If your antenna has been up on the roof for any amount of time you may notice that it’s starting to turn black. If you go up on the roof you may be able to wipe off some of this black dust but some will stay. Should you be worried that the antenna is already wearing out?
Good news, no.
That black dust sticking to the keyboard is called “oxidation” and it’s perfectly normal. It’s akin to a penny turning green, or sort of like rust. However, unlike rust, it’s not going to corrode through your antenna. Oxidation happens because your antenna is made of aluminum and aluminum doesn’t like to exist in its pure state very much. When you find aluminum out in nature it’s combined with some other element, but for antennas it’s converted to pure aluminum so that it does a better job as an antenna.
So, it’s perfectly natural for aluminum to try to return back to a form like one you’d find in nature, so the atoms of aluminum combine with atoms of oxygen in the air (helped along by some water in the air and the electrical current of the radio waves) and turns the aluminum into aluminum oxide. That’s what that black stuff is.
Unlike iron oxide (rust) aluminum oxide is very stable. A layer of it on your antenna’s actually a good thing — it protects the antenna from corrosion instead of causing it. And what’s even better… aluminum oxide does a good job of pulling in radio and TV signals, almost as good as pure aluminum. The only reason they don’t make the entire antenna out of aluminum oxide is that it’s not as strong as pure aluminum.
So, don’t worry about that black dust, it’s actually protecting the rest of the antenna. Don’t clean it off, it will just come back.