CHICAGO — Vicki Grantham of the Cremation Society of Illinois slid open a gray metal door. “This is where everything starts,” she said.

Visitors peered into a huge room chilled to 35 degrees and fitted with stacks of long metal shelves on each side.

Homewood, Ill., Mayor Richard Hofeld backed away a few steps. He supports cremation and intends at some point to be a consumer. Still, he found the sight of the cooler where bodies are kept slightly discomfiting. “We know it’s going to happen, but we don’t want to think about it.”

Crematory open houses are unusual, but more operators are starting to offer them, said Barbara Kemmis, executive director of the Cremation Association of North America, an Illinois-based trade group.

“They see it as a way to demystify the process and show families that you can trust the people you’re working with,” she said.

The idea elicits varied reactions. “There are different levels of the ‘ick’ factor,” she said. “Some people are really curious about what happens. Some people don’t want to know.”

On this recent day, Gerald Sullivan, president of the Cremation Society of Illinois, welcomed visitors to not just think about the cremation process, but tour the premises of the family-owned company’s new crematory in Homewood.

Blue balloons marked the turnoff into the complex. A white tent in the parking lot served hot dogs, potato salad and cookies. Staffers like Grantham, the company’s comptroller, gave tours.

“We want this whole thing to be transparent,” said Sullivan. “We like people to have information to make good decisions.”

He took some ribbing over the open house. Several people he invited asked him, “Who wants to see a crematorium?” he said.

But Sullivan, a gregarious man with a sense of humor, thinks a lot of people do.

“Wouldn’t you be interested in seeing something you haven’t seen before and has a little taboo attached?” he said.

Bob and Charlotte Sommerfeld were very interested. The retirees from Orland Park, Ill., are members of the Cremation Society and have prepaid cremation plans.

“We wanted to see what we would be going through individually,” said Charlotte Sommerfeld as she and her husband had lunch in the tent.

They were not squeamish at addressing death. “It’s part of life, really,” Bob said.

At the Cremation Society of Illinois’ open house, visitors in the viewing area looked through a glass wall at the auto loader, a raised track that pushes a container holding a body into the chamber.

In a cremation, families can look through this glass to watch their loved one enter the chamber, Sullivan said; they can turn a key to start the process if they want or if their religious tradition requires it.

The natural gas-powered crematory is fuel efficient, he said. The main chamber reaches 1,600-1,700 degrees.

Staffers took small groups into the brightly-lit area with a roll-up door for company vans bringing in bodies. On one side was the cremulator, a machine that pulverizes bones of the grainy initial remains. Next to that was a station where an operator can pour the cremains into an urn, with a special air system that keeps them from inhaling the dust.

The crematory keeps track of each body with a bar code, Sullivan said. Cremation is increasingly popular; last year 42 percent of Americans who died were cremated.