The volunteers in the Big Room at Carlsbad Caverns National Park in New Mexico aren’t looking up at the magnificent formations. They focus instead on the trail floor and the cave walls near it. These volunteers are lint pickers. They diligently dab at the rock with tiny synthetic brushes.
The bristles carry a slight charge, so lint that falls from tourists’ clothing sticks. In a yearly, painstaking process, the potentially destructive residue from thousands of tourists is removed to protect the national treasure.
“If we didn’t clean this every year, everything would be a gray, dark, ugly color,” says cave specialist Rod Horrocks, pointing to the trail. He also says the lint could contribute to damage in the caverns.
Scientists believe the caverns formed long ago when water containing sulfuric acid drained away from underground crevices. As it went, it took much of the existing limestone with it, leaving vast hollow spaces. Those spaces are characterized by intricate swirling shapes of remaining limestone and a gypsum by-product. But the soft rock formations are highly soluble. That’s why accumulating lint can cause a problem.
"Water will condense on the lint and this water is aggressive," Horrocks warns. "It'll start dissolving whatever surface it's on."
Most formations in the cave are safe, though. Much of the lint stays on the trail thanks to 18-inch "lint curbs" that line it.
In the past, the park has attempted to solve the lint problem outside the caverns. Workers have tried using blowers to blast loose fibers off visitors before they enter. They have misted down people’s clothing, hoping lint will stay in place if moist. They’ve even tried vacuuming visitors prior to allowing entry. But clothing begins to shed lint regardless around halfway through the hike. There’s no proactive way to stop it, it seems.
The lint is made up not only of tiny bits of clothing fiber, but also strands of hair and skin cells.
The team had hoped to clear the entire main corridor trail of lint this year, but as of late November, it was only a third of the way through.
The park welcomes groups to volunteer to collect lint. It takes only around 30 minutes of training to learn the process and the limitations.
Cleaning up after people is “a daunting task," Horrocks says. "It takes so many people."
