Living in an apartment building, I can spot about twenty active Wi-Fi networks at a time. And the worst part is that they can all see me, too.

While we've had RF-blocking paint to cellphone signals for some time, manufacturers have been thwarted when attempting to stop higher frequencies, like we have on home networks.

Now a team of researchers from the University of Tokyo has developed an aluminium-iron oxide that blocks radio frequencies up to four times beyond existing anti-RF technologies. The paint puts out a magnetic field that resonates at the same frequency as the electromagnetic wave (in this case, a radio frequency) you're looking to block.

The good news is that the material shouldn't be expensive to produce. Right now it's estimated to run $14 per kilogram. Assuming our math is correct, if the average gallon of paint runs 2 pounds, then a can of Wi-Fi blocking paint would be $50 to manufacture. That's not super cheap, but neither is the lifetime of blackmail after your neighbor deciphers your network password and threatens to show the world your earnest, self-shot modeling portfolio. [PCWorld via Unplggd]

Send an email to Mark Wilson, the author of this post, at mark@gizmodo.com.