Major brands are experiencing brand loyalty due to the growing popularity of the brand as a collectable. Prominent names with a loyal following that have moved into this market in recent years include the likes of Coca-Cola and Heinz. Mediums used to promote brands vary, but might include ceramics or glass for example. The 'porcelain sign', for example, is a vintage advertising medium of the late 19th and early 20th centuries. Approaching the Art Nouveau period, companies saw porcelain as a material that was durable and weather resistant. Be it porcelain or tin, Coca-Cola or a sign promoting Motor Oil, metal signs are very collectable 'advertising' and increasingly sought-after.