The Gaudí method: geometry and nature

Almost everything that is said about how Gaudí worked is actually the opposite of the truth. It's said that he didn't create blueprints, but he did. It's said that he copied nature, but he didn't. It's said that he invented the "trencadís" technique to use broken ceramics, but he didn't invent it, and it wasn't even about saving money.

Here's the method, with the geometry explained without formulas, and with the exact location of each building where you can observe it in operation. It's best read while standing in front of the building, rather than reading it on the couch.

His central tool was a polyfunctional model, assembled in a shed built next to the construction site of the crypt of the Colònia Güell. On the ceiling, there was a board with the building's plan. From the board hung cords, and from the cords hung small cloth bags filled with lead shot, proportional to the loads that each point would actually have to bear.

When hung, a rope naturally adopts the only form that works under pure tension, without bending. Gaudí would photograph the entire structure and then invert the photograph. What hangs downwards, inverted, is exactly what supports it upwards, and only under compression, which is what stone and brick are capable of. He would then paint the final outline in gouache or pastel over these inverted photographs. The structure was not calculated after the drawing; the structure was the drawing.

The model was built to a scale of 1:10 and measured four meters in height. It was not created by a single person. Those who worked on it included Francesc Berenguer, the model maker Joan Bertran, the bricklayer Agustí Massip, the carpenter Joan Munné, and the Alsatian engineer Eduard Goetz. It is repeatedly stated that it took ten years, a figure derived from subtracting 1898 from 1908, and which no source confirms. The original was destroyed in July 1936; what exists today is a reconstruction made in Stuttgart in 1982 under the direction of Frei Otto.

A catenary is the shape that a chain takes when suspended from its two ends, with the weight distributed along the chain itself. A parabola is the shape that a cable takes when the weight is distributed along the horizontal, as in a suspension bridge. They are distinct curves, and in short spans, they look so similar that sources contradict each other regarding the same building: the Casa Milà is a prime example, and it is shown below.

The official definition of the basilica is shorter than any explanation: the catenary arch is "the shape that a rope or chain suspended from both ends takes," and "it is stable on its own; it does not need other supporting elements." That's it. A semicircular arch pushes outwards, and it needs to be supported from the outside; an inverted catenary arch does not push, it supports itself. That's why Gaudí used the word "crutches" for the flying buttresses of Gothic architecture.

A ruled surface, according to the official definition, is "the surface generated by a straight line that moves." It sounds abstract, but it actually means the opposite: that a curved surface can be recreated, framed, and shaped using straight edges, taut strings, and straight tools. This is the practical reason why a building like this can be constructed, and not simply a matter of aesthetic preference.

The Schools of the Sagrada Família deserve a separate paragraph. They are a building measuring 10 by 20 meters and 5 meters high, with three classrooms for the children of the workers, featuring conical partition walls and a roof that are supported without an interior structure. They cost 9,000 pesetas, which Gaudí paid from his own pocket. They were damaged during the attack on July 20, 1936, and were rebuilt in 1937. And in 1928, two years after his death, Le Corbusier drew them when he visited them: the most humble work in the complex is the one that ended up in the notebook of the most influential architect of the century.

The catenary arch appears in Gaudí's work earlier than almost anything else, and he never abandons it. These are the places where you can see it, along with the number published by each developer, and the declared space where no number is published.

"Gaudí argued that a column that is well inclined is more stable than a vertical one," writes the Informative Notebook 4. It sounds like a paradox until you look at an arch: the weight doesn't go straight down, it goes diagonally. A vertical column receives this diagonal and converts it into a lateral thrust that must be counteracted from the outside. A column oriented in the direction in which the load wants to go works only in compression and doesn't push anything. The portico of the Passion facade uses this principle with six and eighteen columns inclined in two levels. In the Park Güell, the three viaducts, five meters wide, do the same with unworked stone taken directly from the site.

First. It is not documented that it was first used at the Güell Estate. The stable at the estate is often cited as the first application, but those who repeat this information do not provide a source. The first documented application with solid evidence are the chimneys of the Palau Güell (1886-1890), using ceramics from the Pujol i Bausis factory in Esplugues.

Second. La Casa Vicens and El Capricho do not have "trencadís". What they do have is ceramic in whole and modular pieces, which is a different technique and creates a different effect. The "trencadís" technique, as a system, is from Park Güell.

