Lesson 5. Materials for Wall Preparation

In the previous lesson, we examined two main characteristics of base quality — flatness and smoothness. Preparing raw walls for the application of decorative plaster involves improving precisely these two indicators. In this lesson, you will learn which construction materials are used to enhance the flatness and smoothness of the surface in order to create an optimal base for décor.

The first and most important criterion of surface quality is flatness. This indicator is corrected with plaster. There are many types and techniques of plaster application, but their main purpose remains unchanged: to correct the geometry of the surface. Plaster is applied in one or several layers, ranging from 5 mm to 60 mm thick (per layer). In most cases, a single layer of a few centimeters is sufficient. It is applied across the entire wall surface, completely covering all irregularities, depressions, and height differences, thereby forming a new flat plane. Such wall preparation, when done properly, is suitable for thick‑layer decorative materials that allow the creation of textured, voluminous décor options.

If the raw wall material is unsuitable for plaster application — due to its tendency to deform, crumble, or having excessively large irregularities — drywall is used to correct the wall’s geometry.

Thus, we have two main options for improving the flatness of raw walls: applying plaster compositions or installing drywall. Next, if required by the decorative material, comes the stage of improving smoothness. To achieve a smooth surface, putty is applied over plaster or drywall in one or several layers. Each layer can range from 0.2 mm to 5 mm thick. Unlike plaster, putty can hide small defects and forms a thinner, smoother, denser layer thanks to its fine‑grained structure.

The material from which the raw walls are made has its own characteristics and influences the choice of preparation method. For example, log or timber walls require a different approach than brick or concrete walls. Plaster requires a solid base that is not prone to significant deformation. For this reason, plaster works best with mineral bases, although it is sometimes applied to log or timber walls.

Even though log and timber walls can be plastered using reinforcing mesh or lath (a framework of thin slats), the risk of cracks or other problems over time remains quite high. Wood is subject to deformation due to temperature and humidity fluctuations, and it may also suffer from rot, mold, or insect damage. The long‑term durability and stability of leveling such walls with plaster cannot be predicted with certainty.

When it comes to mineral bases — such as stone, concrete, or brick walls — plaster is one of the most effective preparation methods. These materials have high strength and stability, making them excellent bases for plaster mixtures. Unlike wooden walls, they are not subject to significant deformation due to changes in temperature and humidity. Moreover, when plaster is applied correctly, the likelihood of cracks is minimized. Consequently, decorative coatings applied to a base that does not negatively affect the preservation of the décor will retain their aesthetic appeal for a long time.

Understanding the logic and sequence of using materials in surface preparation for decorative plaster is very important for the craftsman. Once this foundation is mastered, we can confidently move forward step by step, delving deeper into the subtleties and nuances of the process.