Yes. It is cement.
Some portions of the walls broke apart fairly easily, the rest hammered apart like they were made of... ahem, cement.
These cans were in the wall side-by-side. Some were nice, some were not.
We suppose that some manufacurers used a higher quality of paint than others. ie Penzoil held up the best.
The walls are finally down and all cans that were worth rescuing are in good hands.
All cleaned up. "THANK YA' JESUS" (said with gusto and a southern drawl)
Time permitting, I will be posting pix of some of the cans tomorrow.