A hundred experts, laser technology and 18th-century iron to save a Madrid icon

Francisco Sabatini was not an artist or a very creative man, but he understood the desires of a king. This explains why one of his works, the Madrid Gateway – which is not the first in the city or by the architect – is a symbol of the capital and modern European history. Before it existed, medieval gates were erected in its place to receive queens traveling from the road to Catalonia and spending the night at the Retiro Palace. As long as Charles III wanted his own door, permanent, it would catch news of the Italian sovereign who had recently arrived in Madrid, proclaiming the city to be the seat of enlightenment and absolute monarchy, a model exported to America. . Sabatini also understood that.

A colossal royal shield rests on the eastern pedestal Alcalá Gate. She is in the arms of Fame, the winged maiden who lost her trumpet long ago and, in January 2021, experienced Philomena’s passage. Snow ruffled its feathers and technicians from the Madrid City Council went to check the damage. There, 23 meters above the ground, they discovered the remaining damage to the monument, 245 years of climate (snow, rain, wind, sunlight), biological (lichens, bird droppings, microbes) and environmental attacks (pollution, aerosols, organic waste from Retiro Park ). What started with a few cracks in Fam’s wing turned into the largest restoration ever undertaken at Puerta de Alcalá.

At the beginning of 2022, the Council signed an agreement with the Spanish Institute of Cultural Heritage (IPCE) for the first vision. That summer, thirty years after its last restoration in 1992, Sabatini’s work was covered in scaffolding and hyper-realistic canvas, which, barring unforeseen events, will finally be removed before this Christmas Eve. What happened under that silk screen replica in the last 16 months? This is the story of a monumental operating room involving a hundred specialists, which cost the municipal treasury 3 million euros and combines modern techniques such as photogrammetry and chemical tests with a century-old iron forge. XVIII.

During the first four months of the covert, the gate, built between 1769 and 1778, underwent in-depth analysis. “We did some basic research to know what we were facing; otherwise working would have been a leap into the void,” explains IPCE conservator-restorer, Ana Laporte, on the day at the top of the Puerta de Alcalá, where all those responsible for the project met for the final decision. The team dedicated itself to documentary research and the subject matter of the work. They combed every available archive, including designs and documents in Sabatini’s own handwriting, combing every inch of granite and limestone for any clue to his past.

There were a thousand and one tests to identify a thousand and one factors affecting the monument: scanning by drones to create a three-dimensional model, thermographic and climatic studies, reports of micro-vibrations of the metro passing underground, material tasting campaigns, the coding of each test follows scientific methods… “With serious diagnosis, We found an impressive list of pathologies,” recalls Heritage Deputy Municipal Director Maria Domingo. With the results in hand, the council summoned the press and announced that they needed to act “immediately”.

The Riddle of Stone and Iron

The east facade is crowned by Fame and four angels, through which Charles III wanted to present to visitors Madrid’s code of ethics, the four virtues listed by Plato. Strength, Temperance, Justice and Prudence. The plain west face is decorated with panoply (collections of arms) and two reclining military torsos, overlooking sunrise and sunset above the inscription “Rage Carol III”, an attempt by the king to guarantee peace to the subjects. Fixing all these groups of sculptures is a huge challenge for restorers. A panoply is made up of eight different pieces ranging from 50 to 1,800 kg. Iron bearing tons of limestone corroded and the stone was pale, black, with corroded spots, biological crusts, water pockets or lichens.

“I was amazed by the grandeur, the detail and the sculptural display, because they are superficial. It’s like a Lego, but made of stone and iron. The weights are very intricately distributed, and we had to understand how they were stitched together,” says architect and construction director Laura Lopez. . 3DTech designed special towers, a kind of holding cage, to safely examine each wound with a backometer (a device that emits sound frequencies that bounce off the stone). “Some of the fissures seemed like a small insignificant hair, but with this tool we saw that they penetrated a lot into the stone, and in others, they looked dangerous,” says Blanca Mora, head of restoration and restoration. Traditional service. History of the Town Hall.

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After removing the sculptures from the poorly preserved mortars and deciphering their skeletons, the blacksmith came into play. A forge was established at the foot of the Puerta de Alcalá, as current iron does not have the same properties as in the 18th century. Staples that now straighten angels and shields were outlined with hammer blows from another era and liquid lead was poured over them, perhaps one of the most beautiful processes of restoration. “We’ve recovered the original iron, in the old way, within the structural calculations of the 21st century,” celebrates López, standing next to one of the military ensembles, now clean and white, trimmed with metal ribbons supporting a stone puzzle.

Leading frame

Unlike other modern triumphal arches, the Puerta de Alcalá – a hollow shell covered in brick and granite – does not have a staircase. Roof maintenance is especially problematic. “Although the condition looked good, the lead had deteriorated and caused high humidity inside,” says Victoria Sanstedt, head of the council’s cultural heritage restoration department. The stone filters the water and the liquid has only one escape. “The door could not breathe, the monuments also breathe. But the water always escapes, and it did so through the chimney-like sculptures,” explains architect López.

The roof was patched on previous occasions and completely replaced in 1977 and 1992. But they were a few weeks of reconstruction; This time it took experts a year to design a different model. A metal structure flies over the air chamber and above, the lead cover, which also protects the sculptures. “We’ve solved the back with its own leading frame to prevent water from pooling in the back,” says Blanca Mora.

Documentaries, chemists, sculptors, engineers, art historians, biologists, blacksmiths, archaeologists… have participated in prescribing and using the medicine of Puerta de Alcalá. 1992 Laser technology to destroy scabs, brushes and chisels to remove mortars, chemical repellents to repel pigeons, biocides to repel fungi. Every ornament, every cornice, every bronze letter, every joint is carefully treated. “Even the scaffolding is assembled with great care so as not to touch a single stone while we reach it to restore it,” says Carmen Gutierrez, construction manager of Fernández Molina construction company. The only thing that can’t be fixed: the scars of five battles and the attack engraved on the door.

In this long project, “the most difficult thing is the planning, especially at the end; “We are many cooks in the same soup,” highlights the construction managing director Natalia González (3DTech). Being in a traffic-free roundabout is an added complication. The municipal contract considered a twelve-month implementation period, but Cibeles Madrid City Council wants its Puerta de Alcalá to be ready for Christmas.

On November 21, the southern part of the door had already been discovered and Jema Sanz, head of the capital’s antiquities intervention unit, observed it “with pity”. Because macrosurgery is facing its final stretch.

How many years will the door last until the next restoration?

“I hope I’m retired by now,” replied Sans with a smile. Anyway, we’ll do a rolling review. Not in 15 years, but now.

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