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Cal

The most basic ingredient in Mayan culture is arguably cal – a derivative of limestone.

The history of the use of cal among the Maya is vast and inscrutable. It seems fitting that the mammoth, flat platform for our land, our homes, our farms – limestone – should also find a place in our building materials, in the paints we use to color our walls, and in fact even in the very food we eat.

The Spanish word “cal” (known as ta’an in Maya and lime in English) is derived from the original Latin calx, meaning “calcium” or “limestone” (calcium carbonate). In fact, cal is a white powder that in chemistry is known as calcium oxide. It is produced by a chemical reaction that happens when common limestone is heated at very high temperatures. When hot, calcium oxide is yellow, but as it cools it slowly changes to become the characteristic pure white. When calcium oxide is mixed with water, it reacts to form calcium hydroxide, also known as “slaked lime.”

Cal and its uses were discovered independently the world over. It is found in food and building materials throughout Mesoamerica, but the Maya are credited for refining the production technique around 900 B.C. This is remarkable in the sense that to produce cal, the limestone must be heated to temperatures greater than 900° Celsius (1652° Fahrenheit).

Perhaps the most surprising use of cal among the Maya, and indeed all indigenous peoples of Mesoamerica, is in the process known as nixtamalization. In this process, dried field corn is boiled in water mixed with cal and left to sit overnight. By the next morning, the corn is rehydrated, more flavorful, and some four times more nutritious due to the absorption of calcium. This softened corn is then ground into a paste – masa – which forms the basis of the Mexican diet, from tortillas and tamales, to snacks and even beverages.

Another important use of cal among the Maya was to make concrete. Simply put, cal is mixed with water and an aggregate such as sand or gravel. When exposed to air, the slaked lime in the mixture reabsorbs carbon dioxide from the air to become hard, durable calcium carbonate again. In effect, it turns back into limestone. This is the basis for all Mayan construction, in which stone rubble work was cemented together using this material, and then coated with stucco – the same cal mixture using a much finer aggregate.

Finally, cal is also used locally to mix with natural, earthen pigments, creating a durable and tactile paint.

The benefits of cal as a building material in the tropics are many. It is extremely long lasting (think of the pyramids!), and it has the ability to breathe. Homes built with lime mortars and stucco create a comfortable interior atmosphere; these “hygroscopic” materials stabilize the relative humidity by absorbing and releasing moisture. Further, cal materials have self-healing capabilities: fine cracks often develop in plaster surfaces, but with cal stucco and paint, normal water absorption can dissolve the lime; as the water evaporates, this “reconstituted” lime is deposited in the cracks and begins to seal them. And unlike harder cements or vinyl paints, cal materials do not result in trapped moisture, which is known as one of the major causes of building decay in the humid tropics.


Estuco

The finishing touch on mampostería, estuco or "stucco" has been used by the Maya for centuries to seal crude stone structures and provide a smooth surface for painting.

The dramatic stone ruins we see today at the various archaeological sites were once covered in stucco and colorfully painted. Made primarily from cal and very fine sand, stucco is applied while soft to cover both exterior and interior walls.


 Mampostería 

Visit any Mayan ruin – from the massive pyramids of Chichén Itzá to the tranquil courtyards of Uxmal – and you will see the Mayan building technique the Spanish called mampostería.

Simply described, it is rubble stone held together with cal cement, then covered with cal stucco and painted. When the Spanish brought their version of Roman building styles to the new world, they relied on local masons to execute the designs. The result: the many colonial homes and public buildings throughout Yucatán and Mérida’s Colonia Centro that feature the cooling effects of 60cm (2 feet) thick mampostería stone walls. Nowadays, new construction might be completed with concrete blocks and the cal cement and stucco, but the basic building methods have not changed for centuries. 


Marseille tile

Not so much a tile as it is roofing material, this French import known as the “Marseille tile” was based on a design created by the Gilardoni Brothers in 1850.

The Société des Tuileries et Céramiques – a group of manufacturers in Marseille (or Marseilles), France – refined the original design and commercialized large numbers of the new interlocking tile. The tiles were enormously popular outside their country of origin, and were exported to such far-flung places as Yucatán and New Zealand. Gray clay was used in Europe and red terracotta was shipped to tropical climates. The tiles were ingeniously designed to link together and rest on wood or iron support beams.

Throughout Latin America, the roofs built using such tiles (or tejas) are known as tejado. In Yucatán, the tiles were often placed in the grooves of iron railroad ties used as roof trusses, then covered with stucco.

 

 

 

 

 

 

  

Both newly produced tiles and antique ones can be found in Mérida, identified by the distinctive imprint that reads MARSEILLE. These tiles are still available, but are much less widely used, having been replaced by cement blocks designed especially for roofing.

 

 


Vigas

Another distinctive feature of Yucatecan architecture is the pronounced ceiling beams that are visible in most buildings dating from the Colonial period through the early years of the Porfiriato.

Originally the beams were made of tropical hardwoods; interstices were filled with bricks, then stuccoed. Later, during the great era of railroads, the iron I-beams were recycled and used as roof supports. It was at this time that the Marseilles tile was also popularized, the interlocking pieces resting in the channels of the beams. When vigas are found intact in a restoration project, structural weaknesses must be investigated, but when possible they should be saved. Restoration may include additional trusses or other support, stripping off old paint finishes and sealing with new water-resistant paints. 

 
 
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