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Conservator Anna Funke stands next to the H.L. Hunley at Clemson University's Warren Lasch Conservation Center on June 7, 2017. Marlena Sloss/Staff

If you want to know how the cleanup of the Confederate submarine H.L. Hunley is going, think oven cleaner.

In the simplest form of chemistry explanation, the sub is being subjected to a mixture of sodium hydroxide and a mild electrical current.

The effect is that, when combined, it gradually helps to soften some of the concrete-hard buildup of sand, mud and shells that accumulated inside the sub during the 140 years it was buried off Sullivan's Island so that it can be removed later.

"The equivalent would be oven cleaner," said Michael Scafuri, lead archaeologist, pointing to the caustic nature of the reaction.

Another find officials reported Wednesday: A human tooth.

While most of the remains of the eight men who sailed on the sub's final Feb. 17, 1864, mission were removed and ceremonially buried at Magnolia Cemetery in 2004, a tooth was recently discovered stuck in the concretion at crank handle position Number 3.

It is believed that's where crewman Frank Collins sat.

Scafuri said the tooth loss was "post mortem," meaning that long after the sinking, the tooth came loose during the decomposition process and stuck to the crank handle where it corroded with the iron.

Project restoration members gave a media update showing where the restoration project is so far some 17 years after the Civil War vessel was raised from the waters and taken to Clemson University's Warren Lasch Conservation Center in North Charleston.

While the sub's exterior is mostly cleaned bare and smooth, the upper level of the interior still has scabs of concretion. The crank shaft the crew used to hand power the vessel is also clean, but scientist report finding cloth remnants and loose metal sleeves at some of the crank positions.

The thought is these add-ons helped reduce the likelihood of blisters or chaffed hands.

What's still not known is if the team will truly be able to determine what caused the 40-foot-long by 3½-foot-wide sub to be lost after ramming its explosive black powder charge into the Union blockade ship Housatonic, sinking her in a massive explosion.

The sub never returned to port after the attack that night, seemingly lost until a dive team funded by best-selling author Clive Cussler found her in 1995 buried under 3 feet of sand roughly 1,000 feet away from the wreck of the Housatonic.

Conclusively answering the mystery of what caused the sinking remains elusive — for now.

"To be honest and upfront about it, we will always have an element of uncertainty because until we invent a time machine we're never going to know exactly what happened," Scafuri said.

It could be a series of complicated events, ranging from human error to "something obvious" or something not considered yet, he said.

"Everything is on the table within reason," Scafuri said.

The cleanup work, which is often painstakingly slow, will continue with an undetermined finish time. 

Scafuri said the appearance today, however, means the sub is presented in a more clean and clearer fashion than from the day it was recovered in 2000.

"It looks like a submarine now, as opposed to a corroded artifact," he said. "Basically it looks like a submarine now more than ever."

Reach Schuyler Kropf on politics at 843-937-5551. Follow on Twitter at @skropf47.

Political Editor

Schuyler Kropf is The Post and Courier political editor. He has covered every major political race in South Carolina dating to 1988, including for U.S. Senate, governorship, the Statehouse and Republican and Democratic presidential primaries.