Using Aluminum Oxide Paint To Secure Wi-Fi 271
eldavojohn writes "The BBC reports on people using aluminum oxide in their paint to block Wi-Fi signals from leaving their home or business. Aluminum oxide resonates at the same frequency as Wi-Fi signals and other radio waves, blocking data from going outside a building. It's not a flawless solution, as it may also block AM/FM signals. You or your neighbors may be unwittingly using this already, as most pre-finished wood flooring uses aluminum oxide as a protective coating."
Cellphone reception? (Score:4, Interesting)
Wouldn't keeping radio signals in also have the unfortunately side effect of keeping radio signals out? While having a neighborhood coffee shop offer free wifi to paying customers while being an of oasis of cellphone-free peace & quiet would be sweet, having no cellphone reception at home because one desperately wants to prevent neighbors from stealing one's wifi seems very inconvenient (especially when setting up even the most basic built-in wireless router security would successfully do the trick in 99.9% of cases).
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Wifi works at around 2.4 Ghz, GSM frequencies [wikipedia.org] are between 380 Mhz and 2 Ghz, with the most frequently used frequencies being GSM900 (890-960 Mhz) and GSM1800 (1710-1880 Mhz).
From the article:
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.
I assume this means the aluminium-iron oxide resonates at around 2400 Mhz, which shouldn't interfere with normal cell phones.
Re:Cellphone reception? (Score:5, Informative)
Try reading more carefully:
FTFA:
From the sounds of it, just about anything below 100 GHz gets blocked. That means cellphones, too.
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"Our current mobile phones work at much lower frequencies, around 1.5 gigahertz. But, our material can also absorb frequencies that low, so you could block phone signals from outside and stop people's phones ringing during the movie," he said.
They said "can" and "could", not "does" and "will". There might be a switch. Or even different versions, which I guess makes a little more sense.
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The paint could also provide some much-needed relief during nights out at the cinema.
Our largest local movie theater installed an electronic cellphone signal blocker some years ago. It worked very well and almost put them out of business.
You see people on call (like Sysadmins, Doctors etc...) and people who feel a need to be reached on short notice for personal reasons (parents of small children), no longer saw that theater as an option for dates. This might not be a problem in some places but because of the lower pay scales (and hence higher relative cost of movie tickets) here, those
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This is why having a posted "keep cellphones off or vibrate only" rule is much better than active or even passive signal blocking. Granted, there will still be a few assholes that do not follow this, but thats where you exercise your right to kick them out.
IAAFLMTE (I am a former local movie theater employee).
Also, people who try to bring small children into a Rated R feature need to die in a fire. Its not because we care how about shitty of a parent you are, other patrons do not want a screaming kid while
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Someone brought their kid to the opening weekend showing of 300. I'll let you guess which scene the mom ended up taking her child out at (hint: it was early on)
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When I mentioned parents of small kids, I'm talking about people who leave the kids at home and can't bare to have the babysitter unable to call in an emergency (Where do I put use diapers again?)
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Was this in the USA? The reason is that doing this, while so very nice to prevent the idiots who don't know how to put their phones on vibrate from bothering everyone else, is also highly illegal.
The reason is that it can interfere with emergency calls even outside the building. The FCC can impose fines on the order of thousands of dollars per day th
Re:Cellphone reception? (Score:4, Informative)
The reason is that it can interfere with emergency calls even outside the building.
Actually the primary reason that jammers are illegal is that they are unlicensed. All unlicensed transmitters are illegal in the USA.
There is also a section of the FCC rules that prohibits interference in most cases, and absolutely prohibits willful interference.
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They were compelled to turn it off ontil they could contain the signal. within the walls. This fancy paint might actualy help them. I realy don't know how the open "play area" between the outer walls and the cell block will affect this. (Tha
Re:Cellphone reception? (Score:4, Informative)
Was this in the USA? The reason is that doing this, while so very nice to prevent the idiots who don't know how to put their phones on vibrate from bothering everyone else, is also highly illegal.
