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Kaitlyn P. Becker ’09 (left) and Martin L. Demaine take a break at the Glass Lab with food and studies.
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On a Sunday afternoon in April, Brendon Edwards plunges a blow pipe into a furnace hot enough to burn flesh from bone. Edwards, an advanced glassblower and instructor, is trying to make a glass bulb at the end of his pipe by rolling the pipe through the pool of clear molten glass.

When the amount of glass is just right, he swivels on his heels and cries “To your left!” as he bears down on the smooth metal tabletop — a marver — that had been directly behind him moments before.

Rolling the glowing glass ball over the marver, Edwards shapes the ball to the proportions necessary to begin the process of making a pumpkin. Edwards is one of six Glass Lab members who together produce about four dozen pumpkins in about four hours.

According to the popular stereotype, MIT people are geeky, artistically disinclined science nerds. But the Glass Lab, where Edwards teaches, is located just below the heart of the Institute, in the basement of the Infinite Corridor in Building 4.

MIT’s Glass Lab was first established in the early 1970s by J. Kim Vandiver PhD ’75, then a graduate student and now a research dean at the Institute. The Department of Materials Science and Engineering originally used the lab for hands-on teaching. In 1986, Professor Michael J. Cima assumed control of the lab and decided to remove its classes from the Course III curriculum.

Artist Page Hazlegrove ran the lab as director from the mid-1980s until 1997, when she unexpectedly passed away. Her assistant at the time, Peter B. Houk, took over the responsibility of running the lab and is the current director.

Houk emphasizes that the sense of discovery is the best part of glass blowing. By teaching outside of the MIT curriculum, students get a pure “desire to explore the material in a hands-on way,” he said in an e-mail.

The lab, currently supervised by DMSE, is completely self-sufficient, with its revenue provided by fundraisers held throughout the year.

On the Sunday afternoon in April, Edwards’s “crew” is preparing for one such fundraiser: October’s Great Glass Pumpkin Patch sale. More than a thousand glass-blown pumpkins will be taken to Kresge Oval and sold off one Saturday. The annual event is a big regional draw, and almost every pumpkin is claimed within the first four hours of the sale’s opening. The proceeds go toward the lab’s maintenance.

Making a glass pumpkin

After Edwards has made his glass ball, he returns to one of the side furnaces, also known as a “glory hole,” to reheat the still glowing glass that hardened while being rolled over the marver.

Seconds later, he brings the ball back to the marver and into aluminum tins of glass shards, called “frit.” Edwards rolls the clear glass through the purple and green frit.

After more reheating, rolling along the marver, and reheating, the glass is ready to enter the “optic mold.” The mold’s round cavity has jagged edges that will give the pumpkin ridges.

Edwards drops the glass-covered tip of his blow pipe into the mold and delivers a short, powerful burst of air through the upper end of the pipe into the inner domain of the glass ball. The outward pressure forces the pliant glass to fit the ridges of the mold. Edwards again plunges the glass into the glory hole.

At this point, the rest of the pumpkin’s shaping is transferred to the care of Michelle M. McGuire, another crew member. McGuire uses a special rubber tube to fit the end of the pipe so that she may continue to blow through it as she rolls the base of the pumpkin within the glory hole.

As the pumpkin reaches its final size, it is removed from the glory hole to be rolled along the raised side bars of one of the two benches in the lab.

McGuire uses the sharp prongs of a pair of “jacks,” a tool shaped like long tweezers with a rounded top, to thin the layer of glass connecting the bottom of the pumpkin to the excess glass around the tip of the blow pipe. The rounded top of the jacks smooths some of the chunkier frit on the surface of the pumpkin.

While the finishing touches are put on the base of the pumpkin, Edwards is busy constructing the stem. An elongated version of the clear glass used for the base is rolled over the marver and then in yellow, green frit. After a quick trip to the glory hole and a dunk in a smaller optic mold, the stem is ready to be attached to the pumpkin’s base.

When McGuire requests a stem, one seems to materialize at her side ready to go. She guides the stem to the top of the pumpkin using the jacks, and Edwards pulls back on his blow pipe as McGuire rolls her blow pipe to stretch the glass an appreciable distance while also twisting the ridges in the stem.

Then Edwards wraps the stretched glass around a copper pipe held by McGuire. Diamond shears are used to cut away the glass connected to Edwards’s blow pipe. McGuire pulls the copper pipe through the glass coils while simultaneously spinning the blow pipe attached to her pumpkin, allowing the stem to nest prettily around the top.

A blow torch is then used to adhere the rapidly cooling coils to the base of the pumpkin. After yet another trip to the glory hole to prevent the pumpkin from cooling too rapidly and cracking, it’s off to a bed of cotton, where the pumpkin nests as it is tapped from the blow pipe.

A second blow torch is used around the small opening where the pumpkin had been attached to the blow pipe to melt any sharp edges. A simple metal spoon smooths over those sharp protrusions.

The pumpkin is quickly transferred to the annealer. It will stay there for about a day as it slowly cools to room temperature. This slow cooling helps to prevent cracking.

Not every pumpkin makes it to the sale in October. Some nearly complete pumpkins are deemed inferior and quickly sentenced to the trash bin. Glassblowers are perfectionists: Even a small crack, or too-thin walls, may doom a pumpkin.

Starting at the beginning

Each semester, about 16 students take beginner glassblowing classes at the lab. Admission is by lottery: The lecture hall 6-120, which seats about 150, is nearly filled to capacity each semester. Many joke that the Glass Lab is harder to get into than MIT.

Brendon Edwards and Katina I. Edwards, instructors of the beginner classes, start one session by demonstrating how to make a paperweight.

Like most things in the lab, the paperweight begins as a clear glass blob at the end of a blow pipe. From there, the students use their creativity to create the interior of the paperweight, which is then covered by a layer of clear glass. Further manipulations create a rounded shape. Only then is the paperweight ready to be released from the pipe.

In another session, students learn to make punties. A punty isn’t much — just a small glass piece at the end of a blow pipe. But the punty is an indispensable tool for a glass blower because it can be used to transfer larger glass pieces between pipes. Proper punty proficiency will greatly reduce the scarring sustained by cups and other items that will be made in later classes.

As each student approaches the marver and begins manipulating a punty, Brendon and Katina offer suggestions: “Bend your knees more.” “Tip the pipe up.”

The instructors can tell the students whether their punty is good by eyeballing the glass. If a punty is not made quite right, students are expected to repeat the process until they could consistently make good punties.

Edwards then creates a glass ball for the students to practice their punty transferring ability. If a student’s punty is too cool, it won’t affix to Edwards’s pipe, and the glass ball will drop to the floor, where it will roll away or shatter on impact with the cement.

Students who have completed the beginner class often continue at an intermediate level, where they may teach beginners and may learn from advanced students or professionals in the field. Intermediate students learn to make more sophisticated items, like bowls.

But the lab instills more than a sense of technical proficiency: For many, it creates a community, too. The lab is a “strong and lasting community of active participants,” Houk said in an e-mail. At any time, about 50 people affiliate themselves with the lab, about 40 students and 10 instructors.

Martin L. Demaine, an advanced glassblower who is an artist-in-residence and visiting scientist at the Computer Science and Artificial Intelligence Lab, drops by during his lunch breaks and watches beginner classes.

Kaitlyn P. Becker ’09 has been blowing glass for a few years. She hangs around the Lab, doing homework and occasionally glancing up to see what is going on over at the work benches.

For Michael L. Stern ’09, a mechanical engineering student and an intermediate glassblower, one of the best parts about glass blowing is “the people.”