Environmentally Compatible Facade: Biocide-free Paints And Plasters

Very few fans find green facades. By contrast, “green”, environmentally friendly methods of inhibiting algae growth on facades are becoming increasingly popular with building owners. The paint and plaster manufacturers reacted to this. They offer many products that fight algae without biocides. An overview.

Author: Susanne Sachsenmaier-Wahl

Algae and fungi are everywhere. Algae and fungi on the facade generally do not affect the structure of the building. Nevertheless, the greenish veil represents a visual impairment. Not infrequently, it leads to violent arguments between craftsmen and builders.

Today's builders are more environmentally conscious

For many decades, microorganisms on the building envelope were therefore tackled with biocides. But in recent years, more and more building owners have had reservations about the use of biocides in paints and plasters. The substances are permanently transported to the surface to develop their protective effect. She washes rain. Therefore, negative effects on the environment are feared. The call for biocide-free protective measures is getting louder.

"In recent years, the increase in environmentally-oriented private and public building owners has led to an increasing demand for facade systems that protect against algae and fungi without biocides and that comply with the principles of ecological building," confirms Mario Kranert, Capatect product management at Caparol when asked by the Malerblatt. Christian Poprawa, Director of Sales and Marketing at Saint-Gobain Weber shares this opinion: “The demand for algae protection without biocidal film preservation is growing steadily. More and more building owners and planners are actively requesting biocide-free paints and plasters. This reflects the growing sensitivity to environmental issues in broad sections of the population. The connection between biocidal active ingredients and the decline in biodiversity has been discussed for a long time. "Heiko Riggert,ETICS product manager at quick-mix, added: "Especially in the thermal insulation composite system, which contributes to environmental protection by saving energy, the desire for more sustainability is recognizable."

Create framework conditions for biocide-free colors

Politicians have also been trying for some time to curb the use of biocides on the facade. Christian Poprawa explains how: “The legislation reacted years ago and regulated the maximum amount of biocides in plasters and paints. The Federal Environment Agency expressly recommends the use of biocide-free facade products. Some federal states and municipalities have already adjusted their funding guidelines. They offer building owners funding for the use of biocide-free facade plasters and paints in new buildings or renovations, which creates additional incentives."

Dieter Stauder, Head of Plaster and Facade Systems Market Management at Knauf, also sees an increased demand for biocide-free products: “Knauf is growing disproportionately in this segment. To speak of a real boost or significant shifts in market share compared to the usual solutions is, however, exaggerated, "he puts in perspective, however, and adds, where he sees this as justified:" Habits and lack of information may be the reasons for this. Or the decision-makers focus on other aspects for their decision-making.”Georg Bischof, Product Management and Marketing at Relius confirms this assumption:“For customers, the protective effect against algae and fungus infestation is in the foreground.

Opportunity to reverse the trend?

The technology with which this protection is achieved plays a rather minor role here.”According to Dieter Stauder, the pressure to prefer biocide-free products to conventional ones is still too low. He considers the possibilities of the paint and plastering industry to initiate a turnaround here to a limited extent: "It should be noted critically that the breakthrough to the greatest possible substitution of biocidal products will only come when pressure" from outside "creates new framework conditions. Be it legal requirements, drastic further restrictions on the approved biocides, greater sensitivity in society or among decision-makers such as investors and architects. The intensive efforts in marketing specialist entrepreneurs and industry alone are not enough. But both are well advisedto convincingly address the topic now."

Alternative product formulations

And the industry is already doing this with a lot of commitment. Christian Poprawa is convinced that biocides for facade protection are outdated. "The future clearly belongs to biocide-free building materials," he says. His company had long since said goodbye to biocides: "With AquaBalance technology, our company has been pursuing a clear strategy for over ten years. At Saint-Gobain Weber, we do not rely on the use of biocides for algae protection, but on the further development of the hydrophilic principle. Over 15 million square meters of façade area have now been done with AquaBalance plasters, saving around 63 tons of biocides,”he explains proudly.

Numerous other paint and plaster manufacturers also offer - partly also for more than a decade - biocide-free products for the facade - albeit mostly in addition to the biocide-containing variants. Kirstin Willers, Dispersions Product Manager at Brillux, explains how her company deals with the topic of biocides: "First of all, every Brillux facade color is naturally biocide-free." The biocides only find their way into the color when the client has it demands. Because some builders still consider biocide additives to be the only way to prevent algae infestation on the facade.