I think you are confusing active vs. passive blocking. Active blocking is illegal as it involves transmitting signals on the same frequencies as are used by cellphones, and this is regulated spectrum. Passive blocking, by using special paints or metal screens is perfectly legal.
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You see people on call (like Sysadmins, Doctors etc...) and people who feel a need to be reached on short notice for personal reasons (parents of small children), no longer saw that theater as an option for dates. This might not be a problem in some places but because of the lower pay scales (and hence higher relative cost of movie tickets) here, those affected were a major proportion of the theater's customer base.
Remember before cell phones? You could watch a whole movie in the theater without interruption? Your 3 year old was with the teenage babysitter, and if they both died or your house burned down, you wouldn't know until you got back home. Sysadmins didn't go to the movies because they would have gotten their asses kicked, and doctors were so fucking rich that they just bought the new releases and watched them at home when they were on call.
Yet somehow everything worked out just fine. If there was an eme
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They said it, but I have to wonder. Resonant generally means you have a dimension of order a wavelength. The paint particles are much smaller than the wavelength, so it sounds to me as if they are simply building a Faraday Cage, but with metallic paint, not aluminum foil or metal sheeting.
Note, if you are going to do this, you need to avoid holes the size of a wavelength / 4 or bigger - a few cm for WiFi (12 cm waves). If you like windows you should also put a fine wire mesh on them.
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And that's called a mosquito screen -- just make sure not to get one in plastic.
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You can get them in aluminum or fiberglass. Plastic is not standard.
Re:Cellphone reception? (Score:4, Informative)
Water molecules are famously resonant at 2.45 GHz, that's where microwave ovens operate,
No, they're not. That's a myth [vias.org]. There's no water resonance at or near 2.45 GHz. Water absorbs at pretty much any microwave frequency, with stronger absorption the higher the frequency.
If anything, you'd want to tune a microwave oven away from strong water resonances, because you want the radiation to penetrate (so as to heat the object evenly) and not be shallowly absorbed, which would result in uneven heating. (Note that a microwave oven is a cavity, so you don't need to absorb energy in a single pass-- it will resonate around until it does get absorbed.).
Re:Cellphone reception? (Score:5, Insightful)
Helpful hint for posters: if you don't know a damned thing about physics, don't answer questions as if you do.
Helpful hint for moderators: if you don't know a damned thing about physics, don't mod up posts full of word-salad wharrgarbl like "intra-molecular impedance."
http://www.howeverythingworks.org/prints.php?topic=microwave_ovens&page=4 [howeverythingworks.org]
Re:Cellphone reception? (Score:4, Interesting)
I stand corrected on the water resonance part.
The impedance part, well, perhaps Mr. Pink Corner needs to understand more where resistance comes from. The reason that microwave ovens work at all is that there is a resistive (ie dissipative, lossy, real, call it what you will) component to the impedance of water at those frequencies, dissipating EM energy into heat. Here's a quote from the nicely informative link Mr. Pink Corner provided:
Rather than interacting with the water molecules via a resonance, the microwaves in an oven heat the water by twisting its molecules rapidly back and forth so that they rub against one another. The molecules are heated by the molecular equivalent of sliding or dynamic friction. The choice of 2.45 gigahertz gives the water molecules about the right amount of time to twist in each direction. The precise frequency isn't important, but microwave ovens are required to operate at exactly 2.45 gigahertz so that they don't interfere with communication systems using nearby frequencies.
And here's another clue about physics, Mr. Pink Corner, when you have a complex impedance, like an RC circuit in a lumped model system, the speed of light through those components is determined by the RC time constant. The speed of light is slowed by the reactive portion of the impedance. In that system. Otherwise the movement of the current would not be impeded and the full voltage would appear at the far side of the C element instantaneously. But it does not: the speed of propagation is slowed, as reflected in the time constant. This becomes especially evident when you look at transmission lines and the impedance of the line determines the propagation speed (as well as the line loss due to heating of the real component of the impedance). Same thing in water, except, as I've been corrected, there is no resonance at 2.45 GHz.
