Derwent Lightfast pencils have been formulated as 100% lightfast, this colored core combats the effects of UVA-radiation and maintains the longevity of colors on permanent display. Derwent Lightfast pencils are oil-based, smooth and creamy with a beautiful laydown of rich color. The thick core gives a dense color application which brings vibrancy to any drawing. Artwork created will remain lightfast for up to 100 years under museum conditions.