I bought a canned pineapple and finished the content. The part of the can that is in contact with the liquid appears like galvanized steel (crystalline surface or spangles sort of appearance), while the part that are not looks pretty shiny like the outside of the can.
I then washed the can and added water to it, and heated the bottom of the can with a butane torch. After the water was heated up, I removed the torch and left it out for a while.
When I came back later, I emptied the water but noticed that the bottom rim of can had quite a bit of rusting. After inspecting it closely, I found that there are spots of (concentrated) rust on the cylindrical wall of the can as well. There are also light patches of rust on the inside bottom of the can. The seam on the cylindrical wall that is in contact with water is also badly rusted.
I thought galvanised steel only rusts when the layer of galvanisation wears out.
So, is the tin made with galvanised steel?
If yes, why are there concentrated spots of rust on the wall and other rusting?
If not, why does the inside of the can look like galvanised steel?
And BTW, why does the emptied and washed can smell "metallish"?