Venetian Plaster Elegance
Venetian Plaster can be made from different ingredients depending on the desired finish; however, the traditional makeup of Venetian Plaster is little more than limestone and water. Limestone is mixed with water to create a putty-like substance known as lime plaster, which is the core of what we now think of as Venetian Plaster.
Over time, additional ingredients would be added to the mix to create different finishes. For example, marble dust is added when the desired finish is that of a marble-like surface, and river sand can be added when a more earthy look is desired.
Though not part of the ingredients of the plaster itself, waxes and oils are also used in the finishing process to create different looks and tactile textures. For example, certain waxes can be used to bring the surface of Venetian Plaster to glass-like smoothness. Oils can be used to bring out the colours of the plaster, making the contrast of the patterns more pronounced.
It is worth noting that the alternative forms of Venetian Plaster—the variants that have aggregates like marble dust mixed in—have their own names, and are often considered separate from Venetian Plaster as far as naming goes. We will take a look at these different types in this article, but as a general all-purpose answer to the question of what Venetian Plaster is made of—lime and water.
Properties of Venetian Plaster
Venetian Plaster has several desirable properties when compared to more modern alternatives, mostly thanks to its use of lime slake. Once set, the lime putty that has been mixed essentially turns back into limestone.
This makes the plaster naturally resistant to mould and mildew, as well as being naturally anti-bacterial. It is also waterproof in some styles, or with the appropriate treatment, making it just as suitable for wet rooms like a bathroom as it is for hallways and ornate rooms.
Visually, Venetian Plaster has a degree of depth and movement to it that is not possible with paint. The appearance can be enhanced by the use of waxes and oils, which will have varying effects on the colours and patterns in the plaster.
Modern Venetian Plaster Ingredients
As the years—and technology—have progressed, other ingredients have been introduced into the mix. Natural lime-based plaster is much as we mentioned above and contains little more than lime slake, water, and any aggregates necessary for the desired finish. This form of Venetian Plaster can be very labour intensive, as it will require many coats to get the right look. It is suitable for both interior and exterior surfaces.
More recently, acrylic-based plaster has become common for outdoor use. This kind of Venetian Plaster is less labour intensive than the natural lime variant. Alternatively, there is a gypsum-based alternative. This variant is far more cost-effective than lime or acrylic-based, both in terms of material costs and how labour intensive it is, but it is also less durable than those alternatives, making it more of an interior-only option.
Different Styles of Venetian Plaster
As we mentioned, there are different kinds of plaster that are loosely considered to be Venetian Plaster, while also existing separately as their own thing. Here we will look at a couple of the more common of those different kinds of plaster, as well as looking at what goes into making them.
Marmorino uses the same basic ingredients of lime slake and water as regular Venetian Plaster, but with the addition of crushed marble aggregate. A colour tint can also be added to the ingredients to achieve a wide range of different colours in the finished surface.
This style of plaster is on the higher end of the scale when it comes to expense, and the skill level needed to be able to achieve a good final result. Speaking of that final result, if it is a marble-like finish that is required, this is the plaster for that.
Marmorino can achieve a look that is almost indistinguishable from real marble—certainly to the untrained eye. Interestingly, despite being thought of as a type of Venetian Plaster, Marmorino predates it, being common as far back as the height of the Roman Empire. However, it was made popular once more during the Renaissance.
Tonachino plaster makes use of river sand, rather than marble dust, and is more suitable has a better filling ability than Marmorino. The finished look, while still very attractive, is somewhat more earthy than the marble-like finish of Marmorino.
Without additional treatment, it can feel velvety to touch and has a warm, matt finish. This style of plaster is excellent for situations where the beauty of Venetian Plaster is desired, but the glossy marble of Marmorino is perhaps considered a little too much.
Why Choose Venetian Plaster?
While it is true that there are plenty of compelling alternatives—such as stucco concrete, microcement, and even regular plaster and paint—there is something alluring about the iridescence of Venetian Plaster. The three-dimensional depth that is conveyed by the different layers is something that can only be matched by the very minerals the plaster is mimicking.
Of course, this kind of plaster is not perfect for all situations. It is durable and hard-wearing, but it is not very flexible. Given that a smooth, unbroken finish is part of the aesthetic, it would not make sense to use Venetian Plaster in a setting where it would need to be broken up to account for flex and movement of the structure. In these cases, something like microcement—which is considerably more flexible than plaster—would be more appropriate.
Venetian Plaster is also considerably more expensive than the alternatives, making it a less attractive prospect if the situation does not call for this kind of look specifically.
Still, the naturally anti-bacterial and mildew resistant properties of the plaster should not be discounted when weighing up the worth of this kind of plaster for a project. Regular plaster will typically need additional treatment to achieve the same kind of properties, and will not look nearly as attractive once finished. Then again, if looks aren’t important, or if it is likely you will be painting over the surface, Venetian Plaster is definitely not the right choice.