium oxide Pthalocyanine green, known as phthalo green A mix of cobalt and lead chromate (chrome yellow)BlueMay contain: Cobalt, such as cobalt aluminium oxides, known as cobalt blue Copper phthalocyanine, known as phthalo blue NickelPurpleMay contain: Cobalt ManganeseBrownMay contain iron oxides, such as ochre Other elements found in trace amounts in some ink include antimony, arsenic, beryllium, selenium, and aluminium. Titanium dioxide is slightly abrasive and can cause microscopic bits of nickel and chromium to wear off tattoo needles and get into the skin.
Tattoo ink manufacturers often blend metal pigments and/or use lightening agents (such as lead or titanium) to reduce production costs. Tattoo inks contaminated with metal allergens have been known to cause severe allergenic reactions, sometimes years later, when the original ink is not available for testing.
Blacklight ink
Blacklight tattoo ink does not glow in the dark, but reacts to non-visible UV light, producing a visible glow by fluorescence. A typical blacklight ink formula includes microspheres of polymethylmethacrylate (PMMA) containing fluorescent dye. This ink may cause irritation and inflammation, and tattoo artists are divided on whether they consider it safe to use.
Glow in the dark ink Glow-in-the-dark tattoos absorbs and retains light, and then glows in darkened conditions by process of phosphorescence. This uses typically silica encapsulated strontium and calcium aluminates, but sometimes phosphate passivated versions are used. These are considered nontoxic.
Carrier A water-soluble carrier solution flows the water-insoluble pigment from the point of needle insertion (typically using a tattoo machine) into the surrounding epidermis and sometimes dermis. Carriers help keep tattoo ink shelf stable, evenly mixed, and free from pathogens.
Solvents are often ethyl alcohol or distilled water; methanol, propylene glycol, and glycerin are also used, along with denatured alcohol or isopropyl alcohol. When an alcohol is used as part of the carrier base in tattoo ink or to disinfect the skin before application of the tattoo, it increases the skin's permeability, helping to transport more pigment into the skin.
Additives Preservatives such as benzoic acid may be added to tattoo ink to prevent contamination. Some inks contain formaldehyde as a preservative, which is a carcinogen and may cause dermatitis in the skin. Other inks may use benzoisothiazolinone, which is a skin irritant.
To help the carrier serve as a vehicle for delivering pigment, commercial formulations may include wetting agents, pH-regulating chemicals, stabilizers, and thickening agents.
Ink manufacturers may add witch hazel to help the skin heal after the tattooing process.
Vegan inks Some tattoo ink manufacturers produce vegan-friendly inks that do not contain any animal by-products, such as bone char, glycerin, gelatin, and shellac.
Traditional inks
The world's oldest tattoos known to date, those of the Tyrolean Iceman known as Ötzi, were applied 5300 years ago with soot and/or ground charcoal based pigments.
Traditional Ainu tattoos used soot as pigment, which reflected significant beliefs related to the hearth of a home.
In traditional Filipino tattooing, batok, historical examples include inks made from a range of materials: pounded leaves of a native tomato plant mixed with soot and water; pig bile and soot; or soot made by burning resinous wood. Some ink was made by combining soot and sugarcane juice, left to ferment for a short time to develop some alcohol. Recent practices include combining soot with water in a coconut half-shell.
Inuit women have a tradition of kakiniit, tattoos historically made with qulliq lampblack and seal suet. In the 21st century revival of this tradition, practitioners use manufactured tattoo inks.
Japanese horimono practices include tebori tattoos made by hand using sumi ink. This ink is made with soot from burning particular woods, bound with animal glue, and the method of application results in a greenish black color in the skin.
In the Māori tattoo practice, tā moko, tattoo experts have made ink from the ashes of resinous tree parts (such as kauri gum) or caterpillar fungus, mixed with oil from plants.
Homemade inks In amateur "stick and poke" tattoos done for amusement or as a hobby, people often use improvised ink, which adds risk of infection and scarring. Prison tattooing also typically uses improvised ink. Pigments may be made from ballpoint pen ink, hobby ink such as India ink, or soot. Homemade or amateur inks may use Listerine, vodka, or isopropyl alcohol as carriers, with glycerin added to prevent the ink from drying out.
Health effects
Components of tattoo ink may cause allergic reactions in skin, including red, green, yellow and blue pigments. Colored inks, such as red, seem to cause allergic reactions more often than black ink, likely because of small amounts of mercury sulfide in some red pigments. Some yellow pigments contain cadmium sulfide, a light-sensitive compound, and upon exposure to sun this can cause photodermatitis, although rare.
Inks may be contaminated with bacteria, such as Mycobacterium chelonae, which can cause infection in the skin.
Several commonly used ingredients are potential carcinogens – for example, most black inks contain carbon black, which may contain polycyclic aromatic hydrocarbons. Many of the particles used in tattoo inks are less than 100 nanometers in diameter, making it easier for them to penetrate cells and possibly cause cancer. Under UV light, azo pigments may degrade into primary aromatic amines (PAAs), which may be carcinogenic. However, a review article in 2012 said "The number of skin cancers arising in tattoos is seemingly low, and this association has to be considered thus far as coincidental."
After application of a tattoo, a portion of the ink is carried away by blood vessels and the lymphatic system, and some of it may be excreted or stored elsewhere in the body. Tattoo pigments may migrate into lymph nodes, including toxic elements in ink such as chromium. Long-term studies would be needed to determine if pigments in human lymph nodes have harmful effects.
In medical imaging, such as mammography, pigments in lymph nodes may be accidentally interpreted as abnormal results, giving false positive results for cancer. Treatment of cancer may include using blue dye in the body to detect a sentinel lymph node, so existing tattoo pigments in lymph nodes may cause difficulty in identifying and treating sentinel nodes.
In rare cases, a person undergoing a magnetic resonance imaging (MRI) exam may feel temporary discomfort or irritation around tattoos made with iron oxide pigments. Looping or circular patterns may contribute to this effect. Large amounts of ink in the skin, such as in blackout tattoos, may also increase the risk of this side effect.
Regulations European Union The European Union requires tattoo ink makers to indicate any hazardous ingredients on product labels. In 2021, the EU established rules requiring certain green and blue pigments, Blue 15:3 and Green 7, to be phased out of tattoo inks.
United States
In the United States, tattoo inks are subject to regulation by the U.S. Food and Drug Administration (FDA). The inks are regulated as cosmetics (which do not require pre-market approval), and the pigments are regulated as color additives. FDA regulations say that color additives intended for injection must show convincing evidence that they are safe to be injected, in order to be approved for this purpose. The FDA has not yet approved any color additives for injection. The FDA does not generally exercise this regulatory authority because of other higher priorities and insufficient evidence of specific color additives causing safety problems in tattoo ink.