If skin cells are dying and being replace constantly, why don’t the cells absorbing the ink die after a few years, get sloughed off, and take the ink with it? It seems like the average life of a tatoo ought to be about 7 years, but instead it lasts a lifetime.
I’m curious about this as well - right now, on my left knee, there’s a bluish-black spot from where I accidentally stabbed myself with a pencil. In third grade. (I’m 34.)
Because the ink is below the level of skin that continuously is being sloughed off and replenished.
But still, why don’t they at least sort of dissolve or dissipate over time?
-Kris
(Come to think of it I have seen that some people’s tattoos lose their color over time, and become just black outlines. But why doesn’t the black outline disappear as well?)
Good question.
Tattoos do fade slightly or the ink will spread slightly over time but yes, why are they permanent? Especially when you consider (or I was told anyway) that the ink is water based.
Tattoos do fade.
Actually, cells absorbing ink do die continuously. I seem to recall they have lifetime of something like one month. When they die, new macrophage stumble upon droplet of ink, devour it and stay put for month or so, until his death and then cycle repeat.
Argh, missed edit window and misread OP. Ink droplets stay approximately in the same place - they are deep enough to not wear off, and because of that devouring-dying cycle they don’t move much in other directions.
Because the dermis that the ink is trapped in is much tougher and more fibrous than the epidermis. The ink can migrate a very, very small bit in each direction which will cause a bit of dissipation and fading, but other than that there’s not much of anywhere for the ink to go to, so it stays mostly put.