Glassmaking technique: mold-blown glass

(Chinese music) Voiceover: Mold blown glass is made by inflating molten glass in a mold normally made of clay, wood or metal. In the dip mold process, a gather of hot glass is lowered into the mold. As soon as the glass touches the bottom of the dip mold, air is blown into the blow pipe. The grooves inside the mold pattern the glass. However much the bubble is further inflated and shaped, the impressions from the mold will remain in the glass. If the tip of the bubble is held with pincers and the blow pipe is turned, the pattern becomes twisted. Molten glass can also be inflated in a closed mold made of multiple parts. An elongated glass bubble is placed between the open halves of the mold. The mold is tightly closed and air is blown forcefully into the blow pipe. When the glass hardens, the mold is opened and the glass worked free. Closed molds can be used again and again, creating many vessels with the same shape and decoration. (Chinese music)