A wall is not just a structural element of a building – it is also a surface that requires careful preparation before further finishing work. Painting, wallpapering, plastering – each of these stages can deliver an excellent visual effect or a complete failure, depending on how the surface has been prepared. The key to success lies in three concepts: primer, base and impregnation. Although to many laypeople they may sound similar, their functions are different, and the proper application of each requires an understanding of the material we are working with. This article not only explains the differences but also guides step by step through the process of wall preparation – from identifying the substrate to the correct application of the products.
What are primers, bases and impregnations? Basic differences
In the construction world, terms are often used that may initially seem synonymous. Primer, base and impregnation – although all serve to “prepare the wall” – have completely different roles, and their improper use can bring the opposite of the intended effect.
A building primer is a product designed to equalize the absorbency of the substrate and improve the adhesion of subsequent layers – paint, plaster, filler. There are deep-penetrating primers, which soak into porous surfaces, and surface primers, which form a thin layer on the outside.
A base, on the other hand, is a specific type of under-plaster primer, often used before the application of decorative or thin-layer plasters. Its task is to create a rough, uniform intermediate layer that increases adhesion of the plaster but also reduces the effect of uneven drying.
Impregnation, by contrast, acts as a protective shield – it does not so much prepare the wall as protect it. Depending on the composition, it may protect against moisture, fungi, mold or UV rays. It is most often applied on exterior walls, but increasingly also on decorative bricks or concrete walls in interiors.
Understanding these differences is the first step toward consciously planning finishing work.
Why is primer applied before painting walls?
Painting a wall is an activity that – it would seem – should not cause difficulties. Yet, if the priming stage is ignored, the result may be disappointing. Primer serves several key functions, the most important of which is to stabilize the absorbency of the substrate. Walls made of gypsum plaster or aerated concrete tend to excessively absorb paint, which leads to uneven coverage and discoloration. Primer acts as a regulator – limiting the absorption of paint and allowing it to spread evenly.
Equally important is the improvement of adhesion. Paint or plaster applied directly to an unprepared substrate is less likely to bond properly. The result may be cracks, peeling surfaces, or even entire patches of paint falling off.
It is also significant that a primed wall consumes less paint. Although purchasing primer is an additional expense, in the long run it provides savings – both in materials and time.
How to prepare a wall before priming and impregnating?
The application of primer is only one stage. The crucial moment comes earlier – preparing the wall, which determines whether the primer penetrates where it should and fulfills its function. First of all, all dirt must be removed – dust, grease, debris, remnants of old paint coatings. Otherwise, the product will not have the chance to penetrate the wall structure.
If the surface has defects, cracks or crumbling plaster fragments, these must be filled and smoothed. It is not worth priming “carelessly,” hoping the product will cover all imperfections – its task is not to mask but to stabilize. Only after sanding and dusting off the surface can one proceed further.
A very common question is whether the walls should be washed before priming. The answer is: yes, if they are dusty, greasy or freshly renovated. A clean, dry and uniform surface is a necessary condition for the primer to work properly.
How to apply primer? Step-by-step instructions
To achieve the desired result, primer should be applied following a few simple rules. Most often a roller is used – especially for larger surfaces – or a brush for corners and hard-to-reach areas. The product itself should be applied evenly, in a thin layer, without excessively saturating the wall. If the primer begins to run down, it means it has been applied too heavily.
On very absorbent surfaces – such as raw plaster or aerated concrete – it may be necessary to apply a second coat. However, it is important that the first one is completely dry before the next is applied. Manufacturers usually recommend waiting between 4 and 24 hours, depending on conditions: temperature, humidity and substrate type.
Diluting the primer is another point of concern. Some products require dilution with water in specific proportions, while others are ready to use. Here it is essential to strictly follow the manufacturer’s recommendations – primer that is too diluted will not fulfill its role, while too thick may create a shiny, glazed layer on which the paint will not hold.
How to apply impregnations on internal and external walls?
Although priming is often considered the key stage in wall preparation, one must not forget about impregnation – especially for surfaces exposed to moisture, dirt or microorganisms. Impregnation, unlike primer, does not serve to improve adhesion but aims to protect. Depending on the type, it may guard against water, grease, UV radiation, as well as fungi or algae.
Indoors, impregnations are most often applied on decorative bricks, textured plasters and “loft” style concrete walls. Their role is to preserve the raw look of the material while making it easier to clean the surface and prevent discoloration. Vapor-permeable impregnations are popular in this context, as they do not completely block the pores of the material but form a thin protective layer on its surface.
Outdoors the importance of impregnation grows significantly. Facade walls exposed to changing weather conditions require special protection. Rain, snow, frost, strong sunlight – all these factors can accelerate the degradation of material. Silicone, siloxane or acrylic impregnations form a durable hydrophobic barrier that prevents water from penetrating the wall structure. This not only protects against streaks and efflorescence but also limits the growth of microorganisms.
