Tips

Prepare the walls

Prepare the walls

It is essential to fill in holes and cracks and to prepare the wall surface well before applying coatings such as paint or wallpaper.

The right product

Among the wide range of filling and smoothing coatings, the best suited must be selected. You will have the choice between ready-to-use products, presented in the form of paste, and powder coatings which must be mixed in water, more economical.

Identify cracks

We must distinguish different types of cracks. The finest are due to defects in the plaster coating or the play of materials. They are stable and do not reappear once clogged. On the other hand, living cracks, due to the dimensional variations of the materials, which affect the entire thickness of the plaster and sometimes even the entire thickness of the wall, threaten to reappear and must receive special treatment, in this case a stabilizer.

Tools & materials

• Painter's knife
Coating knife
Triangular scraper
Trough to spoil
Sanding block
Stepladder -
Filling plaster paste (tube or jar) and powder
Fine plaster
Expansive foam
Interfacing strip

Powder or paste?

The coating, filling or smoothing, presented in powder form is more economical. It is best suited for large areas, large filling jobs and smoothing. Spoil it in a trough, respecting the proportions recommended by the manufacturer, and take care to mix well in order to obtain a homogeneous dough. Dough plasters have the advantage of avoiding preparation time and of presenting a perfect dosage, without risk of mixing error.

Other coatings

• The fatty coating is used to fill holes and cracks both inside and outside. It leaves a hard, waterproof and relatively difficult to sand surface. Indoors, it must be reserved for places exposed to humidity.
The lacquer coating is a particularly fine smoothing coating, which leaves a clean and flat surface, for a smooth finish like a mirror with a glycerophthalic lacquer. Prefer coatings to be lacquered in paste because the dosage of the product is of great importance for the success of the operation.

Interlining

To prevent living cracks on the walls or ceiling from reappearing after a few weeks or months, it is necessary to stabilize. Widen the crack with the triangular scraper before filling with a coating; then apply the calico strip on the plaster, tightening with the plastering knife. Then apply a new coat of plaster so as to drown the strip of tulle. Create a little extra thickness to compensate for shrinkage on drying. Let dry and sand. Know-how © La maison rustique - éditions Flammarion, 2005