The scrap yard here just counts any very thin steel as tin. It don't matter if it actually is or not, sheet metal that is not aluminum and not thick enough to get classified as #1 or #2 gets counted as tin. Appliances, car bodies, steel tools, all get counted as tin. Car frames and things like that get counted as #2 long iron and pay more, and the really thick stuff like car rotors, I beams, etc. get labeled #1 long iron and pay even more.



For that reason I usually just keep a magnet with me. If the magnet sticks, it's steel, if it doesn't, it's aluminum. Copper and things are easy to tell apart visually, and I usually do the heavy steel loads (#2 or #1) as separate trips to avoid confusion, unless it's just a little bit, in which case I just unload the bulk of the load first, weigh empty, and then hand carry the items over to the scale where they weigh pop cans and stuff.