|Cliff Palace, Mesa Verde|
Pre-Colonial Earthen Plaster
|Navajo Hogan, Monument Valley|
One of the building techniques existing throughout North America prior to European settlement was the earth lodge, a central space with wattle and daub walls covered with a dome roof, having a smoke hole at the apex. The Navajo of the dessert Southwest developed a variation of the earth lodge called a “hogan”, featuring earthen floors and timber walls packed with a thick, clay-rich earthen plaster on the exterior. Hogans are extremely energy efficient benefiting from natural ventilation and evaporative cooling during hot days whereas just a small fire is needed to take advantage of the thermal mass properties of the earthen plaster, maintaining the interior warm during long winters and cold nights.
Structures constructed entirely of clay-rich subsoil reinforced with straw were also common, essentially forming a plaster building. One method was to shutter the mixture between boards with a light tamping, something between a rammed earth and a cob technique. Alternatively, the mixture might be formed into rectangular "adobes", left to dry and used as mud bricks bonded with an earthen mortar. For both methods the surface would be rendered with an earthen plaster and finished with an "aliz" or clay slip that would be reapplied annually for maintenance. In a region with little rainfall and scant resources for fuel, hogans and adobe structures are comfortable, healthy and efficient.
|San Miguel Mission|
|Castillo de San Marcos|
On the East coast and in the Caribbean the Spanish utilized lime for mortar and for plasters. With plenty of wood for fuel and oyster shells readily available, lime was easy to produce. The Spanish already had a tradition of producing lime plaster from the continent and it was a more durable material for the subtropical, wet climate. Both the 16th century Castillo San Felipe del Morro in San Juan, Puerto Rico and the 17th century Castillo de San Marcos in St. Augustine, Florida are well preserved examples of the durability of limestone construction utilizing lime mortars. The fort would have been a brilliant white when constructed. Some lime plaster of the Castillo de San Marcos is still visible.
|St. Paul’s Chapel, NYC circa 1764|
|Kenmore Plantation, circa 1776|
Meanwhile in the agricultural South and mid-Atlantic, crops such as rice, tobacco and indigo were generating incredible revenues. Wealthy landowners began to construct palatial plantations modeled after English country houses again in a Palladian style. Interior details including ornamental plaster ceilings were a symbol of wealth, status and cultural sophistication. The Kenmore plantation in Fredericksburg, Virginia is one of the best preserved examples featuring room after room of highly ornamented neoclassical plaster ceilings.
I last mentioned that this was to be the concluding article in the series. However, upon preparing for this article it became evident that there is a larger story to tell in the United States. Next time we'll continue by considering our own national history of plaster from the Federal period into the 20th century.
Contributed by Patrick Webb