Study Provides Cleanup Ideas for Gateway Arch


ST. LOUIS (AP) – The Gateway Arch gradually loses some of its silvery sheen as various forces – from salt to body oils to graffiti – wreak havoc on the stainless steel monument to the westward expansion and a symbol of Saint-Louis.

Now, a group of national nonprofits and conservation advocates are suggesting ways for the National Park Service to start cleaning the shiny skin of the Ark, the St. Louis Post-Dispatch reported.

“This is fantastic information to have,” said Pam Sanfilippo, museum services program manager for Gateway Arch National Park. “Planning for the future needs of the park will certainly be at the forefront of our minds. “

The park service investigated arch corrosion over a decade ago and completed a report in 2006 on the matter. But in 2015, after further study – and tests involving people rappelling down the sides of the arch for the first time in its history, to collect samples – park officials said it didn’t was “not feasible” to continue with a complete cleaning of the structure.

In 2018, however, several outside organizations, including the Los Angeles Art Preservation nonprofit, the Getty Foundation, and the Springfield, Illinois-based Association for Preservation Technology, had launched their own survey on the conservation of the Ark. The agencies completed their report last August. Arch officials obtained copies in December and held a videoconference on the results in February.

The Ark has not been fully cleaned for a short time after its completion. After its keystone was installed in the fall of 1965, “the final cleaning, repairing and polishing” was done by hand, according to the new report. This cleaning process took a full year and created some of its own visual inconsistencies: where the stabilizing struts had been placed during construction needed special attention, for example.

The 269-page report documented preservation strategies the park department could use to “clean up, possibly recondition and generally conserve” the stainless steel surface of the structure.

The study examined the potential use of such a variety of means as drones, lasers and rappelling, in addition to the more conventional use of cleaning agents. Even bullet residue sample kits were used to gather information about the skin of the Ark.

The report draws on a handful of previous studies carried out between 2006 and 2015. The various analyzes detail the list of threats that pose challenges to the structure.

At ground level, things like de-icing salt caused “surface corrosion,” the report says. Above, studies have shown that air pollutants tarnish the upper reaches of the Ark. And “many visual anomalies” are marks left by the monument’s original construction, in which cranes and machinery had to climb and anchor the structure as work progressed.

Sweat, body oils and graffiti – especially harmful when etched into stainless steel – pose a risk of serious damage “if left unchecked,” the report said.

“These are just things you wouldn’t think of, but they can add up over 56 years,” said Sanfilippo, summing up the many issues facing the outside of L’Arche. “You might think, ‘Doesn’t the rain just wash away? ” Not necessarily.”

Cleaning techniques examined in the report included the use of lasers, a combination of pressurized water, steam, and dry ice, and manual polishing with chemical cleaning agents from Astro Pak, a California-based company.

Even for those who participated in the study and interacted with the park service, there is no indication that the park service plans to clean up the ark anytime soon.

“We are not holding our breath for this decision to be made,” said Mary Cheng, spokesperson for Astro Pak.

She said the company came away feeling there wasn’t a great urgency to tackle the challenges of the monument’s corrosion, and suggested the park department might even be willing to wait years for that to happen. technological improvements present solutions through lasers, robotics or other advancements.

And while there is a desire to combat the “premature aging” of the Ark, Cheng said some parties are reluctant to reverse the natural weathering of the Ark.

These people “want to keep it as organic as possible,” she said. “That’s the impression we got.”

The report notes, however, that corrosion problems could worsen over time or with drastic changes in the atmosphere.

Despite the forces at play on the Ark, Sanfilippo said: “It’s still amazing how reflective it is.”

But if the structure is ultimately cleaned, the difference could be striking, such as when a stainless steel kitchen sink is cleaned for the first time in some time, she said.

“It retains its shine for a while, but if you clean it up it’s like, ‘Oh, wow, that’s what it’s supposed to look like.'”


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