Colored pencil Colored pencil A colored pencil (US-English), coloured pencil (UK-English, Canada-English), pencil crayon (UK-English, Canada-English), lead or coloured/colouring lead (Newfoundland-English) is an art medium constructed of a narrow, pigmented core encased in a wooden cylindrical case. Unlike graphite and charcoal pencils, colored pencils’ cores are wax- or oil-based and contain varying proportions of pigments, additives, and binding agents. Water-soluble (watercolor) pencils and pastel pencils are also manufactured as well as colored leads for mechanical pencils. Colored pencils vary greatly in terms of quality and usability; concentration of pigments in the core, lightfastness of the pigments, durability of the colored pencil, and
Lead smelting methods are usually used to remove the remaining non-lead components of the mixture, for example the Betterton-Kroll process and the Betts electrolytic process. The non-lead metals are usually sold to other metal processing plants. The refined lead may be made into alloys or directly cast. People who operate or work in such plants are also referred to as smelters. Galena, the most common mineral of lead, is primarily lead sulfide (PbS). The sulfide is oxidized to a sulfite (PbSO) which thermally decomposes into lead oxide and sulfur dioxide gas. (PbO and SO) The sulfur dioxide (like the carbon dioxide in