Since 1843, the Old Whaling Church, with its familiar white exterior, six grand columns and regal clock tower, has stood watch over Edgartown’s Main street.

But inside the Greek revival church, built during the town’s whaling heyday, was another feature that architect Frederick Baylies viewed as an integral part of the completed project: trompe l’oeil paintings graced the walls and the ceilings, and the church’s interior architecture was built with these sweeping features in mind.

“As I see it now, the architect and the muralist worked hand in hand,” said Chris Scott, executive director of the Martha’s Vineyard Preservation Trust which owns the church. “At the Whaling Church, the architect knew this mural was going to be painted.”

Old Whaling Church circa 1870. — Courtesy Martha's Vineyard Preservation Trust

Like whaling, though, the murals by German artist Carl Wendte did not stand the test of time, and today their only proof of existence is a circa 1865 photograph of the church. Instead of murals, pale gray walls are the backdrop to town meetings, weddings and Christmas concerts.

But thanks to a single existing photo of the murals, and a collaboration across time between Mr. Wendte and Vineyard muralist Margot Datz, a trompe l’oeil mural that Ms. Datz describes as an “arched portal leading to a backlit antechamber that holds light in it” will be restored to the front of the church, painted in 10 shades of gray.

This week, scaffolding graced the front of the church sanctuary that will allow the church walls to become, as they were 160 years ago, a canvas.

The church was built in 1843, and the mural would have been painted between 1840 and 1850, Mr. Scott said. During that time period, Mr. Wendte painted similar trompe l’oeil murals at churches in Provincetown and Nantucket. “I imagine he went from church to church,” Mr. Scott said.

Mr. Scott said that Mr. Wendte, the father of two young children, died of pneumonia at age 28.

The trompe l’oeil murals at the other churches still exist, and Mr. Scott and Ms. Datz visited those churches and received guidance from those who worked on restoration projects, including paint analysis results and the color palette.

Based on Nantucket and Provincetown, Mr. Scott thinks the Vineyard murals were likely on all the church walls and on the ceiling.

Underneath the church’s pressed tin ceilings, Mr. Scott imagines, “is evidence of what was there.”

Mural will need to be completed in March for Vineyard wedding. — Ray Ewing

It’s left to history to determine when the murals disappeared from the church. Mr. Scott put it this way: “I have not met anyone who remembers the mural being there,” with members of the Edgartown United Methodist church in their 70s and 80s saying they did not recall the artwork.

But there are some theories as to why it went by the wayside. Paints of that period were often made of organic materials, like fish oils and milk. “They didn’t last,” Mr. Scott said, and “were intended to be redone periodically.”

And by the Civil War, whaling was also on its way out, Mr. Scott said, with whaling captains selling their fleets to serve as blockades. “So very rapidly the Vineyard and Nantucket went from being huge economic centers to almost being afterthoughts,” he said. Quickly, the town lost the resources to have the mural touched up.

But there was one photo, circa 1865, that shows the trompe l’oeil murals on the back wall, along with original furnishings that are still around, like an altar, chairs and whale oil light fixtures.

After seeing the photo about 15 years ago, Mr. Scott thought it would be nice to recreate the murals. But with other, more pressing needs —roofs to fix and buildings to restore — Mr. Scott waited for the right time to take on mural restoration.

That time came, with $25,000 in Community Preservation funding and $25,000 from a private donor financing the project. And in the fall, Ms. Datz (to whom Mr. Scott had shown the photo years ago) was selected for the project.

Though Ms. Datz has been a muralist for 32 years, this project was a first. “This is new for me,” she said Thursday, standing among the scaffolding inside the church. “I’ve never had a large-scale mural that was monochromatic.”

Margot Datz. — Ray Ewing

“Bow to stern, I’m replicating to the best of my ability Carl Wendte’s original work, but there’s a lot of artist’s intuition that I needed to employ,” she said. “There’s only one photo that I’m drawing intense visual information from.” At points, because of the quality of the photograph, she had to figure out Mr. Wendte’s intentions based on his work elsewhere.

Working in variations of gray “sure has made me use my left hemisphere more,” Ms. Datz said. “It’s very intellectual, a much more intellectual process than I tend to employ.”

Ms. Datz created gridded sketches of the mural, and then rendered it on canvas, in color, at one-fifth size.

But she expects “there’s still that very intuitive, organic aspect of what happens when working on the wall.”

Next week, Ms. Datz will start with gridding the wall, and then transcribing her rendering, in chalk, into the grid. After that, the paints will come out, and “it’s then somewhat paint by numbers.”

The project will proceed with a very Vineyard timeline: a wedding is scheduled at the church in the third week of March.

For Ms. Datz, the project also brings a sense of kinship with Mr. Wendte. “When any artist paints in the style of another artist, you can’t help but feel something emotional,” she said. “It’s a very empathetic experience.”

“It’s sad such a promising, hardworking artist died at 28,” she continued. “I think it’s a tragedy. I like to think of this as bringing back to life the value of his short life.”

And the creation of what once was also helps her see the people of Edgartown in a new light. “I imagine salty, stoic, rustic individuals, when really it seems to me now they were kind of cutting-edge, they were abreast with architectural trends, world travelers.

“Maybe the Vineyard back in the whaling days was really rather hip.”