Ink.

When you get a tattoo, are you actually putting ink into your skin? Or is it something else all together?
Actually Manufactures of inks don't have to release the contents of the ink at all. And there are many professionals that mix their own inks and pigments. Pigments are a material that changes the color of light it reflects.
So actually most tattoo inks aren't technically inks. They are pigments that are mostly made out of metal salts, but some are made of plastics and there are probably some vegetable dyes too. All the pigment does is provide the color of your tattoo. The purpose of the pigment is to color and to keep the color evenly mixed. It also helps to provide ease of application.

The problem with these 'inks' is when it comes to removing them the process is very painful and costly. Most people that have had to have a tattoo removed say that the process of it being taken off was more painful then getting the tattoo in the first place, so now they offer you an anesthetic if you wish to have one. Many people still try to go without one but give in eventually.
Now scientists are trying to come up with new inks that will either disappear after so much time, or ones that will be easier to remove and much less painful.
Though they have been trying for years now they have only come up with a few prototypes.
The only down side is that it would be more expensive.

So is it worth it? Paying EVEN more money for a tattoo that will either disappear or easily be taken off?