Ordinarily, we would like to answer any question posed by one of our posts at the top, and then go on to expand on our answer for those interested. We can’t do that here. The sheer variety of styles of Venetian Plaster makes it impossible to pick just one sealer as the best since the sealer is often a very active part of the look and feel of the finished product. We’re going to go out on a limb and recommend an olive soap wax; however, there is far more to this topic.
Of course, every sealant manufacturer will tell you that their product is the best, but that’s just marketing speak—it is their job to make you believe their product is the best.
That being said, just because we can’t definitively tell you which sealant is best for your Venetian Plaster doesn’t mean we can’t give you the information you need to decide for yourself. So keep reading, and we’ll delve a little deeper.
Different Types of Sealant for Venetian Plaster
There are a few options when it comes to the sealant, and we’re not just talking about brands. There are sealants that soak into the plaster and sealants that sit on top of it, natural sealants and synthetic sealants. These are not just cosmetic or personal preference choices; they actually affect how the plaster looks and feels when done. They can also change what the plaster can be used for. For example, if you want to have Venetian Plaster in your bathroom, you need to seal it in a way that is appropriate for use in a wet environment.
Waxing is the traditional method of sealing Venetian Plaster, with waxes like beeswax being used for hundreds of years. It is typically applied in much the same way that the plaster itself is applied, before being burnished and polished. The wax can be tinted to colour the plaster or left clear for a more natural look.
The finish itself can be glass-like in smoothness, or have more of a matt look and feel to it. To increase the glass-like effect of a polished wax finish, you can use an electric polisher to buff out the final coat.
Waxing is preferred by many because of its traditional roots and its organic nature. The plaster itself is a breathable material—being made from lime—so it feels right that it should be finished with an organic sealer in the form of wax.
It is worth noting that waxed Venetian Plaster will need topping up from time to time. The exact frequency will depend on the condition that the plaster is exposed to, but it can generally be judged by keeping an eye on the finish of the plaster. If it starts to lose its glossy sheen, it is probably time for another coat of wax.
An alternative to waxing comes in the form of lacquer, or glaze. This kind of sealant is different from wax in that it is a true coating in the sense that it does not soak into the plaster, as wax does, but sits on top of it, forming a barrier between the plaster and the outside world.
Acrylic is the most popular base for Venetian Plaster sealant. While a talented enough plasterer will be able to create a great-looking surface regardless, the glaze does tend to give a slightly less natural look to the plaster. On the other hand, it also offers a greater degree of protection, and you should not have to re-apply lacquer over time—indeed not anywhere near as often as you would with wax.
Glaze fills a middle ground between the 100% authentic look of waxed Venetian Plaster, and the look you would get from recreating the Venetian Plaster effect with paint. The fact that you have real Venetian Plaster underneath the glaze gives you that sense of depth that paint cannot replicate, while the protection of the glaze gives you the kind of durability you would expect from paint. Like wax, both matt and polished finishes can be achieved with a lacquer finish, though it is more crucial that you pick the right kind of lacquer, to begin with.
Olive soap is another option that has been around for a very long time. Thousands of years, in fact, if you count Moroccan Tadelakt, which is very similar to Venetian Plaster.
Olive soap reacts with the lime in the plaster, making it extraordinarily hydrophobic and dirt-resistant while maintaining the breathability of the material. This is great for bathrooms and other areas where the plaster may get wet. Olive soap can also be an ingredient in wax, giving you the best of both worlds.
Choosing the Best Sealant For Your Venetian Plaster
Choosing the best sealant for your Venetian Plaster project will likely depend on how many compromises you are willing to make. For example, the purest form of Venetian Plaster would also probably be the most expensive in terms of materials and would require the most continued upkeep with regular re-applying of wax.
If having the most authentic Venetian Plaster on your walls is not essential to you, you could opt for a lacquer finish. This is perhaps not quite as natural as a wax finish, but it is more durable and, depending on the desired look and feel, can be easier to apply. It’s worth noting that lacquer will also hinder some of Venetian Plaster’s more desirable attributes.
Lime is naturally resistant to mould and mildew, which makes it excellent for use in bathrooms and kitchens. However, if you coat your plaster in lacquer, the lime is not exposed and, thus, not in a position to resist anything. The mould and mildew could just form on the lacquer instead. It also removes the breathable nature of Venetian Plaster—something that helps prevent damp.
If money and future maintenance is no object, it is hard to argue against a good wax—especially an olive soap wax. However, Venetian Plaster is already more expensive than other forms of plaster, so it would be understandable if cost concerns played a significant role in your decisions regarding which sealant to use.