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Re:Cellphone reception? (Score:4, Informative)
A conductive metal has free electrons which will block and reflect any waves below its plasma frequency. However, an ionic solid does not have free electrons - instead, it has just a few resonant other mechanisms with limited range so it will block a more specific part of the electromagnetic spectrum than a metal would. The frequency of wifi signals happens to be in the range of one of these mechanisms for the paint used.
Extra protection? (Score:5, Funny)
I'm already using aluminum foil lining in many of my hats and clothes to protect me from the government transmissions. However, I hadn't heard that Al2O3 was any better than straight aluminum foil.
It seems suspicious that this story would be posted immediately after I began considering papering my walls with foil.
Re:Extra protection? (Score:4, Interesting)
Give me a break. Next think he'll be trying to create is an Aluminum oxide / silver dip - keep away nasty radio waves and germs, all in one toxic package.
I think this guy is mostly looking for some investors.
Re:Extra protection? (Score:5, Insightful)
If I were a science teacher, I think I would have a weekly contest "What's wrong with this?". I'd give all the kids a website, newspaper article, creationist newsletter (probably lose my job over that one but oh well), etc... and have them come up with a list of all the reasons that it is nonsense. Start with easy stuff (like the difference between EM and Ionizing radiation) and move to more challanging things later (like what a valid sample size is). We need to expose kids to the idea that not everything they read is gospel, to think critically about what they read and see and actually apply their education.
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There's an idea for a startup - a company that creates additional homework for parents to give their children to make up for deficiencies in what their school teaches them.
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Maybe you could have like a 3rd party wiki addon for browsers that would allow you to add comments to pages, independent of the page itself. You could then browse other peoples comments as well.
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No major school system would ever allow this. If you teach them not to believe everything you read, the next step is they don't believe everything they are told. If they don't believe everything they are told, they don't assume their teachers and administrators are correct, and should automatically be listened to and obeyed. As the average modern American school has nothing to do with educating, and everything to do with babysitting, it would be very dangerous to the comfortable low expectations their st
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"I wish I had a cross made of kryptonite. Because then I could kill Dracula and Supperman."
-Jack Handy
Re:Extra protection? (Score:4, Funny)
No, not Supperman! He brings me my dinner!
Re:Extra protection? (Score:4, Funny)
I still cherish my pristine copy of Supperman #103, in which he manages to incapacitate the entire Third Reich by making them fall asleep after a huge turkey dinner.
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Ah yes, the elusive Supperman. I was very unhappy when Marvel finally decided to have him killed off by his arch-nemesis Bulimiax.
Now that was brutal ending for a superhero - he was literally chewed up and spit back out.
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Now that was brutal ending for a superhero - he was literally chewed up and spit back out.
But you have to admit it was a fitting end to the story arc that began when Supperman refused to save Bulimiax's adopted daughter, Anna Rexia, after she overused her power trying to starve a whole middle school. Dying, she promised she'd renounce her evil ways if he only gave her a bite of supper! Sure he may have had a point when he said she was lying and would never truly change, but finishing her off with "And you
Re:Extra protection? (Score:5, Funny)
Finally!! (Score:3, Funny)
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You need to make your hat out of sandpaper, the dark colored kind that is aluminum oxide. I'd recommend a fine grit unless you want the mellow exfoliating effect of 80 grit on your cranium.
Sheldon
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Paint your bald spot?
"By coating an entire room..." (Score:3, Funny)
Wouldn't you have to paint over the windows?
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You could use a fine metal mesh instead of paint for the windows.
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Aluminum siding!
