Turn a padlock over and you’ll probably find it: a tiny hole on the bottom, separate from the keyhole. It isn’t a second keyhole, and it isn’t a manufacturing defect. It has a precise job, explained by industrial supplier Monroe Engineering, and knowing it changes the way you care for every lock you leave outside.
In short
- The tiny hole is a drainage port: water that gets inside the lock can run out.
- That limits rust and corrosion on the parts inside.
- It can also take a small drop of lubricant.
- Master Lock recommends cleaning and lubricating a padlock every 3 to 6 months.
What the hole is for
The Argentine news site TN put the question in front of a wide audience under the headline “Pocos lo saben” (few people know). The answer is simple. According to Monroe Engineering, “the small hole on the bottom of padlocks acts as a drainage port.”
A padlock lives outside: on a gate, a shed, a gym locker or a bike chain. Rain, snow and humidity get into the keyway. Without an exit, that water would sit inside the body, against the small parts that make the lock work. With the hole, Monroe explains, “moisture will drain out of the small hole while subsequently minimizing the risk of rust and corrosion.”
Its two other uses
- Lubrication. Moving parts can stick over time, and Monroe notes that “you can apply a small amount of lubrication through the small hole and into the padlock’s body.”
- Locksmith access. Depending on the model, the same article explains, a locksmith may be able to open the lock by inserting a special tool through the hole.
How to keep a padlock working
Master Lock gives precise care advice:
- Every 3 to 6 months, clean and lubricate the lock. In very dusty or corrosive environments, every three months.
- Use a PTFE lubricant, applied “sparingly” to both the keyway and the shackle. The brand says to “NEVER use dry graphite, or a silicone lubricant.”
- Work it in: tap the lock, open and close it several times with the key, wipe off the excess and let it dry.
Master Lock adds that “regular lubrication will also help minimize freezing in cold weather environments,” which matters as winter approaches.
The limit
The hole drains water, it doesn’t keep it out. A lock left for years without care can still seize up, which is why Master Lock asks for more frequent care in dusty or corrosive places. And since water runs down, the drain does its job best when the bottom of the lock faces the ground. Never plug the hole with tape or glue, and don’t use it as an excuse to skip the cleaning Master Lock recommends.
Everyday objects are full of design details like this one, from the two holes in clothespins to the gap in public toilet seats. And if your keys are dull or rusty, see why people are spraying vinegar on their keys.
A tiny hole, a drop of lubricant and a lock hung the right way. That’s the trick.
