La Historia de los Revestimientos: La Civilización Antigua y los Períodos Clásicos

Çatalhöyük fresco,  (ca. 7500 AC)

El arte de hacer revestimientos continuos es tan antiguo como la civilización, de hecho, dicho de un modo más enfático, sin  revestimiento no hay civilización. La habilidad humana de abandonar la cueva, construir su hábitat a base de piedras o cañas y cubrirlo con morteros de tierra, permitió al hombre crear la “cueva” deseada. La construcción de viviendas permanentes cerca del agua dulce y en una posición defendible o contigua a tierras cultivables, significó para la humanidad el inicio de la vida en comunidad y se empezaron a formar las primeras ciudades.

Los primeros revestimientos fueron hechos con tierra. Estos consistían en una sencilla mezcla de arcilla, arena y paja que no necesita fraguar y simplemente se seca con el sol. La misma mezcla se empleaba para hacer ladrillos en moldes. Estas técnicas de construcción con tierra son aún a día de hoy de las más usadas a nivel mundial.

Los revestimientos de calcio, ya sea a base de cal o yeso fueron descubiertos durante la producción de alfarería. Por casualidad, se seleccionaron piedras de yeso y cal para construir el horno donde se cocía la cerámica. El calor del fuego hizo desaparecer el contenido de agua de las piedras de cal y de yeso haciéndolas friables y convirtiéndolas en polvo, cuando el agua se añadía a las brasas para apagar el fuego, se descubrió que el polvo había creado una pasta que endurecía rápidamente.

La Civilización Antigua

Uno de los primeros ejemplos arqueológicos de ambos; de la civilización y de los revestimientos, se encuentra en Çatalhöyük (ca. 7500 AC) todavía presente a dia de hoy en Turquía. Se trata de un denso conjunto urbano hecho con ladrillos de barro, los suelos y las paredes están revestidas con el material del suelo local; una marga arcillosa que sirvió para hacer un revestimiento adecuado. Lo poco que sabemos de esta civilización antigua sobrevive en los frescos pintados representando numerosas escenas de caza, volcanes y patrones geométricos a modo de pura expresión decorativa.

Nefertiti

Los mejores ejemplos de revestimientos del Periodo  Preclásico se encuentran en la monumental arquitectura del antiguo Egipto con fecha del 3er milenio AC. Estas construcciones incluyen las pirámides de Giza hechas con  morteros de yeso y cal, y con revestimientos exteriores acabados con uno fino estuco de cal. Innumerables trabajos de frescos y ornamentos permanecen, así como el renombrado  busto de Nefertiti hecho con yeso que demuestra el paralelo desarrollo artístico de revestimientos decorativos. De hecho, la cal y el yeso producidos en Egipto fueron en muchos casos de calidad superior a la que se encuentra comercialmente hoy en día. Esto nos da el testimonio del hecho empírico de que la producción material de revestimiento refinados empezó muchas generaciones atrás.

La civilización Minoica emergió en el 2º milenio AC en la isla del Mediterráneo de Creta. Los minoicos fueron enormemente influenciados por los todavía exitosos Egipcios, como evidencia  arquitectónica está el Palacio de Cnosos y El palacio Festos.

Aun así, los minoicos fueron distinguidos por su extensivo uso de revestimientos en los espacios interiores. A comparación de los motivos egipcios elaborados en seco, los minoicos hicieron exuberantes y coloridas decoraciones al fresco. Aun manteniendo la vista de perfil y el contorno típico del arte egipcio, las técnicas del buon fresco empleadas por los artesanos minoicos obligó a una manera más rápida e improvisada de trabajar, resultando así una estética más fluida y vibrante.

El Período Clásico

Los micénicos reemplazaron a los minoicos y se convirtieron en la cultura dominante de Creta y del archipiélago griego manteniendo y refinando el estilo arquitectónico Minoico.

Aun así, Roma, caería por siglos a manos de los bárbaros sumergiendo a Europa en los años oscuros. Micenas, tuvo un destino similar a manos de las tribus conquistadoras Dóricas y Jónicas. Durante los años oscuros griegos se perdieron muchos conocimientos de la construcción y de la arquitectura  adquiridos durante siglos.

Finalmente, en siglo 8 AC, los dos grupos rivales se unieron para formar el pueblo Heleno y establecieron su cultura, la cual ha dejado un imborrable rastro en nuestra civilización humana.

Aunque el uso del revestimiento nunca cesó por completo, estos también tuvieron un renacimiento durante la Grecia Helénica. Gracias a los griegos tenemos la palabra Española “yeso”, derivada directamente de "gypsos" (γύψος) en griego. Del mismo modo, es fácil ver la correlación entre nuestra palabra "emplastar" con "emplastron" (εμπλαστρον) en griego, que significa "embadurnar con masa”.