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Even with gaps in the coverage, blocking most of the radio waves should be enough to massively diminish the reception outside the room. Given the already limited range of most wifi transmitters, a few gaps in the paint for windows shouldn't be enough to allow any practical use of the wifi signal from outside.
Now, if you're putting the paint up for security reasons the windows might constitute a real risk, but trying to restrict the range of your wifi transmissions is probably not the best approach to secur
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Obvious answer: Transparent aluminum. Its a lot stronger than glass, so you have less to worry about with storms.
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Actually, no. Transparent aluminium [wikipedia.org] is different, but given the amount of power it would take to maintain it in that state, hiring a dedicated team of ninjas to kill anyone using a wireless device would be cheaper.
Hey, it's good enough for the office... (Score:5, Funny)
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What you need to be really careful about is the cops in helicopters doing thermal imaging of roofs. They do this to find people running cannabis farms. If you are releasing a lot more heat than normal, then expect a dawn raid. Also, if they don't see any heat being released, expect a dawn raid because they will think you are trying to shield it.
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So that's what Tribett was up to!
http://www.flickr.com/photos/43492742@N00/352574903/ [flickr.com]
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Thanks for the tip, Buddy Ebsen [wikipedia.org].
Note: AlFeO *not* Al2O3 (Score:5, Informative)
Note, the material concerned is Aluminium IRON oxide. Big difference. Aluminium oxide is a good dielectric and would be bugger all use for RF shielding. Oh and the article is a wierd too: it talks about 100GHz shielding where WiFi bands are ~ 2.5GHz.
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I thought the same, but then I concluded that the wifi will be REALLY secure after exposure to that. And a bit of magnesium.
Does not resonate with me (Score:5, Insightful)
Dunno where they got the crap about "resonates".
The paint might act as an electrostatic shield, or as a lossy dielectric, both effects that will attenuate RF signals.
But resonate, no.
Re:Does not resonate with me (Score:5, Interesting)
with that being said, I highly doubt that simply painting your walls will keep RF signals at bay... Even when the grounding wire was simply loose on the door to the faraday cage, RF signals would leak in...
Re:Does not resonate with me (Score:5, Funny)
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Plug your filing cabinet in to your router?
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I take it you were using fiber optic cables into the Faraday Cage, so that you weren't adding electrical noise inside?
Otherwise it sounds like you're trying to put a device for protecting optical transmitting equipment from return losses on an ethernet cable.
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I am not an expert, but it seems to me that they would need careful attention to details such as those, to adequately block the signals. For example,
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There's only 1 way to complete protect a wireless network: Turn it off.
Everything else is just a layer to help protect it, paint addatives included.
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Make the windows out of Aluminium Oxide as well? Al2O3 is transparent.
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Conversely my brother in law works at a wireless lab where they have a copper clad cage, and when he closed the door my cellphone lost its network signal within a few seconds.
Strangely enough the government transmissions didn't stop infiltrating my brain :(.
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I'm still a bit skeptical as I've worked in EMI hardened facilities where we have solid wires leaving the structure to outside antennas and it's really not possible t
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Ionic materials can be polarized to interact with electromagnetic waves to block signal transmission. They have a number of absorptive mechanisms. The highest frequency absorption mechanism is where electrons around the nucleus resonate, roughly at 10^17 Hz. Then there's atomic vibrations where the nuclei themselves vibrate (10^14 Hz I think). Not sure what they are for the material used in particular though, but ionic materials can resonate. It doesn't seem that they're in the range used for this applicati
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This article is full of nonsense, it's not even worth the read. For example...
Movie pictures are beamed on the screen by the projector at the back of the cinema. But in the future, you could use a data link that works with millimetre waves.
What. The. Fuck. is that supposed to mean?
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Everyone will still go to the movie theater, but they'll watch the film on their iPhones. They will be confused when the "turn off your annoying cellphones (psst: you can buy annoying cell phones from AT&T)" message comes on, though.