Moisture and nutrient deprivation

The formulations of facade paints and plasters have been significantly optimized in recent years in order to achieve clean facades without the use of biocides. The innovations all have one goal: to deprive the microorganisms of their livelihood and thus prevent them from growing. The most important basis for microbial growth is an adequate supply of moisture on the facade surface. In addition, appropriate temperature conditions, necessary nutrients and, in the case of algae, a sufficient supply of light as an energy source are decisive for the risk of microbiological growth. While the light supply on the facade can hardly be contained, the other factors can be influenced. "The natural protection against algae and fungi is based on a coordinated product formulation,combined with physical building properties for optimal drying management of the facade system,”explains Capatect product manager Cornelia Hauschild.

effect

Most products that promise clean facades without the use of biocides therefore share a similar technology. Elke Kleen, product manager for facade paints at Alligator, sums up the principle of operation of the Kieselit product family as follows: “Silicel-based Kieselit products guarantee optimal physical properties. For example, they are not thermoplastic, have moderate hydrophobicity and are highly alkaline. Dirt is absorbed less strongly, the surface dries faster and more evenly. Together with the high level of alkalinity, this creates a surface that offers hardly any breeding ground for microorganisms.”

The rapid drying of the facade surface is the central element in the struggle for clean facades. "For permanent weather protection and long-term maintenance of clean facades without biocides, the moisture generated must be removed and removed as quickly as possible," says Heiko Riggert. Opinions differ, however, on how best to prevent moisture on the facade surface. Should facade surfaces be hydrophobic or hydrophilic, or should they have a bit of both in the end?

Hydrophobic or hydrophilic?

"The faster a facade surface dries, the less moisture-loving algae and fungi thrive on it," says Christian Poprawa. The AquaBalance technology from Saint-Gobain Weber therefore takes up and reinforces the hydrophilic principle of mineral plasters. “The moisture is drawn off the surface, stored in fine capillaries and then released again in a controlled manner as the temperature rises. In addition, the dew or rain drops adhering to the facade are spread. This increases their surface area and the facade dries faster (blotting paper effect)."

The Brillux Hybrid Protect technology used for Ultrasil HP 1901 is also based on a hydrophilic surface and thus the spreading of water drops. "On the one hand, the recipe with its physically optimized water balance ensures that condensation and rain do not remain on the surface of the paint, but are discharged into the subsurface and quickly released again from there in the form of water vapor", explains Kirstin Willers and adds: "At the same time prevented the hydrophilic paint surface that water drops can form here. So the facade dries much faster and shows no water film on the surface that could lead to the formation of algae.”A similar argument is used at Caparol:“The selected Capatect plaster and paint systems effectively inhibit a permanently high supply of moisture on the facade surface. The special surface structure of the nano-quartz grid (NQG) means that moisture is better distributed and evaporates extremely quickly,”explains Cornelia Hauschild.

A little bit of everyone

The Hydrocon system from qucik-mix also relies on the positive properties of mineral-bound building materials to be able to store moisture, but combines this with a slight hydrophobicity. “The partially hydrophobic Hydrocon silicate facade paint HC 425 takes on the function of a membrane and causes driving rain to drip off the facade and just a film of moisture, such as that found in B. as morning dew on the facade is passed on to the finishing coat due to the special structure and high water vapor permeability. Rainwater is immediately removed, but the finer condensate is quickly absorbed by the finishing coat and stored temporarily. With changing environmental conditions, the plaster dries quickly due to its purely mineral character,”explains Riggert, the principle of action.

Dirt runs off

The hybrid binder that Knauf uses in its MineralAktiv product family also combines hydrophilicity and hydrophobicity. Dieter Stauder describes its effect as follows: “In conjunction with the modern recipe, a hydrophilic surface results, which reduces the dominant amount of condensation on the surface to a fraction of the usual amount. Dry facade surfaces are not affected by algae and fungi. Driving rain, on the other hand, is quickly removed from the surface like a silicone resin paint.”

At Sto, nature has been used as a model for the optimization of facade colors and plasters. “The Lotusan facade paint was developed 20 years ago based on the Lotus plant. Dirt does not adhere to the water-repellent surface of its leaves, but is simply rinsed off with the next rain. We have transferred this principle to the facade color. On Lotusan, dirt simply rolls off with the rain,”says Frank Zippenfennig, product manager for facade coatings at Sto. The StoColor Dryonic technology developed later also follows a bionic principle. "The coatings of the StoColor-Dryonic family are based on the simultaneously hydrophilic and hydrophobic properties of an insect shell - the mist-drinking beetle - and carry rainwater,but even the smallest droplets such as dew and fog are immediately removed from the facade. The facades, which are always dry in this way, do not provide a suitable habitat for microorganisms such as algae or fungi - without any biocidal film protection agents.

