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The free-blowing process required a continuously fired furnace. A wad of molten glass was gathered on the end of a long metal pipe. By blowing air through this pipe, the molten "gather" became a bubble of glass that could be manipulated with tools and reheated periodically for easier working. After the application of elements such as base-pedestals, a metal rod ("pontil rod") was thrust onto the bottom of the vessel and the top was cracked off the blow-pipe. Then, with further reheating, the top of the vessel received its final shaping; and elements such as handles and decorative trails were applied from a molten gather. Vessels produced in this way often preserve a scar, or "pontil mark," on the base from the removal of the pontil rod. When complete, the vessel was placed in the annealing chamber of the furnace.