As the video explains, the most common types of tattoo machines are the rotary and the coil. Both use bundles of needles to deliver dye into the skin. But, the reason for a tattoo's permanence is slightly more complicated than simply getting that needle to reach the dermis. Once that happens, your body interprets this invasion as a wound, signaling the immune system to begin its repairs. As part of the healing process, macrophages gobble up the dye in an effort to get rid of it. But, many of them end up staying in the dermis with the pigment still inside of them. Pigment particles themselves are also left dangling in the dermis or absorbed by dermal fibroblast cells.
If you’re going to a trusted tattoo artist and parlor — and you follow all their directions for aftercare — your tattooing experience will probably be completely fine. But, sometimes there are nasty, tattoo-related reactions that we don't fully understand. For instance, in a study published earlier this year, the authors describe a patient who developed skin cancer within four months of getting a new tattoo. Weirdly, the cancerous skin alterations were only found in the parts of the tattoo that had been colored with red ink. Although it seems to be an extremely rare reaction, there are a few other documented cases. Mostly, these have been treated as coincidences.
Even if tats aren't your thing, this video gives you a chance to marvel at the awesome, brutal power behind the needles necessary to make those marks perfectly on point. Skip ahead to the 3:10 mark to watch the slow-motion needle in action.