Pulling Cane
Cane in glassblowing terms, is a rod of glass that usually has a central core of colored glass. Once cane has been produced, it can be used to make attractive patterns in glass vessels. See cane pickup for a description of how finished cane is actually used. This section will described the process behind the manufacture or the "pulling" of cane.
As with most things in glassblowing, there are a whole bunch of variations on how this can be done, but for this explanation I'll stick to the most vanilla / normal method. First, a chunk of glass color that has been preheated (in a kiln), is picked up on the end of a punty rod.
Glass colour on the end of a punty.
Once the color has been heated further and worked into a smooth cone shape, more clear glass is gathered on top of the colour.
The clear glass is worked evenly over the colour and allowed to cool, and one more gather of clear glass is added so now we have a core of colour with two more gathers of clear glass on top. This results in about two pounds of glass on the end of the punty - say a grapefruit size amount, except more cylindrical.
Clear glass has been gathered over the colour.
While the gaffer (main glassblower) is setting up the colour and adding the clear layers, the assistant is making a "post". That's a small amount of clear glass on the end of another punty rod that has been shaped to have a flat end. In the picture to the right, I'm holding a post while Jeff is shaping the final gather of glass just prior to starting the pull.
In this case I'm the assistant. Glassblowers will usually trade off assisting time with each other, so in this case I'm assisting Jeff - it is way easier to take some pictures as the assistant than while you're the gaffer.
Post in foreground waits for main gather to be ready.
When heat of the main gather is just right, it is dumped on top of the post. The picture is a little blurry as this is a pretty active event and I only got the one stab at it, but I think you get the idea.
Main gather is dumped onto the post.
Now that the mass of glass has punties at both ends, the two punties are pulled apart, and the cane is formed. As the glass is pulled apart, one area is allowed to thin. The thin area cools more quickly than the thicker mass and freezes up. Done just right, the thin "frozen" glass pulls more glass out of the hot, moving "mass" of glass forming a very uniform length of "cane".
The wooden "ladders" on the ground are there to support the cane once the pull is finished. The cross sections are about a foot or so apart, so this pull is probably about 30' long or so. We have the door propped open in case we're a little longer than the space allows and we have to wander out into the street.
Of course, this dramatic moment is why it is called "pulling cane". It is this pull, that only takes about 1 or 2 minutes that is the make or break of the work that leads up to it. Pull too fast and the cane will be too thin and unusable. Pull too slowly and the glass will freeze up when it is still too thick and again is unusable. If the heat is wrong the cane won't be uniform in diameter. It is tricky to get it all just right.
Jeff walks away pulling out a strand of glass cane behind him.
The completed pull is sectioned into manageable lengths and left on the ladder to cool. As the cane is fairly thin (usually 1/4" to 1/2" in diameter) it is thin enough that it can cool without annealing (it doesn't have to be put in the kiln to be coolled down slowly.
The cane is later chopped up into 5-6" sections and used as the basis for a new work. See the cane pickup page for the next step in the life of our cane.
Cane cools on the ladder after being sectioned.