However, the inks used to print the labels have been found to contain elements such as Iron, Nickel and cobalt, which are indeed easily magnetized. Further, while the substrate is 99% aluminum, it may also contain small amounts of the ferrous material listed above.
Although this is total and utter hogwash, it keeps being repeated.
(a) Iron, nickel and cobalt do occur in printing inks, but they are not particularly common.
(b) They are present not as metals but as
compounds, and as compounds their magnetic properties are altered. For example, only one of the oxides of iron, the double oxide magnetite (never used in conventional printing inks, by the way), is ferromagnetic (able to be magnetised). The much more common ferric oxide (a.k.a. rust) is not at all magnetic.
(c) I love the hedge - aluminium "may" contain small amounts of the ferrous material. In fact, any such impurities are
'way lower than that. One of the first thing they do with bauxite (aluminium ore) is get rid of the iron:
http://www.webelements.com/webelements/elements/text/Al/key.html
Pure aluminium is then made electrolytically, which gives a very high purity. The aluminium used in CDs is very pure (probably the purest commercial grade, 99.99%).
And, yes, I have tried demagnetising my CDs and yes it doesn't work.
