Local company turning IU bell into bicentennial medals

By Michael Reschke

Mike Dillard left the garage door halfway open to stay cool, but beads of sweat ran down the side of his face while he poured the melted remains of a bell from IU’s Student Building into a ceramic mold. A vacuum pump sucked the super-heated metal into the mold, ensuring no air bubbles would ruin the medallions created in honor of Indiana University’s 200th anniversary. Once the castings cooled for a few minutes, Dillard dipped them into a drum of water. The ceramic mold cracked apart, leaving five black IU Bicentennial Medals. He described the color as exquisite.

“I love this project,” Dillard said. “The metal is a little different than what we’re used to using.”

The bell was about 79 percent copper and about 21 percent tin, with less than 1 percent lead, said Kelly Kish, IU’s bicentennial director. It was sawed into pieces and melted with other metals. The result are medals that are about 89 percent copper and about 11 percent tin, with trace amounts of lead. This was done to meet safety requirements for lead content, Kish said. It also helps Dillard do his job.

“If you pour old metal over and over again, it quits turning out,” he said.

A chime consisting of multiple bells was installed in the tower of IU’s Student Building when it was erected in 1906. The bells, weighing hundreds of pounds each, were damaged in a fire in 1990 and placed in storage. Recently, one of those bells was given to Bloomington-based Indiana Metal Craft to create medals that will be given to individuals and organizations that helped broaden IU’s reach.

A 10-person committee reviewed potential medal designs submitted in early 2018. Jeeyea Kim’s design, inspired by maps of aviation routes and ripples from drops of water, was announced as the winning submission Feb. 1. The faculty member at IU’s School of Art, Architecture + Design, worked with Indiana Metal Craft employees to create a mold, known as a die, that would be used to produce the medals.

A hot wax paste is injected into the die with 400 pounds of pressure per square inch, filling every crack and crevice. Five of those wax pieces are placed on something called a sprue base. A stainless steel flask fits into the base, surrounding the wax pieces so they can be submerged in a ceramic slurry. The slurry, which also goes through a vacuum process to remove air bubbles, solidifies after about 15 minutes. Burn out furnaces, heated to about 1,350 degrees, melt the wax, leaving a ceramic mold for the metal.

“The whole process is why it’s called lost-wax casting,” said Ronald Davis, president of Indiana Metal Craft.

It took about a month of experimentation to get the temperature right for this particular casting. Among the considerations were impurities in the metal used to make the bell.

“When you’re making something big and massive, you’re not worried too much about appearance,” Davis said.

It’s a different story when it comes to a commemorative piece with fine details. Several adjustments were made, including how fast Dillard poured the molten metal into ceramic castings.

Dillard is the lost wax production manager. He’s been working at Indiana Metal Craft since 1977. To do his job, he wears flame-retardant shoes, a rust-colored apron and jacket. His gloves look like oven mitts. A plastic face shield protects his eyes and ear plugs drown out the rumble of a gas-fired alloy melting furnace. When Dillard turns it on, green flames form a circle around the top of the furnace. The metal inside is heated to about 1,900 degrees Fahrenheit.

When the medals first come out of the ceramic mold, they’re a dark color Dillard said he’s never seen before. To remove some of the fire scale, tiny beads of glass are shot at the medals in a process Davis called bead blasting. From there, the edges are rounded with a drum sander. Then the medals get a brown conversion coating in the oxidation room. Later, the coating will be buffed off the raised surfaces for contrast. The final step is to apply a clear lacquer coating to prevent tarnishing.

While IU’s Bicentennial Medals are made using the traditional lost-wax casting process, the finer details are as unique as the metal they’re made from.

“We had no experience working with this alloy,” Davis said. “But we’re pretty pleased with the result.”

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