What Really Makes Tattoos Permanent?

The reason why your tattoo is permanent boils down to how skin reacts to ink deposits. The skin doesn't actually absorb ink as many previously thought — immune system cells called macrophages "eat the ink" according to NBC News, and pass it on to other cells.

As the needle punctures into this middle layer, which contains tough connective tissue, hair follicles, and sweat glands, according to WebMD, "it causes a wound that alerts the body to begin the inflammatory process, calling immune system cells to the wound site to begin repairing the skin," neuroscientist and mind-body expert Dr. Claudia Aguirre explained during a TED Talk. This process essentially traps the ink under the skin, and therefore causes the tattoo to be permanent.

"We further demonstrated that tattoo pigment particles can undergo successive cycles of capture-release-recapture without any tattoo vanishing," Anna Baranska, of the French research institute INSERM, wrote in a report published in the Journal of Experimental Medicine (via Rockefeller University Press).