Drive for the mist-free windscreen: New coating could make scraping ice from the glass a thing of the past, say scientists Scientists in the U.S. have developed a coating to keep windscreens clear Mornings spent scraping frost from windscreen could be thing of the past Coating could also work for spectacles and camera lenses, it is claimed Winter mornings spent shivering and scraping the ice from your windscreen could soon go out of the window. Scientists have developed a coating for glass which keeps it clear - no matter what Mother Nature throws at it. Created by researchers from the Massachusetts Institute of Technology, it repels rain but absorbs moisture from the environment rather than allowing it to gather as condensation. Frost free: The team tested coatings by chilling samples to -20C the exposing them to room temperature conditions. The new coating (right) remained frost free, and outperformed current anti-frost coatings (left) and untreated glass (middle) The coating is a 'zwitter-wettable surface' which absorbs molecular moisture from the environment but repels rain. This means that, in effect, rain will bounce off the surface but dampness in the air will be absorbed rather than allowed to gather as condensation on the surface. Engineers Michael Rubner and Robert Cohen of the Massachusetts Institute of Technology said: "It resists both fogging and frosting which could have uses ranging from automobile windshields to camera lenses." Its application could also work for spectacles or any kind of glass that is susceptible to getting steamed up in certain conditions, they said. Currently the best water-repellent coatings are good in very wet conditions for maintaining good visibility through the windscreen in the driving rain. But they do not prevent the glass from getting misty because of the condensation that builds up in wet weather, the researchers said. However, the latest version developed is called a 'zwitter-wettable surface' which absorbs molecular moisture from the environment but repels rain. Zwitter, Rubner said, is a German word for hybrid, used in a number of chemistry terms to describe something that carries two opposite properties at once. Frosty start: Scientists in the U.S. say they have developed a coating for windscreens that will keep it clear no matter what the conditions In this case, it describes a surface that has the ability to behave as both hydrophobic (to water droplets) and hydrophilic (to gas-phase water molecules). The surface is made by a process called layer-by-layer deposition. In this case, alternating layers of two different polymers - poly (vinyl alcohol) and poly (acrylic acid) - are deposited on a glass surface. 'The magic of what we do is nanoscale processing,' Rubner explains: producing the layers so as to control their properties almost down to the level of individual molecules. This production process appears relatively easy and inexpensive to carry out on large scales. 'These are common polymers,' Rubner says. 'They're well-known and cheap, but brought together in a unique way.' To test the effectiveness of this material, and that of many other alternatives, the team devised a set of extreme tests. For example, they kept samples of the material at minus 20 degrees Celsius for an hour, then exposed them to a very humid environment. Development: Scraping frost from your car windscreen on cold mornings may become a thing of the past While untreated glass, or glass treated with conventional hydrophilic or hydrophobic coatings, quickly develops a layer of frost following such treatment, glass with the new treatment remains clear. However, it still appears to be hydrophobic in the presence of large water droplets. They believe it could be used in everything from the inside of car windshields, to the inside of supermarket refrigerator cases and double glazing. Joseph Schlenoff, a professor of polymer science at Florida State University who was not involved in this work, says, 'Everyone knows how inconvenient, or even dangerous, it is to have a cold window or lens fog up when water condenses on it. The MIT group has devised a practical and effective method of combatting the fogging problem using a new ultrathin polymer film. How the anti-fog coating works