A tattoo artist's skill and equipment can change a tattoo's long term durability. A well trained tattoo artist can bring considerable craftsmanship to the boldest and simplest tattoos. There is a wide variety in the resilience of tattoo inks as well. Tattoo inks consist of simple carbon particles. The carbon base usually comes from burnt wood, cotton, vegetables, India or pen ink and plastic. Professional artists have access to more than 100 different colors. Ink manufacturers are not required to list the composition of their products, so tattoo artists may not know the base of their chosen ink. Nevertheless, plastic based inks are heavily marketed for their relative colorfastness and permanence. Unfortunately, plastic based inks are also more likely to cause allergic reactions.