Venetian plaster is a technique for applying plaster to walls, raised or curved surfaces, and ceilings to give it a heightened stucco-like appearance and texture. The method was perfected by craftsmen in 15th-century Rome around the region of Venice, Italy, from which it gets its name. It has remained popular into 2011 and refinements in the technique and plaster compounds that are used have made it a process that is accessible to any contemporary building or remodeling project. Changes in the technique have also adapted it for its most frequent use in modern times, which is to apply it to flat drywall surfaces.
The primary method for applying Venetian plaster to a wall involves using a trowel, putty knife, or spatula to apply the plaster in thin, successive layers that are allowed to individually dry before the next layer is added. The initial layers need to be thinner and smoother than later layers so that the plaster will adhere to the wall effectively over time. As additional layers of Venetian plaster are applied, the objective is not to create a smooth surface, but to work patterns and textures into the plaster that are maintained after it has dried. A final thin layer of Venetian plaster is applied to seal the surface imperfections, and, after this has dried, the surface is usually lightly sanded to polish it and remove any imperfections that could lead to chipping or cracking. The end result is a semi-gloss marbleizing effect where the plaster has subtle color and texture variations that change with lighting and different angles of view.
The use of the Venetian plaster technique whether for a wall finish or ceiling finish can also involve the use of paint. Instead of or aside from using plaster, paint itself can be troweled onto the wall surface at a slight angle in successive layers, giving the final look one of texture and subtlety. Using paint will produce a finer surface than plaster due to its lower viscosity, and latex paints, which are thicker than enamel-based paints, tend to be more effective. A hybrid method includes applying Venetian plaster itself and then following up with a Venetian paint as a top coat, though some painting projects use an ordinary paint primer prior to applying the Venetian plaster technique with the paint. The more time that is spent working repeating patterns into the surface whether using paint or plaster, the better it will look when finished, and overall the appearance tends to be one of artificially aging the wall or ceiling surface.
Since the Venetian plaster technique has been practiced for over 500 years, several different branches of the method have formed with individual histories. The Marmorino look is based on a popular Renaissance design that used crushed marble and lime putty for surfaces which allowed for a wide range of color and texture mixes resembling the appearance of natural stone. Scagliola is another offshoot that is focused on sharper edges and inlays such as are seen in columns and sculptures, and it was a dominant form of stucco plastering in 17th-century Tuscany in west-central Italy.
Sgraffito most strongly resembles typical Venetian plastering in form, but is often used on ceramic pottery as well, and incorporates fine scratches into the surface. The use of Sgraffito is popular in African art and has been dominant in Europe since the 16th century. Tadelakt is another technique that is related to Venetian plaster methodology, and originated in the palaces of Morocco in northern Africa. The end result with Tadelakt is one of soft waves and flowing forms in the surface of a wall or ceiling like that of ocean patterns or growth patterns for trees and vines.