Why not share wi-fi? (Score:5, Interesting)
We do know the world would be a better place if everyone shared their wi-fi securely using
a technology like FON, don't we. (No I'm not associated with the company. Just recognize a
great concept when I see one.)
I'm seriously tired of how, particularly in the US, sharing wi-fi gets implanted in peoples'
brains as a criminal, borderline terrorist activity, with terms such as
"theft of tele-communication resources" and similar Orwellian mindf**k terms.
Re:Why not share wi-fi? (Score:5, Funny)
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FON creates two different networks, one for sharing and one for private use, and AFAIK you can limit the bandwidth and throughput used by the public one.
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Correct. And you can decide if you want to share free of get a kickback. If you share for free you are also entitled to access all other FON nodes in the world, if you share for a revenue share you have to pay. Pretty fair model IMHO.
However, I'm unhappy with a node on my personal network where someone can change code on the fly, which is why I took it offline a while back.
Is it safe ? (Score:2, Interesting)
We all know about the hazards of lead based paints, so is this safe ? I'm assuming the plastic lining in aluminum cans is there for a reason. Perhaps adding panelling containing a solid aluminum oxide mesh of some sort would be better.
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We all know about the hazards of lead based paints, so is this safe ? I'm assuming the plastic lining in aluminum cans is there for a reason. Perhaps adding panelling containing a solid aluminum oxide mesh of some sort would be better.
An easy solution would be to stop eating paint.
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An easy solution would be to stop eating paint.
Yeah, but apart from kids eating paint chips when the house is demolished after a couple of decades the paint might get powdered into dust and be breathed in by the construction workers or just when someone sands it down or something. (I know: don't inhale, right ?)
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Easy until you need to sand the painted object to apply a new layer of paint.
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I checked my deo, but no aluminum so I googled around and apparently it's an ingredient in antiperspirant which is in some deodorants (mine's the plain kind). Interestingly this turned up some debate on the safety of aluminum use :
"A small study in 17 women with breast cancer was quite widely reported in the news in 2007. It found higher levels of aluminium in the part of the breast nearest the skin, and the authors speculated that aluminium in deodorants might cause breast cancer. But the design of this s
What is so hard about using WPA2? (Score:5, Insightful)
You select WPA2-PSK in your router's config, press "generate key", make a note of the generated key, connect your laptop to the encrypted WLAN, enter the key, done. No beacon disabling, radio frequency shielding, MAC filtering, DHCP disabling or other nonsense necessary. It's like people are trying to test every option but the right one.
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The guy who can break your encryption can easily get past your mac filter pretty easily. The mac filter is there for people who cant or wont use encryption. So its kinda like locking your car but putting a note on the steering wheel asking "Please dont steal this car." The person who gets that far wont care.
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It seems to me that they would just need to take the time to figure out
It's not WiFi its see through walls mm waves (Score:2)
It's not WiFi they are protecting against - its "see through walls" mm waves that this will be especially effective against.
From the article :
"I'm working on a material that can absorb a larger range of frequencies. We are capable of making a paint that can absorb over 200 gigahertz."
This will stop Through-the-Wall Surveillance Technology cold. [nowpublic.com]
Since 100 GHz is a 3 mm wave, and 200 GHz a 1.5 mm wave, they much have fairly small (100 micron) aluminum oxide particles in the paint.
Now, the paint will also sto
Could this also enhance the signal? (Score:2)
You should theoretically have enhanced signal quality if you're keeping it within the walls. All that radiated power that would have gone outside will remain inside, so there must be some sort of net increase in power radiated to your computer antenna.
Unless. . . (Score:2)
Unless this compound does something like absorbing the RF, and in the process, attain a slightly higher temperature/thermal energy state. If that's the case, it would be like shining your flashlight on a black surface (most 'black' paint still reflects some light, but I hope you get the idea).
Ahah! (Score:2)
"You or your neighbors may be unwittingly using this already, as most pre-finished wood flooring uses aluminum oxide as a protective coating."