Special pigments and alkalinity

The majority of paints and plasters that promise longer cleanliness without the use of biocides have a mineral binder base. This is not new, emphasizes Dieter Stauder: "Knauf has always relied on natural algae protection with its thick-layered mineral fine plasters." Knauf has also taken advantage of the alkalinity of the binder in the new MineralAktiv products: "The hybrid binder retains its alkalinity - even under the influence of the weather. The alkaline environment creates a surface that is hostile to algae and fungi, they cannot occupy the facade,”explains Dieter Stauder. Brillux also uses the properties of the inorganic components.“The second protection mechanism of Ultrasil HP 1901 results from the special recipe components of the over 95 percent inorganic constituents and a high pH value: all raw materials such as pigments, fillers, silicates and additives were selected so that they are virtually nonexistent for algae and fungi Provide nutrients. This reliably prevents vegetation on the facade surface for a long time,”says Kirstin Willers.

Pigments help

In addition to an alkaline environment, certain pigments also help to keep facade pollution at bay. "The Hydrocon facade paint HC 425 contains special color pigments that ensure a slight increase in temperature even in low sunshine and thus accelerate the drying of the facade", Heiko Riggert reveals to us. Knauf also relies on this effect: “We built an infrared absorber into the paint. This raises the surface temperature on the facade by 1-2 degrees even with bright colors. This also makes the facade even drier and therefore safer against algae and fungal attack,”Dieter Stauder explains the Knauf MineralAktiv technology.

The technology with which Relinova Bio Clean and Relinova Saniergrund from Relius are equipped is also based on the effect of a pigment. However, the focus is not on heating, but on photooxidation. “The innovative solution works through a special pigment and filler matrix. A photooxidative reaction takes place under the influence of daylight, in which the mineral film protection is permanently renewed. This means that the effect remains intact over the long term with the paint surface intact and is not reduced,”says Relius product manager Georg Bischof.

Durability and color

And what about the durability of the protection mechanisms described? How long does the protection last? Frank Zippenfennig sees the biocide-free Sto products at the same level as the conserved ones: “Depending on the location and constructive weather protection, comparable results can be achieved as with products with film protection agents. As a rule, facades are based on renovation cycles of 15 to 20 years.”Christian Poprawa believes that the AquaBalance technology from Saint-Gobain Weber is superior to the use of biocides:“The technology is based on a natural active principle. In contrast to surface plasters with biocidal film preservation, no active ingredients can be washed out. The protective effect is therefore not limited in time. The renovation intervals for facades are extended significantly. Mario Kranert shares this assessment: “Caparol's natural protection concept is based on a physical principle that protects the facade in a natural way and does not wear out. This means that renovation intervals can be extended significantly."

Tintability

With regard to tintability, there is little difference between biocide-free and film-conserved facade products. "The type and amount of binder essentially determines the choice of color," Frank Zippenfennig points out. “Basically, silicate products can only be tinted with inorganic pigments. Organic pigments are not compatible with the potassium water glass binder. This limits the color selection a little. Advantage: The color stability is increased. After all, inorganic pastes are more stable in color than organic ones,”adds Elke Kleen. But the selection is still huge. The current alligator color collection Impulse 6000 alone contains 399 shades that can only be achieved by using inorganic pigments,there are also thousands of colors from other collections.

According to Georg Bischof, Relinova Bio Clean can be tinted in around 11,000 different colors in the light to medium color range. Heiko Riggert does not give the color selection for Hydrocon HC 425 quite as extensive: “Due to the silicate binder base and the special IR pigmentation, very intense colors cannot be represented. But there are still more than 100 shades left for the agony of choice.”As with conventional colors, organically bound colors are ahead in terms of color: According to Frank Zippenfennig, Sto Color Dryonic S is available in any color. Cornelia Hauschild also presents the free selection for the Capatect products: "All color ideas can be fulfilled here as desired."

More photos:

Elke Kleen, product manager for facade paints at Alligator

“Kieselit products based on silicate guarantee optimal physical properties. A surface is created that offers hardly any breeding ground for microorganisms."

Christian Poprawa, Director of Sales and Marketing at Saint-Gobain Weber

The demand for algae protection without biocidal film preservation is growing steadily.

Dieter Stauder, Head of Plaster and Facade Systems Market Management at Knauf

Dry facade surfaces are

not affected by algae and fungi.

Kirstin Willers, Product Manager Dispersions at Brillux

First of all, every Brillux facade color is naturally biocide-free.

Frank Zippenfennig, product manager for facade coatings at Sto

With biocide-free products, comparable results can be achieved as with products with film protection agents.