Chemische Fabrik Kalk (CFK) (lit. Chemical Factory Kalk) was a German chemicals company based in Kalk, a city district of Cologne. The company was founded in 1858 as Chemische Fabrik Vorster & Grüneberg, Cöln by Julius Vorster and Hermann Julius Grüneberg and was renamed to Chemische Fabrik Kalk GmbH in 1892. At times the company was the second-largest German producer of soda ash and was, with almost 2400 employees, one of the largest employers in Cologne. For decades the chimneys and the water tower of the factory dominated the skyline of Cologne-Kalk.