"irony" aluminum vs aluminum

You must have had iron brackets or hardware on it. If it sticks to a magnet, it needs to be removed.

I'm sure somebody can give a more technical answer, but it has to do with the actual aluminum alloy. Some material does have some magnetic property to it--a magnet will stick, but not strongly, even though it's aluminum. That's why (or because), it's iron-y.



On edit: Hmmpf. The above is what I was told at the yard once about what I thought was an aluminum storm door, but got paid as irony aluminum. (It was otherwise clean of ferrous hardware.) After some research, I can't find anything to support that. So, never mind...