Más allá del legado de la deuda de vocabulario griego, debemos también el mismo fundamento para nuestro patrimonio arquitectónico occidental. La máxima expresión de ornamentación y la representación de los órdenes arquitectónicos griegas: los dórico, jónico y corintio, continúa siendo hoy en día realizada en yeso.

Los griegos fueron invadidos militarmente por los romanos en el s.146 AC. Rápidamente, los romanos fueron simultáneamente cautivados por la cultura griega y adaptándola e incorporando a su filosofía, arte y arquitectura. Los romanos continuaron con su tradición de arquitectura templo; aun así, extendieron su arquitectura monumental para incluir basílicas seculares, monumentos imperiales y villas de palacio. La Domus Aurea “Casa de Oro” del Emperador Nerón y descubrimientos similares en Pompeya y Herculaneum son buenos ejemplos de cómo los revestimientos con cal trajeron el artístico cenit para la élite romana. Estos lugares ofrecen entrever el pasado, una era de opulencia, de lujosos interiores realizados con revestimientos finos muy decorativos, habitaciones enteras pintadas al fresco y bóvedas de cañón conferidas con suntuosas ornamentaciones en bajo
relieve.

Pompeiian Thermae

Los Romanos trajeron no solo grandes artistas y arquitectos, sino que también formidables ingenieros. Un tesoro permanece para nosotros; el exhaustivo tratado arquitectónico, Architectura, datado del siglo 1.AC escrito por el militar Marcus Polio Vitruvius. En su trabajo, conocido comúnmente como Los de libros de Arquitectura, Vitruvio dedica tres capítulos del libro II , para la selección de arena, cal y puzolanas para trabajos de estucos y hormigón. Además, dedicó la mayoría del libro VII a la específica preparación y aplicación de estucos de cal y pinturas al fresco.

La mayor de las civilizaciones antiguas, coincidió con el mejor desarrollo y entendimiento a la hora de hacer revestimientos. Los romanos expandieron el conocimiento más allá de los descubrimientos de los griegos: La adición de puzolanas a la cal, crearía una mezcla que fraguaba en el agua. El cemento nació a la vez que la ingeniería de la construcción estaba en crecimiento y los romanos
empezaron a construir carreteras, acueductos y puertos que todavía perduran a día de hoy. La destreza de la ingeniería romana y el descubrimiento del hormigón, culminó con su incomparable éxito arquitectónico; el Panteón. El cual permanece, siendo el domo más grande de hormigón sin reforzar que jamás se haya construido, con un diámetro interior de 142 metros a su base.

El Panteón, Roma

El tratado de Vitruvio, empezó a alcanzar su amplia publicación a principios del s.15. A finales del s.15 hay evidencia arquitectónica y escrita de las recetas de Vitruvio aplicadas en estuco hidráulico en Venecia y murano, 300 años antes de la llegada del cemento moderno. Más tarde vamos a explorar cómo sus escritos, así como los descubrimientos arqueológicos del Domus Aurea, inspiró a genios creativos como Da Vinci, Michelangelo y Raffaello al alcanzar alturas vertiginosas de la expresión
artística en fresco y estuco labrado durante el Renacimiento italiano.



Escrito por Patrick Webb

Traducido por Anna Castilla Vila

An Architectural Utopia

2001: A Space Odyssey

Utopia is a 16th century literary invention derived from the Greek οὐ, "not" and τόπος, "place". Owing to an homophonic anomaly most folks think 'Utopia' refers to a 'good place'. Sorry to be the bearer of bad news, that would be an 'Eutopia'. An Utopia in point of fact is "no place" at all. I contend that we are fast approaching a global architectural Utopia, a built environment of "no place" and "no one".

An Aesthetic Cleansing

I just cringe when I hear a designer or architect say they are after a 'clean' look. What does a 'clean' look mean anyway? After all I think very few of us would prefer a 'dirty, unclean' look! 'Clean' is code for a sparse, minimalist design bereft of craft, cleansed of ornament, devoid of the polluting evidence of the human touch. A product of industry, possible only with the precision of the machine. We can practically place a date for when this pogrom against craftmanship began in earnest, January 21st 1910, with Adolph Loos' infamous lecture "Ornament and Crime". Ornament and craft were condemned as unevolved and degenerate relics of a primitive past. A self-proclaimed liberator of the craftsman, Adolf claimed their employ by the privileged was abusive and immoral. A progressive society would free them of their toil:

"We have out-grown ornament, we have struggled through to a state without ornament. Behold, the time is at hand, fulfilment awaits us. Soon the streets of the cities will glow like white walls! Like Zion, the Holy City, the capital of heaven. It is then that fulfilment will have come.”  - Adolf Loos

The foretold aesthetic cleansing arrived, carried to its logical fulfillment. The former craftsman freed from his toil, liberated from his art could now slave as a laborer in the factories supplying the materials of industry or assembling them as a "mechanic" in the field.

