What’s in tattoo inks?
Tattoo inks are solutions comprised of a carrier and a colorant. The carrier is the fluid that is used to transport the colorant to the application location. It may contain glycerin, water, isopropyl alcohol, and witch hazel.
Tattoo colorants are typically pigments — intensely colored compounds that can reflect light in the visible region of the light spectrum — as opposed to dyes, which require a physical or chemical interaction to be anchored into place. In other words, dyes must react with the surface of the skin to develop their color and stay in place. Conversely, pigments provide color without needing a chemical reaction, and are held in place by intermolecular or physical forces.
Historically, pigments used in tattoo inks derived from mineral or geological sources to produce certain colors and hues. For example, carbon (carbon black) and iron oxide were used to produce a black ink. Cinnabar, a mercury sulfide compound, was used to produce red hues. Cadmium compounds, such as “cadmium red (CdSe)” or “cadmium yellow (CdS or CdZnS),” were used to produce shades of red, orange, and yellow.
For the last 20 years, ink manufacturers have moved away from primarily mineral-based pigments to organic ones. Over 80% of the colorants used today are carbon-based, and approximately 60% of these organic pigments are azo pigments. About 30% of the pigments and dyes are approved for cosmetic use, while a number of others were originally developed for industrial applications, like paints or textiles.
Tattoo inks also include a number of additives, such as surfactants, binding agents, fillers, and preservatives. Many of these additives are employed to keep the pigments in a uniform suspension to avoid microorganism growth in the product after opening.