According to the patent for permanent marker ink, the colorant in the ink is affixed to a writing surface by the addition of n-propanol, a pyrrolidone, a tryglyceride and a terpene phenolic resin. Additional copolymers, surfactants and extra water can also be added to achieve the right consistency.
Most modern permanent markers contain xylene, toluene and urethane resin. These ingredients allow inks to adhere to a variety of surfaces and produce a deep color and durable finish. However, they are all toxic in large quantities; therefore, it is important to ensure that permanent markers are not used by young children or in confined spaces for long periods of time.
Despite the name, permanent marker ink does not last forever. While permanent ink does not rub off or flake from most surfaces, direct sunlight and other extreme weather conditions are likely to cause fading over time. The porosity of the surface used, as well as its location and exposure to the elements, will affect the durability of the marks. Some solvents also dissolve permanent marker ink, including those found in some non-permanent markers. This is why coloring in with a non-permanent marker over the affected areas is sometimes suggested as a method or removing unwanted permanent marker traces from a whiteboard or other erasable surface.