A School, a Style, and the Rise of the Machine for Living

Bauhaus Dormitory

In 1919 a "House of Building" or Bauhaus was established in Germany putting Adolph Loos' ideas into practical application. Surprisingly, coursework included fine arts and several years of workshop training under the direction of craftsmen and artists. However, the emphasis was technological, the preparation of designs for mass production by industry, canonized by the adopted slogan of the Bauhaus, "Art into Industry". Industrial efficiency demanded a reductive approach, an extreme simplification and unification of design that realized the elimination of moulding and ornament.

The early efforts of the Bauhaus laid the grounds for an "International Style" unveiled in 1932 at the Museum for Modern Art in Manhattan, NY. What made the this style "international"? It certainly did not embrace the millennia of accumulated cultural traditions of many nations and peoples from across the globe. Commonly held among those various humanistic traditions, man had always been held as the subject of architectural design, the building was to be the objective reality, an outward expression reflecting his inner, spiritual nature. In stark contrast, the International Style enforced the complete extinguishment of any lingering artifacts of  human culture, employing a complete reversal of the traditional thought process of design. The new doctrine dictated that "Form" was to follow only practical "Functions". The building and the attendant practical efficiencies of construction usurped the position of subject, placing people as just one amongst many objects such as chairs, toilets, stairs etc. populating the structure. The International Style might have been more appropriately called the Extranational Style, it reflected an aesthetic beyond the cultural influence of any nation or culture. It was the first step towards a new architecture, a Utopian architecture of "no place" in particular.

Drywall Factory

If the International Style achieved an architecture of "no place", several of its visionaries would envision that the built environment of the future would likewise be an architecture of "no one". Prominent leader of the movement, Le Corbusier, declared the house the "Machine for Living". The military industrial complex in place after World War II quickly adapted itself to the mass production of industrialized construction components. Traditional, simple building assemblies, adapted to local environmental conditions, often furnished and always constructed by local craftsmen were rapidly supplanted by complex, standardized cavity wall building assemblies wholly dependent on mechanical systems designed by engineers. The establishment of international building codes would ensure that those engineered building systems were everywhere to stay.

Progress and Propaganda, The Freedom of Limited Choice

Proposed Clemson Architectural Center
Charleston, SC

There is the prevailing opinion that contemporary architecture is progressive, at least among architects who have been indoctrinated in this philosophy. Examples of progress take many forms: embracing new materials, "green, sustainable" technologies and pursuing bold, unprecedented designs. This is epitomized by the American Institute of Architects annual Progressive Architecture Award. The architectural community pats itself on the back for specifying multimillion dollar complexes utilizing high-embodied energy materials of glass, concrete and metal alloys wholly dependent on mechanical systems burning fossil fuels to function, life expectancy unknown. The architects designing these projects are "International", neither educating themselves locally nor maintaining a practice locally, nor are the highly engineered proprietary building systems they specify locally furnished. Instead, they impose a signature style, free of cultural influence, independent of craft that can be plugged into any major city: New York, London, Beijing, Dubai or ceremoniously dumped in the historic districts of traditional cities such as Rome, Kyoto or Charleston. The envisioned "Utopia" has quickly morphed into a "Dystopic" reality, an alien, uncultured, craftless built environment of "no place" in particular.

Tianjin EcoCity Ecology Museum. Courtesy Steven Holl Architects

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Contributed by Patrick Webb 

Roman Architecture: Weeks 7 & 8

Trajan's Column

I signed up last autumn for an online course from Yale University Department of Classics on Roman Architecture. The last couple of weeks we have been focusing on the emperors Trajan and Hadrian, great patrons of architecture at a time when Rome was at the peak of its power. We also received our most challenging assignment yet: To put ourselves in the place of an architect of ancient Rome competing for the major commission of a lifetime, to design and build a newly founded Roman city. To obtain the commission we must submit a proposal to the patron describing our city including drawings and a letter to the patron. I'll share what I submitted in conclusion.

Trajan 98 - 117 C.E.

Grandiosity. The most fitting word I can think to describe the architecture that Trajan would commission for Rome. The world had not seen anything like it. His first order of business was to have a forum built as large as all of the existing imperial fora combined. Though much of it was later destroyed and pillaged for marble, remarkably the famous Column of Trajan stands virtually intact. What a masterpiece! A visual "scroll" unfurls as a spiraling frieze recounting in relief the conquest of the Dacians, a people from modern day Romania who fiercely and nobly opposed the Roman conquest. There is a stairway inside that can still be climbed to the very top, a height of 125 feet, marking the amount of soil removed from the Quirinal Hill for Trajan to build his forum!

