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Notre Dame Officials Look to Lasers for Cleaning

Friday, January 8, 2021

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Progress is continuing at the Notre Dame Cathedral, where a fire ravaged the 850-year-old structure in April 2019.

The cathedral’s massive organ has been disassembled ahead of schedule, according to officials, and workers have completed the meticulous task of removing all of the construction scaffolding that had melted during the fire.

New scaffolding is now being erected inside the building as decontamination and cleaning continues ahead of restoration and rebuilding work.

The cleaning is especially important as the lead roof was a casualty of the fire, billowing yellow smoke into the air and coating the entire area with lead dust, causing the surrounding neighborhood to be decontaminated afterward and an immense amount of precaution chained to the work that takes place inside now.

One technology that workers are considering implementing is lasers. Chicago-based GC Laser Systems, led by art restoration expert Bartosz Dajnowski, was texted inside the structure in the fall.

The technique is used with the goal of weeding out contamination without using chemical or mechanical abrasion.

GodefroyParis, CC-SA 4.0, via Wikimedia Commons

Progress is continuing at the Notre Dame Cathedral, where a fire ravaged the 850-year-old structure in April 2019.

“What we do is we calibrate our laser technology to excite the layer of contamination with laser pulses,” he said. “And when that contamination gets hit by a laser pulse, the molecules get so excited by the energy that they absorb, they literally shake themselves apart and just vaporize off the surface.”

A fume capture system catches everything that comes off, but more importantly, the tools can be carefully calibrated to pinpoint what exactly is removed.

"Every material absorbs light differently based on its color and based on its composition. And what we do is we calibrate the parameters of a laser light to excite one material but not another based on how it absorbs infrared," said Dajnowski.

This means that soot left over from candles, for example, could be left behind so that the cathedral isn’t left looking brand new, an attempt to preserve the structure’s aesthetic as well as materials.

Meanwhile, the debate on aesthetic was reignited last month, when a draft of plans was published in the French media, according to the National Catholic Register. Reportedly, a committee appointed by Archbishop Michel Aupetit comprised of different experts and clergymen had come up with some proposals for the interior restoration, some of which included replacing the historic glass-stained windows in the chapel’s nave with more contemporary ones.

Other significant changes include furniture and different lighting, which prompted immediate dissent from members of the French public. So much so that the Archdiocese of Paris published a press release, restating that the ideas were only a draft with the intention on allowing visitors to better experience the cathedral.

The diocese also noted that details were yet to be discussed with the national authorities that ultimately make the decisions. In addition, the law passed in July 2019 mandates that any funds that were raised immediately following the blaze are to go only to restoration and conservation work, meaning if any other plans are made, other funding must be acquired as well.

The project draft is slated to be presented to officials in the first half of this year. The restoration team is shooting for the first Mass to be held on April 15, 2024, the five-year anniversary of the fire.

Fire Background

On the evening of April 15, 2019, flames engulfed the more than 850-year-old Notre Dame Cathedral, destroying the spire and nearly two-thirds of the roof.

With the help of about 500 firefighters battling the blaze, the fire was brought under control by the early hours of the following morning, five hours after the outbreak. Officials stated that no fatalities took place during the incident, and only one firefighter was reported to have experienced serious injuries.

There were no initial reports about what had caused the blaze, though police said at the time that it appeared to be accidental and that the cause could be linked to the ongoing 6-million-euro ($6.8 million) renovations. Since then, though, investigators have said they believe an electrical short-circuit is the culprit.

City and national officials have since been criticized for failing to fully disclose the risk of contamination as a result of 440 tons of lead roofing that had burned in the fire, which consequently sent clouds of lead particles into the air. Work was suspended for weeks over the summer, while the surrounding area underwent lead testing.

On Aug. 13, maintenance and cleanup practices commenced in Notre Dame’s 100,000-square-foot enclosed plaza and on surrounding streets.

The process involved vacuuming, scrubbing and rinsing the pavement and various surfaces using a highly pressurized water mixer combined with a special particle compound used to remove lead. The wastewater was then recovered.

On more dense surfaces like granite, workers use a special gel to coat the contaminated surface, which is left to dry for several days and is then removed, pulling out any lead particles that have become embedded in the stone.

