TWIN BRIDGES — Jim Shirk made sure he mixed just the right shade of pink in the sky hovering above the Tobacco Root Mountains on the mural he’s painting on the public library here.

“That’s a color that once you see it, you never forget,” Shirk said this week. “But I didn’t want to overdo it.” The tone of the sky as the sun sets on a summer evening is just one of the details that Shirk painstakingly included in the mural, which adorns the south concrete wall of the Twin Bridges Public Library. There are wrinkles on the shirt of a cowboy, marsh grass along a creek and shadows from the Black Angus cattle.

For Shirk, a 59-year-old retired art teacher from Pennsylvania, the mural encompasses everything he loves about the new home he moved to two years ago.

In addition to scenes of the valley’s rich ranching heritage, the abundant outdoors recreation and wildlife of the valley is also represented. A fly fisherman casts a line down a small stream and a pair of sandhill cranes stands in a meadow.

A ranch entrance made of books titled “Twin Bridges, Public Library, Madison County and Montana” serves as the centerpiece. Stacked around are books titled “Rivers, History, Gold, Cattle and Rocky Mountains” representing the key themes of life in the valley, and indeed throughout the state, he said. And the final book stands open, with a scene of a ranch barn, windmill and irrigation ditch.

It’s all set on a backdrop of the valley as seen from Shirk’s home west of town and meant to invite people to both the area and the library, he said.

“You go to the library to discover, learn and travel,” he said. “You open a book and you can go anyplace.” The mural came about as a way to cover up a wall that was a “disgrace,” said Pat Bradley, a member of the library board. The library received an $8,400 U.S. Department of Agriculture rural development grant and added that to $14,000 that the Friends of the Twin Bridges Library had raised to install new carpets, bathrooms and make other improvements to make it compliant with federal standards for disabled people.

Some money was left over and the board decided to fix up the wall. It had large cracks with construction wire sticking out and gaps from three old windows.

“The neighbors were complaining and saying ‘can’t you do something about that?’ ” Bradley said.

The idea of painting a basic bookshelf came up. The board asked for bids and Shirk presented a proposal with a drawing of his design. His asking price of $2,000 was by far the cheapest, Bradley said, and the library received an excellent deal for the money.

“It was a labor of love because he sure didn’t get what he put into it,” she said. “We’ve been astounded.” Shirk started painting May 3 and has only missed three days since, often putting in 10-hour days. He’s painted throughout his life, but he’d never done a mural since his teaching specialty was sculpting and ceramics. In fact, a three-hour commute and 140 kids to teach left no time for Shirk to do any of his own work, something he’s trying to make up for in retirement.

Shirk said he was a little intimidated at the prospect, but that’s a good thing for an artist.

“If you’re too overconfident, your work suffers,” he said. “You also have to challenge yourself; if you do you can learn.” What he learned were some of the rigors of painting outside, he said. On hot days, the paint dried too fast, while on cold days it wouldn’t dry at all.

The most important consideration for any mural is being careful to plan and make sure the images are accurate to your subject, he said. His biggest fear was painting something that inaccurate to life in the valley, something he said longtime residents have assured he didn’t do.

Throughout the past two months, locals and travelers alike have stopped to chat with Shirk. He said he’s learned some history and also received a lot of compliments as the artwork came to life.

“The people come by and say it’s just wonderful,” he said. “That’s the best pay you can get.” Reporter Nick Gevock may be reached via e-mail at nick.gevock@mtstandard.com.