An extension of the forum and a remarkable project in its own right were the Markets of Trajan. The shear size and complexity of them makes it hard to believe it approaches 2,000 years. Serving as an ancient shopping mall it would have accommodated hundreds of vendors, the Via Condotti or 5th Avenue of its day.

Markets of Trajan

Hadrian 117 - 138 C.E.

Canopus, Hadrian's Villa

Rome could not have asked for a better architectural patron than Hadrian. He was an architect himself! Both contemporary critics and those of his day try to diminish him as an amateur; however, the attributed Temple of Venus and Roma as well as several of the projects at his sprawling villa give testimony of a gifted sense of design, combined with formal studies. Notice the use of the "Serliana" or "Palladian" opening, the original design informing these Renaissance architects who rediscovered this form some 1,400 years later.

However, the undisputed champion of Roman architecture, representing the triumph of Roman concrete and engineering skill is the Pantheon. What a remarkable accomplishment. Aside from a myriad of remarkable features there is the signature unreinforced concrete dome 142 feet across, the oculus 27 feet across and 7 1/2 feet thick at the opening. I can imagine as the barbarians descended on Rome burning and pillaging centuries later they stayed their hand from the torch at the sight of the Pantheon. Even they could appreciate the excellence, the sheer majesty of her.

The Pantheon

Design Your Own Roman City

It is with utmost humility before your divine majesty, Imperator Augustus, that I present before you these plans for a new Forum for the town of Luna. As I bear witness, your great building program has turned Rome into a symbol of greatness for the world to observe and you have instructed humble servants such as I to share the greatness of Rome throughout the provinces. Luna indeed, is a fine beneficiary of your benevolence for our fellow citizens diligently oversee the quarrying of the finest marble in service of the Republic.

 

The selection of a very healthy site is proposed, elevated from the river Macra, away from the marshes, closer to the marble quarries. Much thought was also given to the dangers of unfavorable winds from the sea and mountains. The Decumanus Maximus has been laid from Solanvs (east) to Favonivs (west), granting access to the forum through the precinct wall whilst the Cardo Maximus runs from Septentrio (north) to Avster (south) and lead to Suburbia. Concerning materials for the building works the province is richly blessed with cypress and fir producing timbers felled in autumn, suitable clays for brick making and the finest marble for the cooking of lime. Just the pit sand of Baiae is lacking for the Opus Reticulatum and

Caementicium (concrete) works should your excellence deems these plans worthy of your patronage.

Mercury has indeed blessed our people with a fine economy so a prostyle, tetrastyle, pseudoperipteral Templum to honor him is raised upon a grand Podium against the precinct wall of the Forum manifesting the symmetry of god and man, duly proportioned in its whole as in its members, of the Ionic order as befits the statesman of the gods. I have taken note in its placement the wise observations of your servant Vitruvius, "the temple and the statue placed in the cella face the western quarter of the sky. This will enable those who approach the altar with offerings or sacrifices to face the direction of the sunrise in facing the statue in the temple, and thus those who are undertaking vows look toward the quarter from which the sun comes forth, and likewise the statues themselves appear to be coming forth out of the east to look upon them as they pray and sacrifice."

The Basilica adjoins the Forum, has its breadth exposed to the southern sun and its entrance situated to avoid a direct wind, a suitable orientation so that the discomforts of inclement weather will in no way hinder the matters of the Republic. For the citizens both a Theatrum and Thermae has been included. The theater follows the Greek model of concentric circles as the wave of the voice like the wave of water emanates in similar fashion while a vaulted passage allow the Decumanus to pass through. The Palaestra and Natatio provide for vigorous exercise, Apodyteria for changing, and the requisite Tepidaria, Caldaria, and Frigidaria.

May the gods continue to bless your valor and noble policies.
Your humblest servant Marcus Julius Patricius

DCCLXVI  (14 C.E.)


Contributed by Patrick Webb 

Roman Architecture: Weeks 1 & 2

Temple of Portunus

I signed up last autumn for an online course from Yale University Department of Classics on Roman Architecture. To my pleasant surprise its really fabulous. There is either a free option or $50 if you want to receive a certificate upon completion. Basically, it is an opportunity to virtually participate in a 3 credit hour Spring semester course, including some fantastic forum discussions with on site students and teaching assistants as well as moderators and online students around the world. There are lectures, homework, exams, the full experience of which I would like to share some of it with you!

Early Rome

When Rome was founded in the 8th century B.C.E., the Etruscans were still the most dominant culture on the peninsula, based out of Tuscany to the north. Before long the Greeks would begin to establish colonies to the south in Nea Polis (Naples) and on Sicily. The Romans were influenced by both cultures yet established themselves as unique. One way the Romans distinguished themselves was in their early temple architecture. We'll take the well preserved 1^st century example of the Temple of Portunus on the Tiber river to illustrate this point.

