When it comes to Wi-Fi, most of the time our concerns are related to the signal not going far enough, but the opposite problem also exists.What if you don't want a Wi-Fi signal leaving a room? Or, alternatively, what if you don't want people within a room to receive any radio signals? The usual solution here would be to build a Faraday cage, which blocks radio signals from coming or going, but that's an expensive proposition.But, what if you could get the same effect by just giving a wall a new coat of paint? Years ago, some researchers in Tokyo showed us it was possible, but what happened to this idea? After all, we might need it now more than ever! We were promised a Faraday cage in a paint can Painting yourself into a Wi-Fi corner In 2009, as reported by ZDNet, researchers in Tokyo published a paper detailing the creation of what the media ended up calling "Wi-Fi blocking paint." That includes when one of the researchers spoke to the BBC, but the actual paper doesn't contain the word "paint" so that was just the popular media doing the usual thing where it oversimplifies a paper for the public.
Regardless, I remember at the time that the idea did intrigue people.One use that got people excited was that you could paint movie theaters with the stuff, and then no one's phone would get reception while inside.My colleague, Ismar Hrnjicevic, demonstrated how metal can block Wi-Fi when he tried to use foil to improve signal.
Needless to say, it did not work! Close While the Japanese researchers had a novel formulation, the idea was hardly new.Years earlier in 2004, EE Times reported that a Silicon Valley startup called Force Field Wireless was set to sell Wi-Fi blocking paint at $69 a gallon.That's roughly $120 in today's money.
In 2012, Ars Technica published an article on French researchers who had invented a wallpaper that blocked Wi-Fi, but let cellular and regular FM radio through.So, it was touted as a potential way to stop hackers.Without the inconvenience of stopping other wireless comms.
The most famous “Wi-Fi paint” wasn’t really for Wi-Fi It was just media puffery The thing is, the Japanese paper that was reported on by the likes of the BBC describes a material that doesn't actually block Wi-Fi at all.It's meant to absorb millimeter-wave radio from 112GHz to 182GHz.That would apply to potential future high-speed wireless systems, but not Wi-Fi.
Even today, Wi-Fi tops out at 6GHz.Even the experimental mmWave 5G technologies top out below 71GHz, so that's too low for this stuff.But to make things even more hilarious, the one thing that mmWave radio is bad at doing is penitrating solid walls.
Even 5GHz and 6GHz Wi-Fi have a hard time going through walls that just have standard paint on them.It's that pesky 2.4GHz Wi-Fi that gets everywhere.Wi-Fi-blocking paint quietly went on sale under another name It's just that only a certain crowd cares You might be surprised that you can actually buy Wi-Fi-blocking paint right now.
It is normally sold as RF, EMI, or EMF shielding paint rather than “Wi-Fi-blocking paint.” These coatings contain conductive carbon, graphite, metal, or graphene particles.Once dry, they form a layer that reflects or absorbs radio-frequency energy.It costs $69 for 34 fluid ounces, which is way more expensive than $120 a gallon! Does it work? Well, the user reviews for it don't have anything to do with blocking Wi-Fi in particular.
It's mainly people who think they have a sensitivity to electromagnetism, which is not a recognized medical condition.The paint seems to make them feel better, but that could, of course, just be the placebo effect.Either way, it doesn't seem that people are actually using this expensive paint to block Wi-Fi for any sort of security purposes, but mainly for a perceived health issue.
One that can't really be tested scientifically.YShield RF Shielding Paint Brand Safe and Sound Color Black This paint promises to block wireless signals from internet routers, cell phones, smart meteres, and more.It may be useful when optimizing a room for maximum Wi-Fi performance or isloating a room from external interference.
Finish Type Metallic Item Volume 1L $69 at Amazon Expand Collapse Painting one wall won’t put your house in airplane mode While it's certainly possible to have paint that can shield a room from radio waves, and seriously reduce or interfere with Wi-Fi, how practical is it? Just painting the wall between you and your neighbor won't do the trick.You basically need to paint the entire room for it to have any chance of working, and if you have windows, those need to be blocked somehow.Radio waves propagate evenly in all directions, so if there is an unshielded spot, it will leak out.
This is why a Faraday cage has to be closed and continuous.A Faraday Bag has to be zipped up to work.So you're looking at a of paint to cover every exposure point.
That's hundreds or thousands of dollars of paint, which is probably at least part of the reason cinemas aren't painted with this stuff.If your concern is Wi-Fi security, it's cheaper and more effective to simply learn how to secure your router instead.
Read More
