Metals electrically interact with each other, to begin a series of interactions. As in metals, some non-metallic materials have electrical properties and participates in the interactions. And carbon is one such material falls in the list of the reactants and the following tin completely. Not only that, but the all-metal electronics lose during these interactions and this is something common between them, while the carbon acquires electronics when interacting with the rest of the metals. This means that the electric interaction is very strong and a good source of energy,. Consists of lead in the pencil of the ordinary graphite (a type of carbon) and China clay (aluminum silicate). The more severe the higher the pen where the proportion of graphite.
We must work to avoid marks or writing in the active metal such as aluminum, which may be used in non-greased in the plane's wing, for example, may cause a fire disaster by plane because of the interaction of carbon with aluminum.
To avoid such problem, the engineer must use a sharp object to put up signs, or a special pigment that does not contain carbon. Because the tool is sharp only scratch the surface of the metal (in the case of aluminum Siltim scratching automatically by the spillover of the oxide layer), while the dye does not transfer electrical interactions.Engineer may have sometimes to cover the entire fuselage protective coating, paint signs upon, and then remove it after the hole all the necessary places.