The American Academy of Dermatology distinguishes 5 types of tattoos: Traumatic tattoos, also called "natural tattoos", that result from injuries, especially asphalt from road injuries or pencil lead; Amateur tattoos; Professional tattoos, both via traditional methods and modern tattoo machines; Medical tattoos; Cosmetic tattoos, also known as "permanent makeup".

Traumatic tattoos

According to George Orwell, coal miners could develop characteristic tattoos owing to coal dust getting into wounds. This can also occur with substances like gunpowder. Similarly, a traumatic tattoo occurs when a substance such as asphalt is rubbed into a wound as the result of some kind of accident or trauma. These are particularly difficult to remove as they tend to be spread across several different layers of skin, and scarring or permanent discoloration is almost unavoidable depending on the location. In addition, tattooing of the gingiva from implantation of amalgam particles during dental filling placement and removal is possible and not uncommon. A common example of such accidental tattoos is the result of a deliberate or accidental stabbing with a pencil or pen, leaving graphite or ink beneath the skin.