Natural selection: leaf of the Lotus plant with water droplets. (Photography by G J Bulte).
The Lotus Effect
The "self-cleansing" mechanism of the Lotus plant leaf has inspired a new generation of Nano cleaning and maintenance coating which binds with substrates at the molecular level. In this sponsored feature the Middle East distributor of the Sure Step brand explains the science behind these new coatings.
The relationship between modern Nano coatings and "self-cleaning" hydrophyte plant species is examined in this industry white paper by maintenance coating applicator and Middle East distributor of the Sure Step coating system, CSTC Qatar.
The Lotus Plant (Nelumbo nucifera) has developed a cleaning mechanism, often referred to as the "Lotus Effect", which is made possible by the formation of rough bumps (or epicuticular wax crystalloids) on the surface of its leaves. These reduce adhesion to water droplets; and their roughness creates spaces for water molecule spheres to form and attract dust or dirt particles, before before rolling off the leaf entirely with the help of wind-tilt and gravity.
Nano coatings are essentially nanoparticles dissolved in a carrier material (usually ethanol or an ethanol substitute and water) and work by spreading and forming a three-dimensional, network-like structure over a substrate when the carrier material the particles are dissolved in is volatised (evaporates). The result of this process is a finely-spaced, bumpy surface that mimics the hydrophobic qualities of the Lotus leaf.
Nano Coating Applications
Nano coatings are increasingly finding a variety of building maintenance and cleaning applications:
Concrete and Natural Stone
When applied to concrete and stone, nano coatings will impregnate the substrate and react chemically to create a non-sticky layer that is steam permeable and protects the target area from damage without altering its appearance or colour.
Typical applications for coatings include building façades made from concrete, marble, sandstone, brick and granite; concrete and stone flooring, and decorative and ornamental features and monuments.
Glass & Ceramic
Despite their smooth appearance, substrates made from glass and ceramic attract dirt, dust, bacterial and other waterborne and airborne contaminants which can degrade performance and appearance over time.
Nano coatings have been demonstrated to reduce, and even eliminate entirely, the need for complex cleaning and restoration processes. Typically, they will form a hard, durable, protective layer which covers microscopically-pitted glass or ceramic with a smooth, water repellent layer. In turn, this reduces adhesion to contaminants and facilitates cleaning since, in common with the Lotus leaf, all that is usually required is a good wash down.
Non-slip Hard Flooring Treatments
Nano coatings are a versatile innovation. Aside from imparting hydrophobic qualities, they typically increase static co-efficiency: a quality that is desirable in hard flooring (liability for slip-related accidents in the United Kingdom alone is estimated at £0.5 billion annually).
Floors made from concrete and hard minerals can be made safer by applying Nano coatings. Chemical treatment creates an invisible but sophisticated tread design that substantially increases slip resistance.
We have learnt that applying Nano coatings reduces maintenance, renovation and cleaning costs, and helps to protect building owners from slip-related liability claims.
From a facilities and asset management perspective, there is also clear evidence that Nano coatings increase the service life of treated substrates and maintain help to maintain asset values by maintaining aesthetic appearance.
Yet innovation is only meaningful when it helps to improve quality of life; an aim Nano coatings achieve by making buildings cleaner and safer places to visit, work and live in.
Mansoori G. A. and T. A. F. Soelaiman ‘Nanotechnology – An Introduction for the Standards Community’
Journal of ASTM International, June 2005, Vol. 2, No. 6
Karthick B. and R. Maheshwari ‘Lotus-Inspired Nanotechnology Applications’ Resonance, December 2008:
Ankit M. and P. Surana (2009). Bio – Mimicry of Lotus Leaf. Indian Institute of Technology, Kanpur Biological