Don't worry im still impressed

Does that mean some cans are magnetic and others aren't or am i being thick?
Yes, that's right,
The way I tell new staff is:
All food cans are steel, except the ones made of Aluminium and all drinks cans are alu, except the ones made of steel...
Most drink cans are alu, but most Carling are steel, along with Boddingtons, most Pepsi and Tango. Food cans are steel, with the exception of some (but not all) fish cans (sardines, makerel etc) which are alu. There are also some alu petfood cans - the small gourmet cat food type.
We don't use magnets to sort at the kerbside, it would take too long. We just learn how to tell the difference - partly appearance (like the shiny/matt base), or feel - steel is stiffer and stronger than Alu. We want to be as accurate as possible because Alu is our most valuable product, whereas we don't make any money on steel.
By the way, 'we' are
St Nicholas Fields Community Recyling. I've been a Womble for 3 years next month!