Tattoo inks are available in a range of colors which can be thinned or mixed together to produce other colors and shades. Tattoo inks come in nearly unlimited variations, the most popular being red, green, yellow, blue, and white, which is used as a tint (source). Most tattoo inks technically aren't inks at all but rather a combination of pigments that are suspended in a carrier solution. Early tattoo inks were obtained directly from nature and were extremely limited in pigment variety. Minerals,
vegetable dyes, plastics, and metallic salts are all substances that have been used to create tattoo inks. Tattoo ink manufacturers and sometimes tattoo artists hardly know the ingredients of tattoo inks. Most people are probably not aware that the large majority of tattoo inks are based on metals.
Good quality tattoo inks will create bright colorful tattoos while also having the versatility to thin into washes or gradients of color. Not all tattoo inks have the same ingredients and in addition to this discrepancy, companies producing tattoo inks are not required to publish their ingredients. Because different tattoo inks break down at different rates, not all colors fade at the same speed.

For your information tattoo inks and pigments are not regulated or checked by the administration of food and drugs department of the united states. To-date, the food and drug administration does not yet regulate tattoo inks. You must speak to the tattoo artist and get some advice on allergic reactions by tattoo inks on your skin. Allergic reactions to tattoo inks are very uncommon but usually an allergic reaction would show up with a shade of red ink. Allergic reactions to tattoo inks have been reported, but is very rare. You may be surprised to find out that the most common allergic reactions from tattoo inks occur from using organic inks. Additionally, if you have sensitive skin you may want to investigate the ingredients used in tattoo inks, pigments, and ointments. So ask your tattoo artist what brand (or brands) of tattoo inks they use. They are also developing tattoo inks that will fade away on a predetermined schedule without the need for any laser treatments at all.