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.