Substrate preparation before application
Evaluation and corrections of the support
Proper evaluation of the support before applying a coating is essential for the success of the entire system. It should be borne in mind that:
The costs of quality evaluation, repair and preparation of the support are multiple times lower than the costs of the subsequent complete restoration of the entire system.
Areas to pay particular attention to:
Moisture content of the substrate
Although the application of microcement is a wet process, the substrate's moisture is essential. To be more precise, the substrate moisture's uniformity is critical: when you overlay with a microcement, there could be spots where the coating dries more slowly because of the water beneath. This effect will lead to a spotty discolouration of the surface.
It is never good to rush the application if the local areas are still wet. The best system to measure moisture is the carbide test, however, for an indicative assessment, it is possible to use some electronic device. The anhydrite floor must be allowed to dry completely.
Compressive strength
Substrate strength is essential for the proper functioning of the coating. Insufficient support strength may adversely affect the mechanical resistance of the microcement layer (falling objects). It is necessary to note that the coating system has approx. 3mm and at this thickness significantly assumes the properties of the substrate. The recommended minimum compressive strengths of the substrate for concrete and anhydrite are 30 MPa.
Cracks in the substrate
All cracks and fissures must be repaired and prepared for subsequent surface treatment. You can use an Ercole coating to address minor stable cracks in the support. In the case of unstable cracks resulting from the movement of the structure, it is necessary to remove the cause of their formation – cut the cracks with an angle grinder ("V"-shaped cut), fill with Ercole, cover with an alkali-resistant fibreglass mesh and repair them. We also recommend stapling the surface using epoxy resin and steel clips.
Homogeneity of the substrate
The Microbond coating should always be applied to a homogenous and solid surface, and it can be used to overlay common construction materials such as concrete, plaster, plasterboard, tiles, flexible tile adhesive, OSB boards, wood, laminate, anhydrite, paving or metal. Generally, smooth plastics are not very suitable surfaces for application. Suppose Microbond is not applied directly to a sound substrate. In that case, it is always necessary that the layer on which the Microbond coating is applied is consistent with the substrate and well adhered to it.
Substrate flatness and levelness
The substrate for the coating should be as flat and smooth as possible. Unfortunately, microcement overlays are so low-thickness that they cannot substantially level the surface; in reverse, the coating usually copies its trend.
In general, the better the surface is prepared, the easier it will be to apply the coating, and the final result will look better. Therefore, it is often advantageous to level the support before application, for example, with a self-levelling layer.
Uniformity of the substrate
It is crucial to have uniformity of materials in the support. Different substrate absorbency, structure, and flatness may result in a different look and feel in each area. You can use Primer 4T to uniform the surface. Classic acrylic primers are used for uniform absorption. You should use Cerbero Base for priming if decoupling the problematic substrate is necessary..
Preparation of the concrete substrate
Concrete is one of the most common floor substrates. It is a substrate with properties close to the microcement Microbond overlay. If there are no evident defects on the floor and the support is flat, applying the coating directly to this material after priming is possible. Suppose there is a risk of rising moisture on the surface. It is advisable to apply EverCrete Pavishield, a concrete hardener and consolidating product that protects from rising damp, before proceeding with Microbond.
Preparation of plaster and flexible tile adhesive support
The other common substrates for applying the cementitious overlays are flexible tile adhesive with reinforcing mesh and plaster. In general, these substrates are characterized by a relatively high absorbency. Therefore, for better workability and application of the coating, it is advisable to prime these surfaces with an acrylic primer in 1-2 layers. If you apply the microcement to an un-primed surface, it will dry quickly due to the absorption, as mentioned above. This absorption will lead to a more demanding application and a possibly darker shade on the surface. The Ecobeton coatings, as mineral cement-based products, are susceptible to drying time in this sense – it is always essential that the area of the intended application of the coating has a homogenous substrate in terms of absorbency. Therefore, using the Primer 4T for a safe and reliable application is possible, ensuring quality support preparation and speeding up the microcement application time.
Preparation of the anhydrite surface
Another relatively common substrate on which we apply coatings is anhydrite. It is a material based on calcium sulphate, which must be insulated by systemic priming before applying cement-based coatings. Most major manufacturers of construction chemicals have these materials in their portfolio. We have been using Bonding Agent and Cerbero Base products for a long time.
