The property of glass that makes smudges difficult toremove is the same one that causes it to fog easily — a fatal attraction togrease. Oils stick more strongly to glass than water, and when water ends up ona pair of ski goggles that haven’t recently been cleaned, it tends to bead upon the oil that’s stuck to the glasses. If glass were coated with something that made it attractwater more strongly than oil, however, then both of these annoying problemscould be solved, realized Jeffrey Youngblood, an associate professor ofmaterials engineering at Purdue. So Youngblood and postgraduate student John Howarter wentto work, eventually developing a coating made of two layers. The bottom layer,consisting of a water-loving solvent called polyethylene glycol, pulls water in.The top surface contains a Teflon-like molecule that islarge enough to prevent oil from passing through. The net result is that watercoats the surface, forming a smooth thin layer rather than beading up, and oilis repelled—no smudges, no fog.Most of the testing was done on glass surfaces, butYoungblood said preliminary studies show it should work on plastic lenses, too.“Anybody who’s gone [snow] skiing could realize thepotential importance of being able to do that,” said Kent Kirshenbaum, a chemistat New York University who was not involved in theresearch.The coating has another major plus, too—it isself-cleaning. “You add water, and the oil just comes right off,” Youngblood toldLiveScience. When water is added to the surface, it is pulled to the bottomlayer, literally moving underneath the oil and displacing it.