The process that peamerfan is referring to is an ink that is considered permanent, but since the ink is encased in microscopic capsules it can be easily removed with a single laser treatement (considered much less painful)if the tattoo owner ever changes his or her mind. The problem is that this ink is said to be a much more expensive process, and it doesn't seem as if people who are getting tattoos would think, "Let me get this more expensive process in case I change my mind someday." If they were thinking this at the time of the tattoo, they probably wouldn't be getting the tattoo.
Well, I do not know "everything" about tattoo inks, but I did read about six months ago about a new ink that can be removed later in life more easily than the present inks can. I do not know if this method has been approved yet for general use. The idea is that each bit of ink is encased in some kind of substance that can be destroyed, I think with a laser. The encasement breaks up and the ink somehow is absorbed in a way that it is no longer visible. This seems like a good solution to the problem that people have when they get older and are no longer enthralled by their tattoos, or when they change significant others and need to remove a name.
The first inks for tattoos were obtained from natural materials and were extremely limited as variety of pigments . Currently, you can use many types of paints and pigments, from inorganic materials, like titanium dioxide and iron oxide, up to carbon black, azo dyes and Acridine, quinoline, phthalocyanine and naphthol derivates, dyes made from ash and other mixtures.
As the current trend for tattoo pigments favors acrilo-nitrile butadiene styrene (ABS plastic), as the huge popularity of pigments brands shows it.
There is always the possibility of having an allergic reaction. They are due to metal salts used in the manufacture of pigments.Though, due to non-allergic substances,the allergies have become increasingly rare.
Most tattoo inks technically aren't inks. They are composed of pigments that are suspended in a carrier solution. Today's pigments primarily are metal salts. However, some pigments are plastics and there are probably some vegetable dyes too. The pigment provides the color of the tattoo. However, there are important health risks associated with tattooing, both from the inherent toxicity of some of the substances involved and unhygienic practices.