The Angel of Independence (El Angel de la Independencia) – an iconic and endearing symbol of Mexican freedom – has stood watch over Mexico City since 1910 when it was erected to commemorate the country’s liberation from imperial Spain. From its inception, the monument has been one of Mexico City’s most important attractions and its placement in the heart of the capital on the Paseo de la Reforma underscores its importance to the county’s proud national identity.
But as the environmental impact of Mexico’s economic growth throughout the 20th century took its toll on the monument, corroding its stone base and tarnishing the gold-leaved statue that sits atop the structure, officials recognized the need to take action. In 2006, a team of coatings and restoration experts was brought in to help the famous monument regain its regal luster.
Headed by Marina Estevez, a coatings specialist for Eastman, the team worked with Pinturas El Nervion, S.A. de C.V., a well-known manufacturer of specialty paints and coatings in Mexico, to develop a special clear-coat varnish using Eastman Cellulose Acetate Butyrate (CAB), an additive widely used in architectural paints and varnishes and coatings for cars, laptops and cell phones. Not only will the Eastman CABs penetrate and strengthen the numerous surfaces of the monument, it will also prevent water damage and environmental degradation while allowing for natural surface breathability.
“After nearly 100 years of wear, the Angel of Independence was in need of a major facelift,” explains Estevez, who both developed the formulation and played a key role in its application.
While the monument has undergone two restorations in the past – following a 1957 earthquake in which the monument collapsed and after World Cup victory celebrations in 1986 caused extensive damage – the most recent project paid special heed to the architect’s original intent, from materials and designs down to textures, to restore the monument in all of its glory.
The team took a top-to-bottom approach to the cleaning and restoration of El Angel – as the monument is affectionately known in Mexico – refurbishing every inch of the 36-meter structure from the nearly seven-meter gold-leafed statue adorning the top of the monument to its stone column and four granite obelisks and four bronze sculptures that guards its base.
The first step in the restoration and preservation effort of the statue itself involved an application of anti-corrosion primer followed by a fine layer of clay. On the top layer of the statue sits a fine layer of gold leaf.
“The gold-leaved statue is the most stunning feature of El Angel and one of our biggest challenges was to make it shine,” says Juan Jose, chief architect in the restoration project. “When we started, the gold leaf was non-uniform and of low quality. Water and smoke has seeped into cracks, causing it to corrode.”
The challenge was to restore the brilliance and clarity of the gold without compromising its integrity. To solve this problem, the team used 23.75 carats of gold sheeting and Eastman CABs were meticulously applied to the statue’s body, feet and wings. Surface leveling and texture were monitored scrupulously to ensure a smooth continuous surface. In some cases, old paint was even removed before being covered with two coats of varnish and a thicker layer of CABs were applied to reduce sagging and prevent dust from adhering to the gold leafing.
Restoration on the column, base, obelisks and statues consisted of a thorough cleaning and crack-sealing process followed by a coating of CABs. Eastman CAB accounted for five percent of the clear-coat varnish formulation and, according to Estevez, was crucial for its flow control, surface leveling, flexibility and UV resistance.
“Eastman CABs are extremely well suited to architectural coating restoration projects for a number of reasons, including their durability and ease of use, but given Mexico City’s elevation, UV resistance proved to be a particularly relevant advantage,” she says.
The slow dry time of the formulation was also crucial to the project’s overall success, explains Jose. “Gold leaf is extremely sensitive to the touch, making it crucial to have a fast dry time when using any surface coatings. The CAB formulation dry time of 25-30 minutes – compared to a 40-minute dry time for other coatings options – gave our workers a significant advantage.
Estevez and the team had confidence in the process because Eastman CAB is most commonly used in industrial maintenance applications that test performance additives in the most extreme conditions.
The CABs had also been used for architectural coatings in Mexico before. In fact, they were first used to great success only miles away from El Angel in XX to restore the dome of the Mexico City opera house, El Palacio de Bellas Artes. Also of note, Eastman CABs were used to clear coat and protect large copper pots at a large Mexican brewery for over a decade.
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