Johann Loetz Witwe was a glass manufacturer in Klostermühle between 1851 and 1947 and one of the most important producers of Art Nouveau glass. Artists such as Franz Hofstötter, Leopold Bauer, Otto Prutschner, Koloman Moser, Josef Hoffmann and Marie Kirschner, who worked with Loetz, made a significant contribution to the quality and variety of the production. Loetz Witwe's vases are known for their purity, bright colors and floral elements.