Finally, I can get rid of that kid in the basement!
BAHAHAHAHAHA! PWNAGE!
Usefull in heavily saturationed WIFI areas (Score:3, Interesting)
Where I am there is some WIFI (hidden or not) on every channel. There are large broadcast towers about half a mile from me which have various Internet over 802.11B from service providers.
My WIFI in my home has a hard time with all this. This paint would be a good way for me to improve my in home signal. A lot of my equipment doesn't support the new 5Ghz of 802.11N, so while I have 802.11N APs they do not help much.
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limit my wifi? pah (Score:2, Interesting)
I did however install the Tomato firmware on my router, and use it's brilliant QoS to limit all machines but my own to 56k connections
Until someone opens a window or door (Score:2)
Of course, then everyone in the building dies and there's no more need for the security...
Won't someone please ... (Score:2)
The BBC reports...
My basement does a good job (Score:3, Interesting)
I happen to live in Minnesota, where most homes have basements. Our Comcast cable enters the house through the basement, so I figured it was a convenient place to hook up the WiFi access point. The WAP is sitting on the bottom shelf of a bookshelf I have there.
The net effect is that I have great WiFi signal throughout the house. I have a wood frame house, and WiFi signal is not retarded by normal wood construction. However, I get almost no signal as soon as I step out the back door onto the porch. A few feet away from the house, I can't pick up the signal at all. I've also tested it from the street, and it's like my WAP isn't even there. No, I'm not using any special paints or "Faraday cage" wallpaper.
That's because basements are constructed from cement blocks, which do a pretty good job of retarding WiFi signal. Not to mention my basement is 6-7 feet underground (there are windows at almost ceiling height) and all that dirt also helps block the signal. I figure I'm pretty safe from snooping. Sometimes it helps to just be incrementally harder to get to than the next guy. If you're a wardriver who's interested in free WiFi, my neighbor two doors down is an easier target (his WAP is on the second floor of his house, so he's essentially broadcasting to the whole neighborhood.) Or I suppose you could drive down a block and a half to the coffee shop who runs a completely open WAP.
* And yes, I do use good WAP security, with encryption, long passphrase, MAC filtering, only wired connections are allowed to connect to the admin screen.
No any practical use (Score:2)
Even if the paint blocks radio waves, it would be usable only in windowless rooms without electricity. Radio waves have a property going where you do not want to, and not going where you want.
For example, I know multiple RF-shielded rooms that were very good when they were build in early 1970s. However, one has no problems using cell phone inside of those. To get sufficent protection to GHz rf signals, you must have proper filters in all wires going to room, including all copper network cables and power lin
i already have this on my house (Score:2, Interesting)
after installing a steel garage door, it did a pretty effective job of preventing my garage door opener from working either
Thermite? (Score:2)
I wonder what else is in there to act as a stabilizer to negate the massive fire hazard.
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Thermite is a mixture of aluminum and iron oxide, which is not the same as aluminum iron oxide.
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The "oxide" helps a lot there.
Re:Resonance at other frequencies? (Score:5, Informative)
> What frequencies are not resonant in Aouminum Oxide paint?
The reporter is just yammering. He hasn't the foggiest idea what the word "resonant" means and knows less than nothing about radio. All we can glean from this is that someone has put out a press release about rf absorbant paint, something that has been around for decades.
Re:Resonance at other frequencies? (Score:5, Informative)
Using information in the article I was able to find the actual science paper [acs.org]. It turns out they are able to tune the resonate frequency of this paint. Very cool. However, the it doesn't go all the way down to 2.4 GHz. That's a pretty long wavelength for this process.
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I have a tenant in one of my houses who's trying to figure out how to get good enough QOS from the neighbor's unsecured WiFis (seven routers from a 5db antenna) so that he can drop his phone service. I haven't had the heart to tell him it's illegal.
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this material is an Oxide. Thus it is already "burnt".