What is Italian decorative plaster?

Italian decorative plaster is generally a thin veneer of slaked lime putty mixed with marble, quartz or kaolin, and colored with pigment. The plaster is applied in a variety of ways to produce elegantly mottled wall and ceiling treatments especially those found in what is now northern Italy. The use of plaster in this way has been evident throughout that area for the entire last millennium.

History of Venetian Plaster

Lime plaster is among the oldest building materials known to humankind; there is evidence of its use dating as far back as 9,500 years in the area of present-day Jordan. Later the Romans were known to use it mixed with marble dust as a fine application over a coarser lime and sand aggregate, not dissimilar to the technique used today by us. Continued use of slaked lime putty existed throughout the middle ages. Documented evidence of the Mantovano finish, resurrected by, and now reliably produced only by the Safra Co. of Villa Franca, Italy, dates to circa 1100AD. During the Renaissance in the mid 16 th century the Marmorino finish was reintroduced in Venice largely due to the efforts of Andrea Palladio and used externally over civil plaster masonry. By the 17th century many types of interior plasters flourished, the most notable is the highly polished Stucco Veneziano found in the palaces and Villas of 16th and 17th century Most Serene Republic of Venice.

Nomenclature of Italian Plasters

There is no standardized naming system applied to the manufacturing of Italian decorative plasters. Names may refer to composition, style, or may be merely branding, or some combination of the three. Further confusion comes from the vernacular use of the term "Venetian" to refer to any and all types and techniques of decorative plaster work.

In the USA, Venetian plaster includes both pure slaked lime, and lime plasters modified with acrylic polymers. The modified plasters tend to be very durable but one should beware some "Venetians" available at large discount home improvement stores or paint stores as these may have little to do with actual Italian plaster. In some cases the product may have no lime or marble whatsoever, and even the term plaster may be a misnomer. In Italy, Venetian or Stucco Veneziano is one particular kind of plaster and application technique only. No true Italian plaster requires wax or sealer for reasons other than embellishment.


There is no unmodified Venetian plaster manufactured in the USA. To our knowledge the only pure slaked lime unmodified Italian plaster available in the USA is imported from Safra Sp.A. and is sold only to those certified by their representative in the USA.

The process of making the plaster involves cooking the mined limestone (calcium carbonate) in ovens or kilns at between 850-1300 degrees Celsius, producing calcium oxide (quicklime), which is then slaked with water to produce calcium hydroxide. The mixture is then left to mature or age. Roman law required the slaked lime to be aged for a minimum of 3 years. This process is called hydration. The result is lime putty or grasselo, also known as non-hydraulic (it will not cure under water), hydrated, because the lime is chemically bound to the water, or aerial lime because it requires exposure to air to cure. Next, the slaked lime putty is filtered and mixed with marble flour, kaolin, marble dust or quartz to produce a variety of decorative plasters. Atmospheric carbon dioxide cures the lime putty after application by reacting with it to produce calcium carbonate, thereby returning it to its original state and completing the cycle. This final process is called carbonation, and takes some weeks to complete.

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