Temple of Portunus plan

Etruscan temples were typically a masonry structure fronted by deep porticoes, sitting on high podiums, with a single stair oriented to a dominant façade. These features are often preserved by the Romans; however, the tripartite cella and a rather simple 'Tuscan' order of wood construction that allowed for wide intercolumniation typical of Etruscan design was eventually rejected.

Tetrastyle façade, Ionic order

Greek temples used the Doric or Ionic order, featured a single cella, and had narrower intercolumniation that was peripteral, in other words having supporting columns going around the entire temple. The Romans worked out a compromise, incorporating elements of both styles resulting in a temple design that was more Etruscan in plan but featured peripteral, engaged columns or pilasters resembling Greek prototypes in elevation.

Does New Technology Lead to Revolution or Revolution to New Technology?

Our initial assignment was to write a short essay considering whether the discovery of a new technology leads to the creation of new forms or conversely whether the desire to express something in a different way leads to the invention of a new medium. Below was my response:

I would venture that the modern Western perspective of the role technology in architecture and culture is fundamentally different than that of the Ancient Romans.

Illinois Institute of Technology
S.R. Crown Hall

A principal leader of the Modernist architectural movement, Mies van der Rohe, emphatically declared at an address in celebration of the addition to the Institute of Design to Illinois Institute of Technology that “Architecture depends on its time”, going on to state that his real hope would be that architecture and technology would “grow together, that someday the one be the expression of the other”. Certainly in his own work and teaching, Mies was a proponent of using technology (specifically modern concrete and steel) as a driving force in pushing the limits of structural possibility.

Sanctuary of:
Jupiter Anxur
1st century B.C.E.

 Everything I have studied and come to  understand of Roman architecture and culture has led me to the conclusion, that by contrast, the Romans understood architecture not as a temporal phenomenon but a locational one. That “locus” was Rome, in the sense of an actual place, likewise in the sense of a powerful culture. The use of technological innovations such as the arch, vault, dome and Roman concrete served as a physical representation of their profound sense of history and identity. If there was a revolution, it did not manifest itself as a radical rejection of historical precedent. Rather, what we see from the Romans is a deliberate, measured, incremental sophistication expanded upon over centuries, of which we today can appreciate as a harmonious legacy.




Contributed by Patrick Webb

Plaster Word of the Day; 21 - 30

CLAY

The rebel Titan Prometheus was said to have fashioned man from clay. The Jewish, Christian and Islamic tradition all attest that the first man Adam (whose name means red earth) was likewise a divine result of breathing life into clay.

Mastery of clay is in fact integrally associated with civilization itself, at the heart of what separates the man from the beasts. Clay bricks and plasters permitted man to raise his first shelters and establish his first cities. Clay and earth continue to be the primary building materials worldwide.

Modern, Western society has eschewed clay and earth as a primitive medium in favour of high embodied energy materials and industrialized systems. However, we may share father Adam’s punishment for our transgression, “from dust you came…unto dust you will return.”

BINDERS

Photo courtesy of Plâtres Vieujot

‘Binders’ are the fine materials in a plaster that undergo a physical and usually a chemical change to ‘bind’ the plaster together in the setting.

Clay binders arrange themselves in tetrahedral sheets or ‘platelets’ a purely physical change.
By contrast, for gypsum and lime based plasters the binding action is accomplished by interlocking crystal formation, both a physical and chemical change.

COMPO

‘Compo’ really short for “Composition Plaster’, is a material and technique developed by the French in the late Baroque and very much associated with the Rococo period.

Various proprietary recipes are typically some mix of pine rosin, plaster of Paris, linseed oil, turpentine and the key ingredient rabbit skin glue. The key properties of the resulting mix is a flexible yet strong medium that captures fine details and will adhere to both plaster and wood.

LATH

Photo courtesy of Plâtres Vieujot

A latticed background of wood or metal for the support of plaster, most often over a timber frame backgroun. The penetrations or separation of the lath are so spaced to allow a portion of the plaster to fall behind and form a ‘key’ upon setting.

Although expanded steel is the most common lath system today because of ease of manufacture and installation, a quality wood lath such as chestnut produces a system that can endure for centuries, even through several plaster replacements.

 

DOUBLE-BACK, SWEET COAT


This technique of applying fresh plaster onto still moist plaster can be very useful for controlling the total thickness of a finish coat.

Because the initial coat retains moisture there is less suction thus reducing movement, avoiding ‘cold joints’ and facilitating a smooth finish. Very little plaster is used for this coat; instead the 'sweet coat' plaster acts more as a lubricant to level and close the surface.

