Ready for Africa - Wacker Chemie AG

Ready for Africa

Silicone resin emulsion paints are the most effective and durable architectural coatings, with a track record in Europe of over 50 years. With support from WACKER, Crown Paints, a Kenyan company, recently launched the first formulations aimed at the African market.

High-Performance Coatings for High Durability: Silicone resin emulsion paints and plasters based on SILRES® BS unite the advantages of emulsion and silicate paints: they are both water-repellent and water-vapor permeable. As a result, hardly any moisture penetrates into the wall from the outside or inside, yet the facade can breathe by allowing water vapor to escape.

Every house is defined by its exterior. A spotless, fresh facade is attractive and inviting. But to keep its good looks over the years the house must defy the ravages of the elements – and that calls for efficient paints and renders. These not only give the front of the house an individual note, but also provide lasting protection against the elements – sun, wind and, in particular, rain. In countries with high rainfall, high atmospheric humidity or strong sunlight – like in sub-Saharan Africa – outer walls must be protected against water and the resulting damage. “SREPs are the highest quality and most effective coatings for exterior walls currently available on the market, but had been hardly used in Africa until now,” explains Sebastian Hock, Marketing Manager at WACKER in Munich.

That has now changed. Silicone resin emulsion paints are all set to give Africa's houses a face-lift and to provide all-round protection for exterior walls.

Extreme Weather

In late 2014, Kenya-based Crown Paints, with support from WACKER's experts, became the first paint maker to add the premium-quality paints to its range. “The weather in this East African country varies enormously: Its western part receives six times as much precipitation as Northern Europe,” says Anoop D’Souza, a sales manager for Middle East & Africa at WACKER in Dubai. “Almost everywhere else in this country, it is extremely dusty.” In the East, there is also a salty breeze from the Indian Ocean. Buildings must be protected against these natural enemies – particularly water. After all, “Defects that allow moisture to penetrate the surface are to be found on all exterior walls,” explains WACKER manager Sebastian Hock. Barely visible hairline cracks provide a route for moisture to seep into the building fabric, where it causes damage such as spalling and salt efflorescence. Permanently damp exterior walls are an ideal breeding ground for micro-organisms such as algae and fungi. They also make it easier for soot particles and acid rain to wreak havoc with the building’s skin.

Cape Town’s commercial center: African architects often work with more vibrant colors than their counterparts in Europe or North America.

“Exterior walls are made with all kinds of building materials, such as natural stone, concrete and bricks. Each of these mineral-based materials responds differently to weathering and environmental factors,” explains Christian Putz, a paint systems engineer at WACKER in Burghausen. “Yet, for all of them, silicone resin emulsion paints provide the most effective protection,” he stresses.

When it comes to the ingredients that are needed to make up the proper paint formulation, this WACKER expert knows his stuff. He used his knowledge to help the Kenyan paint maker develop the optimum recipe for the regional market. “The ingredients and the mixing ratios are crucial to the end result,” says Putz. However, all the recipes have one thing in common: they contain a silicone resin binder. “Silicone resin emulsion paints dry to form a microporous film that allows high water-vapor permeability while protecting the wall against liquid water,” explains Putz. In the process, the silicone-resin binder forms a network structure, and we therefore use the term “silicone resin network.” The backbone is a stable silicon-oxygen chain, while organic groups, like little umbrellas, are responsible for the water repellency – giving the paint its hydrophobic and weathering-resistant properties.

Ideal Properties

Breathable yet water-repellent – it is this combination which makes the silicone resin network so effective. Moisture collecting behind the coating can thereby easily escape to the outside. As a result, this high-quality moisture protection even works on slightly defective surfaces, e.g. with cracks. “And the hydrophobic layer provides an attractive visual effect, so-called beading,” says Hock. The water droplets roll off the treated surface easily and freely. As they do so, they wash away dirt and microorganisms – ensuring that the exterior walls and masonry retain their good looks for much longer.

At the same time, the walls are color fast. “Silicone resins even resist dilute alkalis and acid rain as well as the ultraviolet and infrared components of sunlight,” adds Putz. “All these properties are the reason why silicone resin emulsion paints are longer lasting than other coating systems,” he notes.

Cross-section through a facade painted with silicone resin emulsion paint: the silicone resin binder forms a three-dimensional network – the silicone-resin network. Stable silicon-oxygen bonds (blue) form the backbone on which organic groups act as umbrellas (yellow). They are responsible for the water-repellent effect, providing the coated facade with hydrophobic and weathering-resistant properties.

Efficient and Durable

They also outperform other paints in terms of the cost-benefit ratio. The savings here are important not only for individual property developers, but also at a macroeconomic level. In Europe, house painters, planners and property developers have been successfully using silicone resin emulsion paints for over 50 years because of their unique performance. They coat more than a million exterior walls all over Europe. “Many of these haven’t needed repainting in over 20 years,” says Hock. The longer intervals between renovations offset the slightly higher price of these exterior paints.

Silicone resin emulsion paints are now set to slash building maintenance costs in Kenya, while simultaneously defying the extreme weather. Rakesh Rao, managing director of Crown Paints, has no doubts: “This is another major milestone for us. With the support of WACKER, we have developed the best product for the local market.”

The WACKER experts also helped to train the 500 Crown Paints employees who work in customer support and sales. Word of their expertise and the good reputation enjoyed by silicone resin emulsion paints has spread far and wide. “We’re already working with other customers in South and East Africa on custom solutions for regional markets,” explains Hock.