Chrysotype (also known as a chripotype or gold print) is a photographic process invented by John Herschel in 1842. Named from the Greek for "gold", it uses colloidal gold to record images on paper. Herschel's system involved coating paper with ferric citrate, exposing it to the sun in contact with an etching used as mask, then developing the print with a chloroaurate solution. This did not provide continuous-tone photographs. In 2006, 164 years after Herschel's work with gold printing, photographers Liam Lawless and Robert Wolfgang Schramm published a formula based on Herschel's process.