Here is the latest nanotechnology 'Made in Arcos', Navarro, in northern Spain. Tecnadis PRS EFFECT is a water-repellent for facades and historical monuments based on nanoparticles. It is being tested on the Cathedral of Santiago de Compostela to prevent the porous stone from absorbing water and humidity, and hence, to make it last longer. What makes this especially suitable for heritage conservation is the fact that it does not close the pores of the stone but instead, lets it breathe.Most protective coatings cover the stone completely by closing the pores, which often results in broken stones due to the humidity that is inside the stone and the changing weather conditions. Apart from allowing full breathability of the material, Tecnan's new coating does not change the brightness, tone or natural colour. It also helps keep surfaces cleaner for longer periods of time as it allows the raindrops to pull the dirt of the facade, similar to the Lotusan paint.
This new coating is a result of biomimicry and has been inspired by the lotus effect, based on the leaves of the lotus plant whose surface causes the water to slide over it, forming drops that don't penetrate but wash the dirt particles away. The nanoparticles that cover the stone are so small that they do not fill the pores but still repel the water.