Blau's father was a doctor in the Austro-Hungarian Medical Corps, and very supportive of her desire to become a painter. She took lessons with Schaeffer and Lindenschmit. In 1883, she converted from Judaism to the Evangelical Lutheran Church. Together with her husband Heinrich Lang, they moved to Munich where she taught painting at the Women's Academy of the Münchner Künstlerinnenverein (Munich Women Artists' Association). Blau exhibited her work at the "Palace of Fine Arts" and the 1893 "World's Columbian Exposition" in Chicago. After her husband's death, she spent ten years travelling in Holland and Italy. She helped found the "Wiener Frauenakademie", an art school for women.