SOAP

As plasters remain absorbent, topcoats are often used to provide some stain resistance especially in interiors. Traditionally in Europe natural soaps were preferred over waxes. The main reason is that unlike a wax which rests as a film on the surface, these soaps penetrate into or ‘impregnate’ the pores of the plaster.

If freshly applied over a lime plaster a chemical reaction takes place, ‘saponification’. The resulting reaction of the alkali soap with the fresh hydrated lime produces a thin protective layer of calcium stearates (i.e. soap scum) which is highly resistant to liquids and at that concentration remains transparent.

BLACK SOAP, SAVON NOIR

The traditional natural soap of North Africa based on raw olive oil and potash (potassium salts, mostly potassium carbonate).

WHITE SOAP, SAVON DE MARSEILLE

The traditional natural soap of Southern France based on palm kernel oil using lye and soda ash as the alkalizing agents to maintain its whiteness.

HEMP LIME

The woody inner core of the hemp plant, called the shiv or hurd, has excellent binding as well as thermal

Photo courtesy of Vicat

insulating properties. About 20 years ago the French began mixing Hemp shiv as an aggregate with NHL or Natural Cement and pouring into forms to create monolithic substrates.

After a quick setting, the low embodied energy, insulating building substrate is ready to plaster inside and out. The British and Irish soon followed suit and the technique is gaining notoriety in the US and Canada. 

NATURAL CEMENT, ROMAN CEMENT

‘Natural Cement’ is an eminently hydraulic lime that is baked from clayey marls that have an high alumina content in addition to active silicas. The Romans exploited hydraulic lime deposits and would sometimes combine them with pozzolans to increase the hydraulic setting action even further.

With properties of a rapid set, self binding and high resistance to salt attack, natural cements are used for exterior statuary, run mouldings and as an accelerator for natural hydraulic limes. 

Photo courtesy of Vicat

Contributed by Patrick Webb  

Plaster as an Architectural Specification

From its origin as a British colony the United States inherited a fully developed plaster tradition that would

East Room, White House

circa 1951

expand considerably from the mid-19^th century until the 1940s. The fine craftsmanship can still be enjoyed in public settings such as period railway stations, banks, courthouses and capitals across the nation. Many fine plaster ceilings enduringly grace private residences in historic neighborhoods such as Brooklyn Heights and Peninsular Charleston.

However, in the decades following World War II plaster ceased being specified and plastering rapidly diminished as a trade. What happened? Two distinct movements figured prominently: the ascendency of architectural Modernism and cheap, industrialized residential construction.

Pre-fabricated home. Levittown, PA

circa 1951

Modernist architectural programs were no longer teaching the traditional language of ornament. By contrast, students were learning that ornament was born of a superstitious and deceitful past, craft was a criminal enterprise injurious to the human spirit and that industry and technology were to be embraced as the basis for a new, purer aesthetic. At the same time, prefabricated temporary housing developed for the military during the war was being modified by developers for residential use. Factory produced construction systems were designed to be assembled by unskilled, replaceable laborers. Part of the package was to replace traditional plastering with nascent “dry” wall systems. By the 1980s there were practically no traditional plaster apprenticeship programs, little opportunity for training, by all appearances the trade had died.

Grand Central Station, NYC

With the destruction of New York's Penn Station in 1963 and the proposed destruction of Grand Central Station in the 1970s, an architectural consciousness began to arise among the public at large, a widespread awareness of how much of value from our traditions was being lost. This coalesced both into an historical preservation movement and a renewed interest in traditional architectural design. By the 1990s plaster was being once again, if cautiously, specified in new construction. For several generations of architects plaster has become somewhat of a mystery not understood or taught by architectural programs. Many architects would like to specify plaster, yet being unfamiliar with the medium are concerned with exposing themselves to risk or appearing irresponsible with their client's budget. Let's see if we can't ease that trepidation by considering some of plaster's strengths and its most practical, effective uses in contemporary architectural specification.

Traditional Plastering

Gypsum drywall has largely displaced traditional plastering for interior walls and ceilings. Many homeowners are surprised to discover that the vast majority of the gypsum used for drywall is the waste byproduct of coal-fired power plants pollution control systems. This is in contrast to gypsum, lime and other plaster binder materials that are mined from naturally occurring deposits. I would like to highlight a few specifications where traditional plasters should be considered as a practical alternative to drywall:

1. Monolithic substrates
2. Curvilinear surfaces
3. High durability

Plaster applied directly to

straw bale

Monolithic substrates (as opposed to cavity wall systems) are solid substrates, common examples being brick masonry, cast concrete or CMU blocks. The maturing natural building market also typically use monolithic substrates such as straw bale, adobe and compressed earth blocks, cob, rammed earth, hemp lime, etc. Exterior plaster or “stucco” will invariably be a practical solution in the exterior. However, interior plaster applied directly to the substrate is likewise a practical alternative to furring strips and drywall. With a carefully selected binder (clay, gypsum, lime, hydraulic lime or cement) a plaster can be formulated that closely matches the thermal, expansive, permeability and other characteristics of the substrate resulting in a far superior surface that is completely integrated into the substrate.

