Repainting with Mineral Paints

Repainting is a natural activity in the lifecycle of a building structure. Over the years the default paint used on majority of the structures are polymer-based paints, mainly of the acrylic variety.

Painting over a previously painted building with mineral paints can be challenging and ideally the entire old paint is stripped off to expose the original masonry surface. This allows the silicate based mineral paint to chemically interlock with the surface, providing optimum performance. This process however is cumbersome and very expensive.

With Zydex Silicate Mineral Paints, this process can be avoided and the paints can be used to overcoat existing acrylic coatings provided they are in good, adherent condition.

Any loose flaking paint and debris including biological growths such as algae and fungus must be thoroughly removed using biocidal agents and high-pressure jet washing. Painting on weakly adhered paint or crumbling surfaces will result in immediate debonding of the Silicate Paint being applied due to the high setting tension of these paints. In this case, further consolidation and priming of such weak areas is required before reapplying the paint. Any cracks on the surface should be widened before repair.

At this stage, the entire surface should be saturated with Zycosil+ solution (Zycosil+ / Water / Zycoprime+ in 1:20:2 ratio), a penetrative silane-based water repellent primer that not only penetrates into the small hairline and micro cracks that have developed over a period of time due to weathering, but also in the large visible cracks that have been widened. This can be done using a roller or a low pressure airless spray.

The penetrative silane-based water repellent has two functions. First, it has the ability to penetrate inside the cracks and render the inside surfaces waterproof. This is important because even if water somehow enters these cracks, it will be held inside the crack like a cup that holds water. It will not be able to seep into the structure through the side walls of the cracks. Secondly, it acts as an adhesion promoter that acts as a compatibilizer for the oncoming mineral paint onto the existing acrylic-based paint. It is very important that the Zycosil+ solution is applied till saturation (until the surface can absorb no more) and not just superficially. It is also important that the surface is allowed to dry thoroughly before proceeding as the drying process is important for effective treatment.

After the Zycosil+ water repellent primer solution has been applied, including saturating the inside of the visible cracks, the cracks can now be filled. They should be filled using mineral based crack fillers only. A workable paste of Grey or White Cement with Elastobar is the preferred material. Acrylic and Silicone based crack fillers should be avoided as these are extremely soft materials and silicate mineral paints being brittle tend to crack when applied on them.

Once the surface has been cleaned, primed and repaired according to the above procedures and guidelines, It is now ready to receive two coats of Zydex Silicate Mineral Paints for a long lasting protection of your newly repainted project!