Before applying the coating to the anhydrite substrate, the following should be observed:
- the substrate must be perfectly dry (0.3 %)
- anhydrite should be of the highest strength class C30
- prior to application, a heating test must be carried out to detect any defects
- systemic priming
- perfect removal of the top-formed slurry
Preparation of the tile substrate
The Microbond coating can also be applied over tiles to prevent their complete demolition. However, the basic prerequisite for this application is the adhesion of the tiles with the substrate. If there are tiles that sound hollow on the floor or wall, it is necessary to evaluate whether this application method is suitable. In the case of a small number of hollow-sounding tiles, it is possible to repair them. In the case of a more significant occurrence of hollow-sounding tiles, it is desirable to abandon this procedure and remove the tiling. There may be multiple procedures for the application itself. In the following paragraphs, we will describe the individual options.
Application with fiberglass mesh
- Cleaning and degreasing of the surface with an alcoholic solution
- Partial grinding of glaze (min. 50%)
- Thorough vacuuming and priming of the surface
- Application of the Ercole coating using a 3 mm comb with subsequent insertion of the fiberglass mesh
- Surface smoothing
- Continue as before on floor
Application without fiberglass mesh with re-cementing of joints
- Cleaning and degreasing of the surface with an alcoholic solution
- Application of the Microbond or Microbond Finitura coating into the joints (cementing)
- Partial grinding of the glaze and the entire surface (min. 50%)
- Thorough vacuuming and priming of the surface
- Application of Ercole coating all over, additional grinding
- Continue as before on floor
Application with adhesion promoter
- Cleaning and degreasing of the surface with an alcoholic solution
- Application of the Microbond or Microbond Finitura coating into the joints (cementing)
- Application of Primer 4T adhesion promoter to non-absorbent surfaces
- Application of Ercole coating all over, additional grinding
- Continue as before on floor
Preparation of the plasterboard substrate
If you apply the coating to the plasterboard, it is necessary to prime the surface well. Especially in the case of overlay containing natural cement, in the case of poor priming, there is a risk that more absorbent cemented places will show on the coating and cause uneven drying.
If you want to ensure that the application will go smoothly, it is recommended to first prime the surface with classic acrylic primer and then apply a Primer 4T layer after drying. After drying, you can start to apply the coating. During this procedure, the surface of the plasterboard will be 100% insulated, and the application will proceed without any problems.
Suppose you apply the coating to the plasterboard in the bathroom treated with a waterproof layer. No additional measures are necessary, and you can install the coating directly on the waterproof layer.
Preparation of wood, osb, mdf, hdf type, plywood substrates
When applying the coating to wooden surfaces, it is advisable to prime the surface with 1-2 layers of Ecobeton Primer 4T. You can find the photo tutorial of the application here:
How to obtain a cement texture on furniture
Preparation of the laminate support
No complex preparation is necessary if you want to apply the Microbond coating to the laminate flooring. It is recommended to roughen the surface by sanding and then cleaning it with an alcoholic solution.
The first layer applied to the laminate wood may not be perfect. There may be various imperfections. The function of this layer is to bridge between the laminate and the microcement surface. It is recommended to allow the base layer to dry sufficiently (ideally for 24 hours). The second layer is then applied classically.
Surface preparation on waterproof layer in the bathroom
No further preparation is required for application to the waterproofing layer. Apply the coating directly to the waterproof coating.
Preparation of metal support
It is sufficient to properly clean the surface with an alcoholic solution to overlay metals. If rust is present, remove it completely or use Rust Buster Gel to convert it to an inert substance; it would be better to investigate the reasons for the formation of the rust to avoid future issues with the overlay. You can improve adhesion with a light mechanical prep (sandpaper or diamond grinding). Do not sand the galvanized surfaces; otherwise, the metal will be exposed to rust.
Preparation of asphalt
The asphalt preparation before applying the coating requires a thorough cleaning of its surface with a pressure washer. In the case of application on new asphalt, it is necessary to allow the asphalt to cure for at least 14 days and then clean the surface with a pressure washer before application.
Preparation of plastic surface
Although plastic is not an ideal surface, a coating can be applied to the plastic surface after it has been properly roughened.
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