TikTokers say they're finding rusty razor blades behind their bathroom mirrors. If your home was built before 1970, you might have some, too.

• TikTokers are finding razor-blade slots in their bathroom mirrors and medicine cabinets.
• The slots are common in homes built before 1970 and would let people "dispose" of their old blades.
• The used blades would pile up in a space behind the bathroom mirror, not the trash.

Homes built in decades past sometimes have their quirks - from hidden showers to buried indoor hot tubs.

Recently, some TikTok users have gone viral after claiming that they've unearthed old razor blades in the walls of their bathrooms.

The old razor blades seem to be a result of small slots in some medicine cabinets common in homes built before the 1970s. Before plastic, disposable razors became the norm, the slots were meant for people to "dispose" of the used blades, according to Reader's Digest.

The slots would lead to a hole in the wall, causing the blades to pile up behind the mirror.

@_angelicagomez_

Did that just happen? Lol Why would they put them in the wall? ##DIY ##RentalHack ##SmallBathroom

♬ Vintage girl carlyknighht - Carly Knight

TikTokers are showing the old razors they say they're finding

One of the first TikTokers to post about finding the vintage razor-blade slot in her home was user @carlyknight, who goes by Carly Knight on the app.

According to her TikTok videos, after posting a tour of her 1950s-era home, one user commented that she probably had a razor slot in her bathroom. Knight later showed that in her medicine cabinet, there was, in fact, a small slot labeled: "Used razor blade disposal."

@carlyknighht

anybody else’s house have this? ##fyp ##greenscreen ##MyCostume ##exprESSIEyourself

♬ Vintage girl carlyknighht - Carly Knight

Since Knight posted the video, it received 3.8 million views, and TikTokers joked about the design in the comment section.

"People in the '50s like, 'Nah we'll all be gone when this becomes a problem,'" one user wrote of the used razor blades.

Another added: "People back then were so 'out of sight, out of mind,' like it doesn't just disappear, Beverly."

More than 150 people have since used Knight's sound clip on TikTok to show their own discoveries of razor slots in homes they say were built in the 1920s to the mid-1970s. Some users, like @noah_quay, have even removed the cabinets to uncover dozens of rusty, used razors.

Melissa Alicea saw Knight's video and immediately checked her bathroom.

Alicea told Insider she's lived in the apartment building, which was built in 1966, for seven years, but she never noticed the slot and the discrete writing above it that reads "razor blades."

@missmouse2383

Lived here 7 years, noticed the slot, never read the “razor blades” part. ‍♀️

♬ Vintage girl carlyknighht - Carly Knight

"I must have looked at it a thousand times before, but it never registered," she told Insider via Instagram. Since she's living in an apartment that she rents, she said she hasn't tried to remove the cabinet to check for old blades.

Homes built before the '70s may still have razor slots

According to Reader's Digest, blade slots were prevalent in homes built before the 1970s, when safety razors were a common choice for household use.

In 1903, Gillette introduced the first modern, double-edged safety razor, which was a safer, easier option than using a straight-edge razor at a barbershop, according to Gizmodo.

Safety razors gained popularity, but homeowners were faced with the challenge of how to dispose of the blades.

Throwing them in the trash had safety issues, and the blades couldn't be burned, according to Reader's Digest.

That's why builders started adding a slot that would allow people to drop their used blades in a gap between the wall's studs. The spaces were large enough to hold thousands of razors, allowing homeowners to essentially forget about the problem.

But today, people living in or remodeling these homes are discovering the quirky feature, and potentially the old razors left there from previous owners.