Rustication is a style of masonry which involves the use of large, rough blocks separated by deep joints. This technique can be seen in architectural stylings from a number of regions and periods. One classic use of rustication is in large buildings, where the first floor may be dressed with rusticated masonry, while upper floors use smooth dressed stone, also known as ashlar. This creates a marked visual contrast between the lower floor and upper stories.
There are a number of styles of rustication. In all cases, the style is meant to be big and bold, drawing attention to the rusticated stonework. The textured look can also give a building as a whole more texture and visual interest. Another advantage to using textured stone is that flaws are not as readily visible, because they are concealed by the irregularities of the stone.
In some cases, the outer face of rusticated stone is not dressed at all, but left coarse and rough. In prismatic rustication, the stone is dressed, but with intense angles which create the appearance of an exaggerated prism. With vermiculation, also known as vermiculate rustication, a smooth surface is roughened with tools which create an irregular appearance.
The depths of the joints between the stones can also vary. In some cases, the horizontal joins are exaggerated, with the vertical joints being minimized. Rusticated stone can also be integrated into a scheme with ashlar stonework; for example, pillars of rusticated stonework can be surrounded by flat expanses of smooth dressed stone to create a desired visual appearance of depth and texture. This technique can sometimes be used to cover up modifications to a structure.
Rustication can also involve the use of stonework with irregular joins, rather than a neat pattern of horizontal and vertical ones. This can be seen in some stone walls and on the ground floors of some structures. One advantage to this technique is that it allows people to use irregular-sized and shaped stones, rather than discarding them.
One doesn't have to use stone to achieve a rusticated look. In some regions, textured wood is used to create the appearance of rustication. The wood is finished and handled in a way which creates a rough, textured surface with deep joins, creating more visual interest. This trick was sometimes used in regions where stone suitable for building was expensive or difficult to obtain, allowing people to enjoy the appearance of rustication without the cost.