Although environmental associations, labor unions and other groups agree that cleanup procedures should have begun months ago, new decontamination measures have been established for workers at the cathedral. Through the use of foot baths, showers and wearing of disposable uniforms, workers are both more protected and less likely to spread toxic particles outside of the plaza. Strict check-ins and check-outs were also employed.

Restoration

President Emmanuel Macron has specified that he wants the monument to be rebuilt in time for the 2024 Summer Olympics, slated to be held in Paris. To aid this goal, digital 3D scans taken by the late Andrew Tallon of New York’s Vassar College in 2015 are believed to provide the necessary information for fast-track construction.

However, before restoration efforts can begin, the melted scaffolding needs to be taken down—piece by piece (which is what’s happening now).

If the scaffolding were to fall or collapse, it could reportedly put other parts of the building in jeopardy, so workers will have to first build a structure above the scaffolding that will allow them to rappel down.

Officials began taking down the 50,000 metal tubes that make up the lattice in October. While they’re dismantling the lattice, they are also installing planks above and below the cathedral’s ceiling for closer examination.

At the beginning of the year, the ultimate fate of the structure was still unknown.

In mid-March, the process was delayed because of the COVID-19 pandemic; however, French general Jean-Louis Georgelin, who is heading up the 40-person committee that is overseeing the restoration, told The Guardian at the time that the unexpected pauses in work should not impact the deadline.

Delays included specialist artisan builders being sent home as France went on lockdown, as well work being stopped before it began on the removal of the damaged scaffolding.

Georgelin had also noted that monitoring equipment attached to different parts of the structure indicated that there has been no movement in the last year.

At the end of April, the site was retrofitted for the virus, which included rearranging showers and cloakrooms as well as installing a place to eat. In addition, most workers are now staying at vacant hotels in order to not use public transportation.

Work officially resumed at the site in May.

In June, the dismantling process restarted. Two teams of five workers each took  turns descending on ropes into the scaffolding, which was made up of 40,000 pieces, and cut with saws through the metal tubes that fused together. The pieces were then lifted out via crane.

Design

Possible design changes for the cathedral’s spire erupted just days after the fire, and French Prime Minister Edouard Philippe even launched a spire design competition, saying that instead of recreating the original spire, the city hoped to create a new design that is “adapted to the techniques and the challenges of our era.”

Since the spire was not a part of the original structure, or even the first spire built for the cathedral—the first spire was believed to be built between 13th and 18th centuries, and was removed due to wind damage; the second spire was added during the 19th century restoration by French architect Eugène Viollet-le-Duc—questions about replicating the tower arose.

The founder of Farshid Moussavi Architecture (London), Farshid Moussavi said that a new opportunity has been presented in bringing together talent and donations to rebuild Notre Dame, much like when the structure was originally built.

“The rebuilding of Notre-Dame is an opportunity to expand that history,” Moussavi said at the time.

“Whereas the political landscape in the Gothic era was based on each country competing with each other to show their piety, today, we can come together as an international community to rebuild Notre-Dame because it is a world heritage landmark.”

Since then, several ideas have been revealed, including: Italian architects Massimiliano and Doriana Fuksas proposed a contemporary roof and spire made from Baccarat crystals that would be lit up every evening; French designer Mathieu Lehanneur proposed a golden, fire-like structure; Bratislava-based Vizumatelier proposed a lightweight tower that would shine a beam of light directly upward; Cyprus collaborative architectural studio Kiss The Architect suggested various arches and balls wrapped around a central staircase-type spire; and Paris-based architects Studio NAB have submitted a design proposing a greenhouse and educational apiary to sit upon the damaged landmark.

However, about a month after the fire, the French Senate passed a bill that would require the cathedral to be rebuilt to its “last known visual state,” a move that pushed back against the proposed innovation for the structure.

The legislation was introduced in order to allow for the fast-tracking of reconstruction that Macron proposed. However, some other facets were changed as well, including a clause that would give the government the power to override regulations on planning, environmental and heritage protection and public tenders, according to The Local.

The law also dictates that the government create a “public project” to oversee the construction project, overseen by the Ministry of Culture.

In July of last year, Macron dropped the idea of a modernized spire.

   

Tagged categories: Churches; EMEA (Europe, Middle East and Africa); EU; Fire; Health and safety; Historic Preservation; Historic Structures; Lead; Maintenance + Renovation; Restoration; Safety

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