Although glass vessels had long been made in China, the production of flat glass was not accomplished until the 19th century. Even in the Imperial glass workshops, set up in Beijing in 1696 under the supervision of the Jesuit Kilian Stumpf, window glass or mirrored glass was not successfully produced. As a result, from the middle of the 18th century onwards, when reverse glass painting was already popular in Europe, sheets of both clear and mirrored glass were sent to Canton from Europe. Chinese artists, who were already expert in painting and calligraphy, took up the practice of painting in oil on glass, tracing the outlines of their designs on the back of the plate and, using a special steel implement, scraping away the mirror backing to reveal glass that could then be painted. Glass paintings were made almost entirely for export, fueled by the mania in Europe for all things Chinese. They most often depicted bucolic landscapes, frequently with Chinese figures at various leisurely pursuits, and once in Europe the best were often placed in elaborate giltwood Chippendale or Chinoiserie frames. 18th century examples represent the best of Chinese glass painting, with elaborate compositions, rich color and fine detail. They are often found in the great country house interiors of the second half of the 18th century, amazing survivals of a luxury trade.