In alt.home.repair, on Sat, 27 Mar 2021 20:01:01 +0000, just plain sue
wrote:

Have an old house, circu 1880's, when then or later canvas was hung in rooms and wall paper hung on canvas. The canvas was nailed to the walls of the room & nails are very difficult to remove. Help! Thought a magnet would suffice to run across the wall boards???

"Run across" is very ambiguous. Your meaning is clear from your subject
line, but I and some others often don't read subject lines. Would you
write something for school or publication and put one of the essential
points only in the title and not in the body?

Grampy and Ed are both right. As to crowbars, there is something
between a claw hammer and what I learned to think of as the primo
crowbar. Here is one:

https://www.homedepot.com/p/Stanley-...515K/100093815

More powerful than a hammer, but not heavy enough to put accidental
dents in your wall, if you put a piece of metal or wood underneath as Ed
said.