As a result of his collaboration with the artist Vilhelm Klein, Kähler became interested in obtaining the red lustre glaze known as maiolica which had been produced in Gubbio, Italy, in the 16th century. In 1888 he succeeded, developing the now famous ruby glaze known as Kähler red. The designer Karl Hansen Reistrup (1863–1929) soon joined the enterprise, assisting in the production of finely formed, artistically decorated items, especially vases. Thanks to Reistrup's designs, Kähler's ceramics achieved considerable success both at the Great Nordic Exhibition held in Copenhagen in 1888 and at the Exposition Universelle held the following year in Paris. A number of other artists began to design items for the Kähler factory, including Thorvald Bindesbøll, H. A. Brendekilde, L.A. Ring and Svend Hammershøi. Their contributions further enhanced the firm's international success.