On 13 December 1879 the Polaun company bought the Neudorf glassworks near Gablonz, expanded and adapted its furnace to use coal gas rather than a wood-burning kiln. In 1879, the Polaun company operated 11 wood gas or coal gas furnaces and a total of 76 pots in the Iser Mountains. In 1880, the six works in Polaun, Wurzelsdorf, Neudorf, Maxdorf and Klein Iser melted over 5,000 tons of glass. Jewellery accounted for the largest amount (2,100 tons), followed by perfume bottles (2,000 tons) and hollow glass (900 tons). In 1881, Wilhelm Riedel designed a glassworks in Stefansruh, close to Polaun. For this project the Riedel family decided to fully utilise the railroad tracks they had built five years previously to transport the coal required to heat the glass furnaces. The factories in Wurzeldorf and Neudorf were closed, the glassmakers were transferred to the new built Stefansruh. In 1882 the two coal gas-burning furnaces in Stefansruh began to produce glass rods.