The controversial inscription repair to the Martin Luther King Jr. Memorial will probably not be complete in time for the 50th anniversary of the 1963 March on Washington, the National Park Service said Monday.

The shrouding and scaffolding around the memorial’s statue of King will be taken down in time for commemorations, and much of the repair has been done, said Park Service spokeswoman Carol Bradley Johnson.

But some finishing work will probably have to be completed after the Aug. 28 anniversary.

A problem over how to “sandblast” the repairs cropped up when it was discovered that a contractor’s insurance did not cover the kind of sandblasting product that the sculptor, Lei Yixin, planned to use.

In addition, a test blast using pulverized walnut shells stained the stone and will have to be chiseled out, Lei’s son, Ke Shi, said, speaking Monday for his father, who does not speak English. Shi said work has stopped on the project.

Exploring the Martin Luther King Jr. memorial

“We’re waiting for the Park Service to have a decision on how we can do the sandblasting,” he said.

“My father wants to sandblast, but for some reason the Park Service cannot give my father the authorization and the tools,” he said.

Shi said his father wanted to use an artificial sand called “black beauty” to blast imperfections out of the repaired stone. He was told that he could not use that material but that he could use walnut shells.

He agreed to try it on a small area but discovered that oil in the shells stained the light-colored stone.

“It soaked in about five millimeters, so it’s pretty deep,” Shi said. “We have to chisel it out. . . . The Park Service told us that the insurance company wouldn’t insure if we used black beauty.”

There was no insurance problem with walnut shells, he said.

He said his father had never used walnut shells before but was “willing to try anything” because the sandblasting is a crucial step in the repairs.

“If he does not do the sandblasting, his work is not finished,” Shi said. “And he cannot leave without it [being] finished. So he was desperate.” Lei is scheduled to depart Washington on Aug. 20.

Ed Jackson Jr., the executive architect on the memorial building project, said black beauty sandblasting was done when the memorial was being created two years ago.

Jackson and Shi also said the Park Service is balking at Lei using a sealant on the repaired stone, as he had done in creating the memorial. Johnson said the Park Service doesn’t use sealants but has not yet made a decision.

The Park Service said it was committed to having the final touches done.

“We have an issue with finishing,” Johnson said, “finishing, as in doing the last touches on it.

“What we may have to do is take the scaffolding down for the 28th and then look at how we can do it in the future,” she said. “We are committed to completing this the way that Master Lei believes it ought to be completed.”

Asked whether the repairs would be finished by Aug. 28, Johnson said, “Probably not.” She added that the insurance problem might be circumvented by having Park Service specialists do the sandblasting under Lei’s supervision. The Park Service had proper insurance.

She said that if the project remained incomplete, most people attending the anniversary celebrations would not notice that work was not finished.

The offending inscription, “I was a drum major for justice, peace and righteousness,” was removed last week. It was one of two inscriptions carved on the memorial’s three-story stone statue of King.

It appeared on the north face of the statue and was designed to pair with an inscription on the south face that reads, “Out of the mountain of despair, a stone of hope.” Those words will not be altered.

The memorial is on the northwest shore of the Tidal Basin, near the World War II Memorial.

The inscription was a paraphrase of a quote from a sermon that King delivered two months before he was assassinated in 1968. “Yes, if you want to say that I was a drum major, say that I was a drum major for justice,” King said, speaking at Atlanta’s Ebenezer Baptist Church.

“Say that I was a drum major for peace. I was a drum major for righteousness,” King said. “And all of the other shallow things will not matter.”

The inscription aroused controversy when a Washington Post editorial assistant, Rachel Manteuffel, wrote an opinion piece pointing out the extent of the abridgment.

After Manteuffel’s piece appeared, poet and author Maya Angelou said the paraphrase made King sound like an “arrogant twit,” and members of King’s family expressed dismay.

The Interior Department originally wanted the inscription to be replaced with the full quotation from King’s speech but then decided to remove it altogether.