Ter,
You learn something new everyday. Maybe. I dug out my canteen cup and took a magnet to it. No go. So, ASSUMING (as I am), that the thing is made of stainless steel, not all SS's are magnetic.
My apologies if I insulted your intelligence. I thought anything called "steel" would be magnetic, even if there is a "stainless" in front of it. Some "stainless steels" are magnetic, some, apparently, aren't. Go figure.
Any metallurgists out there who can explain this? Slowly? In laymen's terms?
Take care,
Andy