For the Jerusalem glassblower, the blow pipe was the glass tube itself. Around 50 B.C., however, the use of a separate blowpipe was introduced. The source of this inspiration is uncertain. Most likely, someone took the kind of clay pipe then being used with bellows to drive extra air into iron-smelting furnaces, gathered up a hot chunk of glass on its nozzle, and blew from the other end. The iron blow-pipe of the kind used today was surely introduced only a few years later.
The blow pipes invention had far-reaching consequences. It allowed the craftsman to gather a sizeable chunk of hot glass from a small furnace and expand it into larger, sometimes more complex forms. Many changes in the glassworkers' repertoire soon followed. Casting could be used only for glass vessels with an open formplatters, bowls, and cupswhereas free-blowing could be used both for those and for vessels with a closed form, such as the narrow-necked jugs, bottles, and food storage jars which previously had been the marketplace prerogative of pottery-makers.