Researchers create paint that blocks Wi-Fi signals - http://news.bbc.co.uk/2...
"The paint contains an aluminium-iron oxide which resonates at the same frequency as wi-fi - or other radio waves - meaning the airborne data is absorbed and blocked. By coating an entire room, signals can't get in and, crucially, can't get out. Developed at the University of Tokyo, the paint could cost as little as £10 per kilogram, researchers say." - Tom Stocky
I must have used that paint in my last house without knowing it! - Lou Paglia