After the Hitler's rise to power in 1933 the company gradually began to concentrate on raw materials for the production of explosives. Since 1937 women were employed as workers. After the outbreak of World War II, with the maleworkforce in military service, women were conscripted for work at the company. Since 1940 "Chemische Fabrik Kalk" used approximately 460 forced laborers from Poland and later the Soviet Union. The factory was heavily damaged during the bombing raids which started in 1942. In 1943 the sulfuric acid plant was completely destroyed, a year later almost all of the production came to a standstill. On 6 March 1945 the grandson of the founder, Fritz Vorster Jr. closed the factory after 80 percent of the production facilities had been destroyed. At this time the company had only 100 employees.