Application of impregnation requires attention. The product should be applied to a completely dry and cleaned surface. Sometimes double application is recommended, using the “wet on wet” method – that is, before the first coat has completely dried. It is important to avoid excess – too thick a layer may cause streaks and gloss, especially on porous materials such as brick or concrete.
Not every impregnation is suitable for every type of surface. For absorbent substrates – such as cement-lime plasters – deep-penetrating products are advisable. For gypsum walls or painted surfaces, surface impregnations may be sufficient. There are also specialized impregnations: anti-graffiti, anti-dust or antibacterial – the choice depends on the intended use of the space.
Contrary to popular opinion, impregnation should not be treated as a substitute for primer. They are two completely different products whose functions complement each other but do not overlap. In some cases – e.g. with decorative brick walls – one first applies a deep-penetrating primer and only after it has dried, a hydrophobic impregnation.
Typical mistakes when priming
Although applying primer seems trivial, practice shows that this stage is often performed incorrectly. The most common mistake is applying too much product. Instead of a thin, even layer, a glassy coating forms, which hinders adhesion of subsequent materials.
Another serious mistake is priming a damp substrate. Even if the wall appears dry, after previous washing it may still contain internal moisture. In such a situation the primer does not penetrate the structure but creates an irregular layer on the surface.
Equally important is improper dilution – especially in the case of concentrates. Too much water reduces the effectiveness of the product, while too little may cause too dense a consistency and difficulties in application.
Mistakes when using impregnations
For impregnations, the most common problem is a mismatch between the product type and the substrate. For example, applying silicone impregnation to a smooth, non-absorbent surface has no effect – the product cannot penetrate the structure and simply runs off.
Another frequent oversight is skipping the test stage. It is always worth testing impregnation on a section of wall – especially in the case of natural materials such as brick or concrete, which may change color after application.
It must not be forgotten that impregnation, like primer, requires appropriate weather conditions. Outdoor work should be carried out at temperatures above 5°C and without rainfall for at least 24 hours.
Choosing the right product for the wall type
Every wall has its own specifics – and therefore also different requirements when it comes to priming and impregnating products. There is no universal product that works in every situation.
Walls made of aerated concrete are highly absorbent – here deep-penetrating primers that reach inside the structure and bind loose particles work best. Gypsum skim coat walls, on the other hand, require surface primers that even out absorbency but do not penetrate too deeply, which could weaken the delicate substrate.
For decorative brick walls, vapor-permeable impregnations are recommended, which protect the material from moisture but do not block its natural breathability. Acrylic and siloxane impregnations are the safest choices in this context.
Order of application and product compatibility
Choosing the right products is one thing – equally important is their proper sequence and mutual compatibility. Incorrectly combining primers, bases and impregnations may disrupt the entire application process and reduce the durability of the final effect. That is why it is so important to use products thoughtfully and in accordance with the execution technology.
For raw, porous walls – such as cement-lime plasters – the process should begin with priming. This ensures the stabilization of absorbency and prepares the structure for subsequent layers. If decorative plasters are to be applied, the next step is the base – forming an intermediate layer that allows the mass to spread evenly and increases adhesion. Impregnation is applied at the very end – only after the decorative layer has dried completely. Its task is to protect the finish against dirt, moisture and UV radiation.
It is also important that all products used come from one product system. This way we can be sure that their chemical composition is compatible and physical parameters do not conflict. Products with different bases – e.g. acrylic and silicone – may not cooperate properly, resulting in delamination or loss of protective properties.
In our company we make every effort to ensure that each primer, base or impregnation we offer is part of a comprehensive system that can be safely used at different stages of work. We provide not only products but also knowledge – offering technical support and precise application instructions tailored to the specific material and working conditions.
Durability starts with the foundation
A well-prepared wall is the foundation of durable, aesthetic and trouble-free finishing. Regardless of whether you plan painting, plastering or decorative textures – the process should always begin with the conscious selection of primers, bases and impregnations. They determine not only adhesion and aesthetics but also resistance to external conditions, dirt and the passage of time.
As a manufacturer of solutions for professionals, we know how important trust in quality and repeatable results is. That is why we create systems that respond to real market needs – based on experience, research and execution practice. Our priming and impregnating products are the result of years of development – natural in composition, effective in action, easy to apply.
If you are looking for solutions that truly work – choose systems created with durability, functionality and aesthetics in mind. We invite you to contact us and learn about our full offer. We will help you choose the right product, suggest the optimal technology and guide you through the entire process – from a raw wall to the final finish.
Because every durable result begins with a well-prepared substrate. With us, you will do it professionally – from start to finish.