WASHINGTON (AP) — Conservationists at the National Archives are still working to clean up the building’s rotunda area after a pair of apparent environmental protesters on Wednesday dumped reddish powder on the display case housing the original U.S. Constitution.

National Archives administrators granted The Associated Press exclusive access to the site Thursday afternoon as conservationists continue the painstaking work of cleaning the pinkish-red powder from the nooks and crannies of the document’s protective housing. Their tools include everything from vacuum cleaners to cotton swabs to bags full of shredded erasers.

The Archives building’s rotunda, which displays the Constitution and the Declaration of Independence, will remain closed Friday as the cleanup work continues.

Two men dumped the powder onto the horizontal display case around 2:30 p.m. Wednesday.

“We are determined to foment a rebellion,” one man said, in a video posted on social media. “We all deserve clean air, water, food and a livable climate.”

Police then led the pair away, leaving a trail of powder out the door.

In the immediate aftermath, cleanup crews were reluctant to use any sort of water or liquids in the cleanup, especially since they were still unsure of the exact makeup of the powder.

“If you’re working with a dry powder pigment, using water would just turn it into paint,” said Supervisory Conservator Amy Lubick. “Fortunately we’re confident that none of the pigment penetrated the casing.”

The historic document itself is undamaged and locked away. Subsequent analysis revealed that the powder dumped on the case was a mixture of pigment powder and cornstarch. The resulting powder was so fine that an industrial vacuum failed to pick up much of it.

Cleanup crews were “on their hands and knees until midnight” Wednesday and resumed their work Thursday morning working to capture every bit of the powder, said National Program Preservation Officer Stephanie Hornbeck.

Conservationists at the National Archives reached out to colleagues at the National Gallery of Art for tips on specialized cleaning products to use around delicate textiles. They also used decidedly old-school methods such as long cotton swabs and standard-issue erasers.

Hornbeck displayed several bags of shredded eraser material which were piled up and gently rubbed into stained areas, gradually turning from white to pink as they picked up particles of pigment.

Archivist of the United States Colleen Shogan said she’s not sure when the exhibit will be open to the public again, but said she was “thrilled by the amazing work” put in by her conservation staff.

Shogan also said she’s in contact with local law enforcement authorities to ensure the two vandals are fully prosecuted.

“The real impact of this is on the thousands of people who came to Washington, D.C., today and tomorrow to see the Constitution and the Bill of Rights, and won’t be able to,” she said.