When testing a substrate made of fibre-reinforced cement boards (they are not asbestos cement boards) efflorescence was found on individual elements, residues of release agents as well as algae and lichens. What activities should be planned when applying coatings on this material?
Efflorescence, especially algae and lichens, occur only on surfaces subject to long-term intense moisture. It should be clarified, what is the cause of this dampness. If structural damage is found on the façade, they must be repaired before painting. The cladding boards must be completely dry when the coating is applied. Remove efflorescence after the boards have dried. Alkali-resistant coatings are recommended to be made in light colors or even as white, then the remnants of efflorescence can be easily painted over, and these places on bright surfaces will be less visible.
Because the cladding boards are already installed, and you only need to paint them on one side, pre-painting can be omitted. As a result of one-sided stress and moisture, the cladding boards may bulge and move.
Fungicides are used to remove algae and lichens. Dried and cleaned boards can be coated without major problems.
Release agent residues are difficult to remove completely. It is not possible to make a permanent coating on an uncleaned substrate. Plates, that cannot be cleaned, must be replaced. If the principal is not prepared for it, warranty against damage should be denied.
What materials are suitable for coatings applied to the external surfaces of fibre-reinforced cement boards?
Properly applied coatings on fibre-reinforced cement boards can be made with the following materials:
1) farby krzemianowe;
2) farby dyspersyjne krzemianowe;
3) farby dyspersyjne odporne na silnie żrące środki zasadowe;
4) farby silikonowe;
5) tynki z tworzyw sztucznych;
6) farby elewacyjne rozpuszczalnikowe;
7) lakiery dyspersyjne;
8) lakiery polimerowe rozpuszczalnikowe;
9) lakiery poliuretanowe.
Balcony railings made of new fibre-reinforced cement boards are to be painted with dispersion paints. Please list the steps during painting works in sequence
These steps are as follows:
1) zagruntowanie powierzchni środkami do tynków;
2) naniesienie powłoki z farby dyspersyjnej odpornej na wpływy atmosferyczne;
3) naniesienie powłoki wykończeniowej z farby odpornej na wpływy atmosferyczne.
The coating should be applied on all sides, also on the edges. If it is impossible, avoid the first coat of paint.