If your house was built before 1970, there could be razor blades in your walls. The blades you might find aren’t your common plastic cartridge blades, but the so-called “safety blades” of the early 20th century. These double-edge blades were the only ones available for at-home shaving in the 1950s. Because they were sharp, they couldn’t just be thrown in the trash with the rest of the garbage, so medicine cabinets contained a slot in the back that was used to discard used blades. They would fall into the wall cavity between the framing studs and collect on top of the bottom-plate stud. The idea was that it would take centuries to fill up the space between walls with tiny, single blades, and by then we surely would have thought of another option.
