I need to start putting things up on the walls in our new apartment we've moved to and a couple of light duty things were easy enough but I have to put up some shelves and things now that are 20 pounds and more and I feel like I need to have a better sense of what these walls are made of. I saw online that peeking behind a light switch could be useful but you'll see in the photos that it was hard to see much. Some other holes where cables pass were more telling.
Sadly I don't know a lot about this, but I can tell you with the few holes I've made for light duty things like I said (a small mirror, a little kitchen shelf) the walls are really sturdy, they don't crumble like that cardboard-y drywall in modern apartments. I can also tell you these walls are all original from 1931 if that helps place the material. The drill holes were super clean, the wall feels about an inch thick and hollow behind.
So if any of you with more expertise than me could help me out with identifying the walls and then what my anchor options are. Most things will be 10-20 lbs but I do have a 35lb wood framed mirror that we'd like to put up again in this new place. A hardware store salesperson told me to use the anchors that are beige and drill themselves into the wall that you then screw into but I don't see how that kind would ever be able to cut into these walls.
Thanks for any advice!