Caneworking in Glassblowing
In glassblowing, the word "cane" means a rod of glass that has color inside. Some are simple, with just one solid color. Others are more detailed, with multiple strands of color arranged in a pattern. The term "caneworking" covers both making the cane and using it during the glassblowing process. When cane is used in the length of a glass piece, it creates detailed stripes, swirls, or spiral patterns in the final form.
Glass artists also use cane to create what’s called murrine. That’s when they cut the cane into thin cross-section slices and add those pieces to hot glass during shaping. These murrine slices show the pattern from the middle of the rod. One well-known style that uses this is called millefiori, which means “a thousand flowers.” In this technique, murrine with flower or star shapes are combined into one piece of blown glass.
This technique goes way back. Caneworking started in southern Italy sometime in the second half of the third century BC. Later, it was pushed even further on the island of Murano, where artists developed the process into a highly detailed art form.
There are several ways to make cane, but they all follow the same basic steps. It starts with a lump of glass that usually already has some kind of color pattern in it. This lump is heated in a furnace, also called a glory hole. Then a metal rod, called a punty, is stuck to each end of the hot glass. The rods are used to stretch the glass out while it’s soft. As it’s pulled, the pattern inside stays the same in cross-section, but the whole rod gets longer and thinner. The glass stretches evenly because the narrow parts cool faster and get stiffer, which keeps the pull smooth.
Glassmakers usually stretch the cane until it’s about the width of a pencil. The final length depends on how big the original lump was. Some canes are just a foot or two, but others can reach fifty feet long. After the cane cools, it’s snapped into smaller pieces, usually around four to six inches long. These pieces can be used by themselves or combined with others to make more detailed cane or complex blown glass designs.
The most basic type of cane is called vetro a fili, which means “glass with threads.” It’s usually made from clear glass with one or more colored threads, often white, running through the center. To make it, the artist heats and shapes a small chunk of colored glass on the end of a punty. Then they dip that into a furnace full of molten clear glass, covering the color with a thick outer layer.
Once they’ve got enough clear glass around the core, the cylinder is shaped and reheated until it’s even. While this is happening, an assistant works on what’s called a post. That’s another punty with a flat bit of clear glass on the end. The assistant sticks the post to the far end of the cylinder, and then both people walk in opposite directions, pulling the cane out between them. They keep pulling until the rod hits the right size and length. The glass cools in a few minutes and then gets cut down into smaller rods, ready for use.
How Complex Canes Are Made from Simple Threads
A basic cane with a single colored thread inside can be used as the starting point for more detailed work. You can take a few of these single-thread canes, bundle them together, and heat them until they fuse into one solid piece. Or you can heat a few and lay them side by side, then pick them up around the edge of a hot cylinder made from clear or colored glass.
This new bundle is treated the same way as a single chunk of colored glass. It gets wrapped in clear glass, shaped, and pulled out to make a new cane. This time, the finished cane has several threads running through it. The center can be clear or one solid color, depending on how the glass is stacked. If you twist the cane while pulling it, the threads form spirals. That version is called vetro a retorti, or twisted glass. Another name for it is zanfirico.
Ballotini: A Variation on the Threaded Cane
There’s also a method called ballotini. This one also uses vetro a fili canes, but they’re placed side by side on a flat surface instead of bundled. A fresh gather of clear glass is rolled over them and then shaped into a cylinder. The threads end up running straight through the middle, lined up along the axis like a kind of fence across the glass.
If this cylinder is twisted and pulled at the same time, you get a cane with a helix pattern that runs across its full width. It’s a more complex version of the basic spiral thread and adds extra movement to the design.
Optic Molds for Patterned Cross-Sections
Another way to make patterned cane is by using optic molds. These are cone-shaped metal molds that are open on both ends and have shapes carved into the inside edge. These shapes might be lobes, points, or star-like designs. When a blob of glass or a blown bubble is pushed into the mold, its outside takes on the mold’s shape.
To create a detailed cross-section, artists build up layers of glass with different colors around a solid core. Each layer can be shaped in an optic mold before adding the next. Since the outer glass is hotter than the inner part, the mold affects only the surface, keeping the inside layers intact. This layering method is often used for making millefiori canes. You can see this in pendants or other pieces made with cross-section discs from several different canes.
Making Cane with a Torch
Flameworkers have their own way of making cane. Instead of pulling big rods from a furnace, they work with a torch and use bead-making or regular flameworking techniques to build up the design layer by layer. This lets them blend colors and shading in a more detailed way. It’s how most murrine portraits are made, where every tiny color change matters.
Filigrano vs. Murrine: Two Ways to Use Cane
When cane is used lengthwise in blown glass, it’s called filigrano, or filigree glass. That’s different from murrine, where the cane is sliced and the design shows in cross-section. There’s also an older term, latticino, but it’s mostly fallen out of use. Today, people usually stick with filigrano and murrine to describe the two main styles.
How Cane Is Added to Blown Glass
One common way to use cane in glassblowing is by laying out the rods on a flat plate, usually steel or ceramic. These canes get heated slowly to keep them from cracking. Once their surfaces begin to melt just enough, they start sticking to each other. The glassblower prepares a blowpipe by adding a collar of hot clear glass at the tip. Then, they press that collar against one end of the warmed cane layout.
The blowpipe is rolled along the row of softened canes, so the cane rods stick to the collar and wrap around the pipe in a neat cylinder. After that, the canes are heated again until they’re soft enough to shape. Using tools like jacks and tweezers, the glassblower seals off the bottom of the cylinder to start forming a bubble. From there, the bubble is inflated and shaped using regular glassblowing steps.
Another method lets the artist pick up cane onto a clear molten bubble. Here, the gaffer starts by blowing a small bubble of hot clear glass. At the same time, an assistant heats a pattern of canes until they fuse together and reach the right temperature. Timing and temperature are key here. The bubble has to be just the right size and just hot enough so that the cane pattern sticks smoothly without trapping air or leaving gaps.
Once the cane is picked up, the bubble gets reheated. The artist can then shape it, roll it on the marver to smooth the surface, or blow it larger. The final form will have the cane pattern sealed inside, often looking like a lacy or striped texture in the glass. If the glassblower twists the piece while shaping, it gives the pattern a spiral motion.
How Reticello Patterns Are Made
The classic reticello look is a tight grid of white lines floating in clear glass. Each tiny square in the grid holds a small air bubble. To create this effect, the artist starts with white-thread vetro a fili canes and forms them into a cylindrical cup shape. As they blow and shape it, they twist the form so the canes follow a spiral pattern. They’re careful not to completely smooth out the ridges inside, which come from the canes themselves.
After finishing the first cup, it’s kept warm in a holding furnace, just below the softening point so it doesn’t slump. Then, the glassblower makes a second cylinder using the same kind of canes, but twisted in the opposite direction. This one also needs to keep some surface ribbing, but on the outside.
When the second piece is ready and at the right size, it’s inserted carefully into the warm cup. The sides can’t touch until the second piece is all the way in. The small air pockets that get trapped between the two ribbed layers are what form the perfect little bubbles at each crossing point.
Once combined, the piece can be inflated and shaped like any other glass object.
People often use the word reticello loosely. It might refer to any crisscross pattern in glass, whether it's made from straight threads (vetro a fili), twisted threads (vetro a retorti), white, colored, with or without bubbles. But the real reticello technique is more precise, with tight spacing, clear structure, and air bubbles placed in every square of the mesh.