Thirdly, and this is the one that is most repeated: it is not recycling. The glazed ceramic was chosen for optical reasons, because it reflects and changes with the light and the angle from which it is viewed. Presenting it as environmentalism prematurely is projecting backwards a concern that was not theirs. It is true that the Tallers Pelegrí gave away the broken glass from the facade of the Casa Batlló, and this is a specific incident, not a method.

Who executed it also matters. The Pujol i Bausis factory, now the Museu de Ceràmica La Rajoleta. The ceramicist Sebastià Ribó, author of the blue, scale-like pieces in Casa Batlló, using the engalbar technique. And the builder Josep Bayó i Font (1878-1970), who oversaw the construction of Casa Batlló and Casa Milà, and who, incidentally, is the source of many of the anecdotes that are told today without mentioning him.

Josep Maria Jujol (Tarragona, September 16, 1879 - May 1, 1949) graduated on May 18, 1906, so he began working with Gaudí before becoming an architect. He was presented by Dr. Pere Santaló, a doctor and friend of Gaudí. When he exactly joined is disputed: Flores, Ràfols, and Duran place him in 1904-05; Bassegoda, after 1906, which would exclude Jujol from the initial phases of the Casa Batlló. He left the studio in 1915.

Not all responsibilities carry the same weight, and acknowledging this is more helpful than simply distributing praise indiscriminately.

• High security: The panels from the hypostyle hall and the bench at Park Güell, which the park itself describes as "designed by Josep M. Jujol."
• High security: the color of the facade of Casa Batlló. Solà-Morales describes it this way: "The design of the facade is by Gaudí, but the color scheme was by Jujol, with great autonomy."
• High security: the plasters and paints of Casa Milà.
• Controversial: the railings of Casa Milà. There are three fountains and three different authors: Jujol, the Badia brothers, or Gaudí himself, according to the official website, which does not mention Jujol.

The procedure was a process of trial and error, with a workshop installed next to the building and few detailed drawings. Plaster models were made at scales of 1:10 and 1:25. The model of the main building was intended to be used for all the buildings; the model of the sacristy, for the central towers. In Casa Milà, the plasterer Joan Bertran created a model that was later deliberately broken and taken to the construction site in pieces, so that each stonemason would have the exact piece they were carving in front of them. This is attested by Josep Bayó, and it is Bassegoda, not Martinell, who records it.

There's another layer to the method that needs to be addressed with the caveat in mind. He studied gestures and skeletons, used wire mannequins, photographed using a system of mirrors to obtain multiple perspectives at once, made plaster casts of people and animals (once, he hoisted a donkey with pulleys so it would stay still), and adjusted the proportions according to the final height of the figure: the higher it was to be, the larger he made it. All of this comes from a single source, and it is informative: Gómez Gimeno (2006, pp. 76-77). The most gruesome versions circulating on the internet, with skeletons and newborns brought from the hospital, have no basis in reality, and the proper name often attributed to the donkey does not appear in any source.

From this, a consequence arises that almost no one points out: that method produced photographs. When, on July 20, 1936, the blueprints were burned and the plaster models were destroyed, the reconstruction was partly possible thanks to the photos and the albums of the temple from 1915 to 1929. A few days after the attack, Lluís Bonet i Garí requested that the fragments be collected; since 1940, he, Puig i Boada, and Quintana recreated the models using those pieces and those images.

The phrase that best summarizes this is from the Informative Notebook 3: "Gaudí didn't copy nature, but rather analyzed the functioning of its elements." The ruled surfaces didn't occur to him; he found them, and he said where: in reeds, canes, or bones, which are hollow structures capable of withstanding a lot with very little material. He studied in Montserrat, in the caves of Mallorca, in the Cova del Salnitre in Collbató, in the gola de Fraguerau in the Muntanyes de Prades mountains, behind Reus, and in Sant Miquel del Fai.

And a clarification about the most famous quote of all. "The straight line is of man, the curve is of God" circulates in Spanish everywhere without a primary source. The documented version is in Catalan, recorded by Joan Bergós in 1954 (p. 91), with context and an approximate date, around 1920-1926: "The straight line is of men; the curve is of God." However, the conclusion usually drawn from it is false: there are his buildings with straight walls and prismatic volumes, such as the Casa Botines in Astorga, the Teresianas, or Bellesguard. And ruled surfaces are, by definition, generated by moving straight lines.