Running a barrel vault in place

courtesy of Sloan Houser

Curvilinear surfaces which may include walls but are often horizontal ceiling surface such as domes, vaults

and the underside of staircases are a logical consideration for plaster specification. I've been on many projects where vaults are painstakingly framed out with what is commonly called “ship hull framing” to receive multiple layers of ¼” drywall that has to be cut into small strips, soaked and scored in the back to adjust to the curvature. This is completely unnecessary and an inferior construction to traditional plaster over lath, requiring only nominal framing.

Courtesy of Louvre Museum
and Plâtres Vieujot

High impact and abrasion resistance may not be expectations of walls surfaces for a residential home; however, for commercial and institutional specifications of hotels, museums, shopping centers, universities, airports and similar settings, long term durability and low maintenance are concerns to balance against initial cost. Gypsum, lime and cement plasters are often prudent investments that can also provide a pleasing aesthetic.

Cast Mouldings and Ornament

As the millwork industry became increasingly sophisticated, soft “paint grade” woods such as pine and poplar began to displace plaster as the economic plain moulding specification. The integration of ornament enrichment into mouldings slowed this transition until ornament itself was largely stripped from architectural design in the mid-20^th century. Nevertheless, there are many strong arguments for specifying plaster mouldings with the following specifications often being competitive or less expensive.

1. Medium to large curvilinear profiles
2. Non-radial curvilinear profiles
3. Large, complex crown mouldings
4. Curvilinear oriented mouldings
5. Ornament
6. Low maintenance

Image courtesy of
Palladio Mouldings

Straight mouldings can be produced just fine in plaster but it excels like no other medium in being able to contour to curvilinear shapes. I say curvilinear as opposed to radial because plaster is not constrained physically or economically to arcs of circles but can readily accommodate ellipses, hyperbolae, or free formed curves. The process helps to explain this property. The first step in creating a plaster moulding is hand-cutting a reverse metal profile from a template. The profile is mounted on a jig and the plaster is built up in successive layers on a table or ramp. For plaster it matters very little if the profile is large or small, very complex or composed of non-radial curvilinear elements. In fact, the moulding itself can be curvilinear such as vertically for architraves surrounding arches, or horizontally as for moulding applied against a curvilinear surface or even complex helix shapes as sometimes encountered in the stringers of descending staircases.

 

Students learn to sculpt, cast and apply
plaster ornament at the
American College of the Building Arts

With a return to interest in traditional architecture there has been a corresponding interest in ornamentation. As with plaster moulding profiles, the work of plaster ornamentation is by hand so there are no mechanical constraints. Often much time is invested in a single model of high quality from which a mould is produced. Plaster is an inexpensive material and multiple casts can be easily and economically produced. The more detailed the enrichment and the more units produced the more value can be attained with ornamentation.

Particularly when large or ornate mouldings are specified I have found clients concerned about maintenance becoming an issue. The coefficient of expansion of soft woods is relatively high with changes of temperature and especially humidity. This is exacerbated by the reality that wood mouldings are typically affixed mechanically against drywall or plaster materials that have a very low coefficient of expansion. The wood moulding moves, the wall does not and cracks develop quickly between the disparate materials that are either addressed with caulk or lived with. Alternatively, plaster mouldings are affixed with plaster to a plaster (or drywall) substrate. The result is a monolithic system, the bond is so strong that the mouldings literally become a part of the wall. Most plasterers will guarantee that aside from structural movement their work will not crack, ever.

This article is a brief summary of a subject that can become very specific for a given project. As a technical consultant for plaster materials and application, I provide services to architects helping them properly specify plaster and plaster systems. I also work with plaster contractors providing training and onsite consultation services as needed.

Contributed by Patrick Webb

Moulding Theory

Image courtesy of Vicat

The art of plastering is itself divided into two major fields of employ. Rendering is fundamental. A plaster apprentice first learns to ‘tend’, to prepare various binders such as gypsum, lime or cement into a workable plaster mix. As he progresses, he then learns how to ‘square’ a room, establishing centerlines, benchmarks and grounds. His education culminates in mastering the art of rendering plaster, applying plaster in successive coats until he achieves a smooth and planar surface.

Many plasterers make a good living with rendering skills alone. However, for the ambitious, once mastery of rendering has been achieved a plasterer may progress unto run moulding work. As is the case with all moulding mediums, plaster moulding is an art strongly allied to the field of architecture. A number of treatises, books and papers have been published from the Renaissance through the 20^th century on the theory of moulding design.

