What is Venetian Plaster?
Originating in antiquity, Italian Plasters came into prominence during the Renaissance in Venice and were re-discovered by Carlos Scarpa in the 20th Century. The term “Venetian Plaster” refers to “Stucco Veneziano,” or “plaster in the style of Venice.”
Stucco Veneziano is a multi-layered, integrally colored lime based material that is known for its highly polished surface and luxuriously smooth feel.
Stucco Veneziano is one of many Italian Artisan Plasters. The term “Venetian Plaster” is sometimes used domestically to describe integrally colored plaster, like Stucco Veneziano, but at other times, any of the entire range of Italian or Artisan Plaster finishes.
Traditional Italian Plasters are comprised of processed limestone, marble aggregates, and pigments. Most modern versions of Italian Plasters, even those imported from Europe, also blend these mineral ingredients with polymers to make the application process easier for lesser skilled artisans.
While products bearing the term “Venetian Plaster” are available at building supply and paint stores, they are predominantly, if not entirely, synthetic materials, with little or no lime or marble ingredients. Because they are comprised of polymers and fillers, they look and feel more like plastic than proper plasters. Additionally, integrally colored gypsum plaster, a.k.a. veneer plaster, is also sometimes mistakenly referred to as “Venetian Plaster.” These synthetic or substitute materials may appear to be more cost effective alternatives, but in fact bring a range of concerning issues with them, like aging, cracking, durability, and aesthetic problems.
Is “Venetian Plaster” the same as “Veneer Plaster”
Because typically a veneer is a thin layer of precious material applied to the surface of a more common substrate material, Venetian and Artisan Plasters could fairly be referred to as a veneer.
However, it is confusing to refer to Venetian Plaster as a veneer plaster, as “Veneer Plaster” is the proper name of a domestic gypsum plaster system, also called “thin-wall,” “hard-troweled plaster,” or by the product names “Diamond” and “Kal-Kote.” All of these terms refer to general production-grade gypsum plaster finishes, which are applied over a sheetrock product with special paper surface called “Blue Board”.
Gypsum plaster—mixed with low-grade lime—is the material originally used to plaster walls before drywall. Throughout its history, gypsum plaster surfaces were mostly painted over after installation. However, with the rise in popularity of Venetian Plaster, these finishes are being done with integrated color, in an attempt to create cheaper colored-plaster finishes.
Gypsum plaster has a high compressive strength, which gives it a hard surface. However, with this surface strength, gypsum also tends to be more brittle and prone to cracking. Gypsum lacks dynamic light-reflection properties, resulting in pasty, flat, or “dead” colors. Moreover, because gypsum plaster was not originally designed to be a colored-finish material, it is manufactured according to the less stringent demands of common building materials, thus potentially having color and mottling consistency issues. Additionally, being primarily calcium sulfate, gypsum is too water soluble for exterior use, or for wet areas, like bathrooms, kitchens, or showers.
Does it matter who installs the plaster?
Far and away the most important aspect of any Artisanal Plaster finish is who does the actual plastering.
Many contractors and design professionals assume that any competent plasterer could be contracted to install any Artisan plaster on any given project. However, because plaster is a hand-done finish, the contractor matters more than the materials or finish selection.
Plaster finishes are highly dependent upon timing and the finesse of the applicator’s hand. Applied in various layers the plaster is compressed and burnished, slowly and repeatedly, at precisely the right time(s), until the process is complete. The type and degree of mottling, sheen, and surface quality is dependent upon the finisher’s hand.
Any missteps at any point along the way, however small, will readily show in the finished product.
All of the steps and timing involved are different for every plaster finish, so the plasterers need to be well practiced at any finish they are going to attempt. Most plasterers are only trained in production finishes, that emphasize production speed, as opposed to finesse. Artisan plaster finishes are just the opposite, and are all about finesse
Unlike paint chips, that can be specified to many competent painters, plaster samples should be made by the applicator. As such, one should not assume that any given plasterer can perform any given Artisan finish, or that they would have access to the proper materials. We highly recommend working with a single plaster contractor from the beginning of the sample process through to the installation to ensure that the project matches the approved sample in terms of being the correct material, color, mottling, and sheen.
Some of the finishes we do are proprietary, or very nearly, as we have researched the historical recipes, sourced the materials, and blended them accordingly. In such cases, we do not sell materials to other plaster contractors, nor train them.
Does my plaster need to be sealed?
Because all plaster surfaces are porous, one must consider the environmental and lifestyle factors (like, dogs, kids, wet areas, kitchens, etc.) to determine if sealing is necessary. The more likely it is that the plaster is going to come into contact with staining agents, the more likely it is that the plaster should be protected.
We will discuss sealing with every client, as well as the aspects and limitations of the various sealer options, during the process of finalizing finish and color specifications.
Thom Bruce Studios 