September 29, 2008
If You Can’t Stand the Heat
By Tode, Laura
The works of art on the shelves around the furnace room at Billings Bronze look like soft, sugar-coated marshmallow ghosts, hardly the regal sculptures their artists intended.It's taken weeks to get to this stage, the pouring room, where the plaster and sand casts wait to be filled with molten bronze. The forms will start to take shape here, but the sculptures are still a long way from finished.
"When people see a bronze, they really don't appreciate and understand all the steps that went into making it," said Wayne Paulson, who works at Billings Bronze.
Paulson has worked at the foundry, which is owned by his brother Cal Paulson, for the past four years. He knows the entire bronze casting process because each step is critical to the next. But Paulson doesn't usually lend his expertise until the casts arrive for pouring.
"You really don't know what it is," Paulson said of the puffy- looking white molds.
The process starts with an artist's clay sculpture. In the foundry, the sculpture is carefully cut into pieces that can be more easily cast separately. The pieces are covered in silicone to form a flexible plastic mold. The silicone mold is then filled with melted wax to create a thin shell that is a cast of what will eventually be cast in bronze. Every finished bronze is hollow, and getting the wax the right thickness is an art form in itself.
Two foundry workers with an eye for the tiniest details specialize in working the melted wax and rebuilding or defining parts of the artist's rendering that may have been altered in the process. The wax pieces are thin and fragile and demand a light touch.
Once the wax pieces have been touched up, a funnel-shaped opening is added to pour in the melted bronze. Vents, called sprews, are added to allow air to escape when the bronze is poured. The wax pieces are then dipped in plaster and dusted with sand numerous times until a thick white cast is made.
Then they need to go into a 1,800-degree kiln to burn out the wax and cure the plaster before they are filled with bronze. Paulson comes to the process when the casts move from the mold room to the furnace room.
Paulson has done a lot in his life. He spent 22 years in the U.S. Marine Corps, visiting 33 countries. He owned a chain of three Italian restaurants, and most recently worked as the operations manager for a mining company in Phoenix.
His work there include working with high-temperature furnaces used to extract precious metals.
When it was time to retire from the mining industry Paulson got a call from brother asking if he wanted to join him at the foundry. Paulson took the offer and said he's been having the time of his life since.
The expertise he brought with him from the mining industry serves him well when it comes to fine-tuning the two furnaces used to melt bronze. One furnace melts bronze for pouring, and the other larger furnace is used to reclaim bronze scraps. Paulson built the furnace and developed the process used to reclaim the leftover bronze.
Pouring the molten metal into the molds is not a one-man operation. Usually it takes at least three people - two to guide the crucible filled with molten metal over to a sand barrel where the molds sit and another employee to control the pouring. The crucible is about 2,100 degrees and weighs more than 200 pounds. It's not uncommon for the thermometer in the room to read 130 degrees.
"You go through a lot of water and Gatorade," Paulson said.
After cooling, the molds are cut away and can be reused, and pieces of the sculpture are "chased out," meaning they're cleaned and welded back together. Flaws that occur during the casting process might require filling in a divot, or grinding away a bur of bronze. Chasing out the bronzes is Paulson's favorite part of the process, and it requires careful attention to the way the rest of the piece is sculpted. Every welded spot will need to be blended with a tiny grinder and then polished to the same smooth finish.
"You have to keep in mind how the artist does their texture," Paulson said.
After the sculpture is chased out, it should look exactly like the clay original before it goes to the patina room, where it is painted with a corrosive stain that gives bronze sculptures their distinctive color.
"It's really rewarding once you get a piece done," Paulson said.
Copyright Billings Gazette Sep 1, 2008
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