Derwent's Lightfast coloured pencil is their premium pencil, available in a huge range of rich, vibrant colours. Professional quality pencils, each of which has attained a lightfast level of either LF1 or LF2, which means that they are considered fully compliant with the ASTM 6901 and Blue Wool Scale ISO 105 standards. The oil-based core is resistant to prolonged colour change, ensuring museum-stored artwork stays as vivid after 100 years as it did when it was first created. The smooth, creamy laydown of opaque colour is compatible with oil mediums, and produces a paint-like effect when dissolved. Note that this may affect lightfastness. Strong point for ease of sharpening; ideal for detailed drawings and defining negative space. Round wood casing with a light lacquer. End-dipped with the core colour and stamped with 'Made in Britain' and 'Derwent Lightfast'.