Caneworking is a glassblowing technique that is used to add intricate patterns and stripes to vessels or other blown glass objects. Cane refers to rods of glass with color; these rods can be simple, containing a single color, or they can be complex and contain many strands of multiple colors in pattern.
Every cane begins by the glassblower gathering or preparing a punty/pontil with colored glass. Then molten clear glass is 'gathered' over the color by dipping the punty in a furnace containing clear glass. After the desired amount of clear glass is surrounding the color, this cylinder of hot glass is then shaped, cooled and heated until uniform in shape and temperature. Simultaneously an assistant prepares a 'post' which is another punty with a small platform of clear glass on the end. The hot cylinder of glass is now connected to the post, and gaffer and assistant walk with each punty, stretching the glass into a long rod. The molten glass cylinder is pulled and twisted into a long cane, which cools and solidifies within minutes. The cane is then cut into small sections. This makes simple 'filigree' cane—one color encased in clear glass.
More complicated cane can be made by laying patterns of short lengths of filigree cane (4-6") on a plate made of steel or ceramic, fusing them, then picking them up on a mass of molten clear glass. The cane is melted into the mass and re-pulled; often twisting as the cane is stretched. This creates various types of complex cane pictured below and often referred to in Italian as zanfirico, ballotini or laticcino, depending upon the pattern.
One way glassblowers incorporate cane into their work is to line up cane on a steel or ceramic plate and heat them slowly to avoid cracking. When the surfaces of the canes just begin to melt, the canes adhere to each other. The tip of a glassblowing pipe (blowpipe) is covered with a 'collar' of clear molten glass, and touched to one corner of the aligned canes. The tip of the blowpipe is then made to roll along the bottom of the canes, to which they stick. The canes are now aligned cylindrically around the edge of the blowpipe. They are heated further until soft enough to shape. The cylinder of canes is sealed at the bottom with jacks and tweezers, to form the beginning of a bubble. The bubble is then blown using traditional glassblowing techniques.
Cane can also be incorporated in larger blown glass work by picking it up on a bubble of molten clear glass. This technique involves the glassblower (or 'gaffer') creating a bubble from molten clear glass while an assistant heats the pattern of cane. When the cane design is fused and at the correct temperature and the bubble is exactly the correct size and temperature, the bubble is rolled over the cane pattern, which sticks to the hot glass. The bubble must be the exact size and temperature for the pattern to cover it fully without any gaps or trapping bubbles. This advanced glassblowing technique is common in Italian glass and is employed by a number of other glass artists as well.