I will attempt to briefly present three ways of considering moulding design using metaphors of language: Vocabulary, Grammar, and Composition. As is the case with language, we can think of each section as a progression building towards higher levels of sophistication.

Vocabulary

In language vocabulary is the set of words that are familiar to a person or group of persons.

It is a fundamental of speech and communication. To create intelligible mouldings architects and artisans also have need for a common vocabulary.

The vocabulary of mouldings can be defined as the most basic elements found within a moulding. The shape of a given moulding is determined by its profile. In the case of plaster this profile is in the form of a knife that ‘cuts’ the hardening plaster. A given profile will contain several ‘elements’ or individual shapes that make up the profile. These individual shapes each have a specific geometry that can be identified. Our moulding vocabulary can likewise be thought of as the pure geometric forms found within a moulding.

We can group individual elements in a profile by their geometry. Below are a few examples sorted under the four major geometries:

Image courtesy of Palladio Mouldings

Straight: fillet, fascia, chamfer

Concave: cavetto, scotia, congé

Convex: ovolo, torus, astragal

Compound: cyma recta, cyma reversa, beak

Grammar

Every language needs rules, structure, otherwise known as grammar. Just as individual words or vocabulary perform a function (noun, verb adjective, etc.) within a sentence, individual moulding elements manifest an architectural function within a profile. Let’s consider each of the five of the principal architectural functions of mouldings individually.

Terminating: cavetto, cyma recta

Terminating elements are often found at the top of a cornice or other crowning feature. Because most of its form is void, it conveys lightness but an inability to support a load so therefore is not generally appropriate lower in a profile.

Supporting: ovolo, echinus

In direct contrast to the aforementioned terminating elements are supporting elements. The robust, sturdy shapes of these elements imply a capacity to support significant weight above it. Supporting elements are prominently featured as bed mouldings where they appear to support a projecting crown.

Binding: torus, thumb, astragal

As the name implies binding elements encircle an object as if it were holding it together. Various half round elements such as tori or astragals are commonly found at necks and bases of columns.

Separating: bead, fillet, scotia

Separating elements typically are smaller in scale to binding elements. As such, beads and fillets create division and clarify transitions from one larger element to the next.

Prone: cavetto, cyma reversa

Transitions from vertical wall surfaces to horizontal floor surfaces indicate a transfer of weight. Prone mouldings can simultaneously provide a graceful translation from one vertical plane to the next such as the bottom of a wall or column to the top of a base or plinth.

running a moulding on a bench

Composition

Upon mastery of vocabulary and grammar we have all the tools necessary to compose a moulding profile or even an entire elevation. Of course, we’re faced with the traditional challenges of any author of creating an intriguing story! Next are a few principles to keep in minding in moulding composition.

Harmony is very important both within a moulding and throughout an entire elevation. One of the most harmonizing factors is to maintain a common facial angle common to all mouldings. In Roman and Renaissance architecture 45° was a common angle whereas 60° was used more often by the ancient Greeks. Too much harmony, such as repeating the same elements at the same scale, can lead to monotony.

Rhythm can provide welcome contrast. Alternating straight and curved elements is one way of providing rhythm. Contrasting concave and convex curves is also very effective. Radial curves provide a very even gradation of shadow whereas curves of conic sections (parabolae, hyperbolae and ellipses) provide sharper transitions and more contrast. For many theorists the study of the shadow created is more important than the profile itself.

Dominance is a principle that can define the feel of a moulding, elevation or an entire building. The addition of 'ears' or an over door to an entry can indicate its hierarchy over lesser doorways. Dominance can also be achieved by use of scale, exaggerating a supporting or terminating element throughout the composition i.e., to establish an overall feeling of delicacy or ruggedness.

A Classical Example

The Attic Base is the most used column base in Classical and Gothic architecture and is found in other vernacular architectural styles around the world. Let’s break it down to its constituent elements and see how much of what we have previously considered applies to the Attic base.

The vocabulary or individual elements of the Attic Base and their grammatical role are as follows from top to bottom:

Attic Base

fillet – separating

torus – binding

fillet – separating

scotia – separating/prone

fillet – separating

torus – binding

The composition manifests principles of harmony, rhythm and dominance. Let’s break it down:

All three fillets are the same height creating a harmonious relation. Also, the tori are both perfect half rounds although by being of different scales they avoid monotony.

The two middle fillets combine with the scotia to provide contrast against the tori establishing a rhythm of binding, separating, binding. The scotia is slightly prone allowing the bottom torus to be larger.

The two tori definitely dominate the overall composition, firmly establishing the Attic Base as a binding moulding.

Conclusion

This post is obviously a brief review of a very involved study refined over thousands of years. However, even a basic understanding of vocabulary, grammar and composition will allow anyone to ‘read’ and appreciate many of the great architectural works of Western civilization.

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Contributed by Patrick Webb