From The Art and Popular Culture Encyclopedia
In classical architecture rustication is an architectural feature that contrasts in texture with the smoothly finished, squared block masonry surfaces called ashlar, . Rusticated masonry is usually squared-off but left with a more or less rough outer surface and wide joints that emphasize the edges of each block. Rustication is often used to give visual weight to the ground floor in contrast to smooth ashlar above.
In variations of rustication the stone is left with a rough external surface, or rough shapes are drilled or chiselled in the somewhat smoothed face in a technique called "vermiculation" (vermiculate rustication). If deeply cut-back edges are worked only to the horizontal joints, with the appearance of the vertical joints being minimised, the resulting effect is known as banded rustication. In prismatic rustication, the blocks are dressed at an angle top and bottom and at each end, giving the effect of a prism.
Although rustication is known from a few buildings of Roman Antiquity, the method first became popular during the Renaissance, when the stone work of lower floors, and sometimes entire facades, of buildings were finished in this manner. Donato Bramante's Palazzo Caprini ("House of Raphael") in Rome provided a standard model, where the obvious strength of a blind arcade with emphatic voussoirs on the basement level gave reassuring support to the upper storey's paired columns standing on rusticated piers. The Palazzo Te in Mantua, and the Palazzo Strozzi in Florence are examples in which the entire facade is rusticated. In his Banqueting House, London (1619), Inigo Jones gave a lightly rusticated surface texture to emphasize the blocks on both storeys, and to unify them behind his orders of pilasters and columns.
The Mannerist architect Sebastiano Serlio and others of his generation enjoyed the play between rusticated and finished architectural elements. In the woodcut of a doorway from Serlio's 1537 treatise, the banded rustication of the wall is carried right across the attached column and the moldings of the doorway surround, binding together all the elements.
During the 18th century following the Palladian revival, rustication was widely used on the ground floors of large buildings, as its contrived appearance of simplicity and solidity contrasted well to the carved ornamental stonework and columns of the floors above. A ground floor with rustication, especially in an English mansion such as Kedleston Hall is sometimes referred to as the "rustic floor", in order to distinguish it from the piano nobile above.
Feigned rustication in wood construction
The appearance of rustication, creating a rough, unfinished stone-like suface, can be worked on a wooden exterior. This process became popular in 18th century New England to translate the features of Palladian architecture to the house-carpenter's idiom: in Virginia Monticello and Mount Vernon both made use of this technique. Mount Vernon in particular makes extensive use of feigned rustication and sanded paint and the original finished surfaces of several original planks still survive.
Rustication of a wooden exterior consists of three basic steps. First, the wood is cut, sanded and prepared with beveled grooves that make each plank appear as if it were a series of stone blocks. Second, the wood is painted with a thick coat of paint. Third, while the paint is still wet, sand is thrown or air blasted onto the planks until no more sand will stick. After the paint dries the plank is ready for use.