The company faces difficulties when all paint contracts are cancelled after World War I. The Dreyfus brothers concentrate on the production of acetate fibers. “British Cellulose & Chemical Manufacturing Co.”changes its name to “British Celanese Limited”. Under the guidance of Camille Dreyfus, “The American Cellulose & Chemical Manufacturing Company” (known as “Amcelle” for short), is founded in New York. The company commences building a production facility in Cumberland, Maryland.
The British government invites the Dreyfus brothers to Britain to produce their new airplane paint, along with the intermediate product acetic acid, which was being imported from Canada due to World War I. The British Government patented the process developed by Henri Dreyfus, which lowered the costs of acetic acid anhydride production, leading to the creation of “British Cellulose & Chemical Manufacturing Co.”. Henri Dreyfus manages the company with a workforce of 14,000.
The company “Cellonit” is established. Cellonit contributes greatly to the development of new film materials and finds a sponsor in the Parisian film industrialist Pathé. The product line is diversified to include paints for German airplanes and zeppelins.
Henri Dreyfus, who was working for Hoffmann La Roche at the time, asks the entrepreneur Alexander Clavel-Respinger for financial support and assistance in the production of fireproof celluloid out of cellulose acetate. On December 18, 1912, Clavel, along with Henri and his brother Camille set up “Cellonit Gesellschaft Dreyfus & Co.” in Basle.