Padlocks: A History

Padlocks: A History

If you’ve ever tried to pick an old combination lock or padlock, you know it’s a bit trickier than you would expect. Behind every lock and key, there’s a story of evolution. While locks are extremely common today, they were a commodity in the Roman Empire and remained such for many centuries after. Where did the padlock originate?

Rise of the Roman Padlock

The oldest padlocks known to archeologists and historians originate at around 500 BCE with the Romans. Iron locks held a bolt in place and were manipulated with a key. The most common Roman lock had two parts: a rectangular body and a separate ward spring.

The key for the lock was very simple. A flat and rectangular piece of metal was bent at a 90-degree angle. On the end, a small hole big enough to maneuver the corresponding lock spring would latch on to disengage the lock.

The Spread Via Chinese Trade Routes

The Romans didn’t keep the locks to themselves for very long. Trade routes with Asia spread the use and knowledge of the locks via merchants of the day. China used these locks throughout the empire by 25 CE. The Chinese empire began making its own locks using bronze instead of iron. Historians aren’t quite sure how, but the usage of these locks also spread to the Vikings circa 850 to 1000 CE.

Smokehouse Padlocks

In England, the use of a smokehouse quickly spread through the countryside. With this trend, smokers noticed their stores were susceptible to theft from animals and fellow citizens alike. As a result, the smokehouse padlocks were born and widely used. These padlocks return to the original Roman material: iron.

With these padlocks, keys also evolved into more specific models. In Roman’s day, anyone with access to a forge could make a key for the padlock. However, smokehouse padlock keys were designed with notches that must specifically fit the original lock. While the security features weren't flawless, it was a marked improvement on the age-old keys from the Romans.

Scandinavian and Cast Heart Locks

In the 1800s, Christopher Polhem, a Swedish inventor, created the Scandinavian padlock. Made of cast iron, the locking mechanism included rotating disks. The grooves in the disks and keys matched up precisely. The patent lasted from 1871 until the 1950s for a century of production.

After the Scandinavian model, the cast heat padlock came onto the scene. With its bronze and brass construction, the cast heart lock was more weather resistant. It had a keyhole cover to prevent weather and critter damage. They were easily mass-produced, making them more accessible for the average consumer. Because of the key cover, these locks were favored by railroads and industrial businesses.

The Rise of Industrialization

Industrialization made it much easier for previously laborious tasks to be completed quickly. As a result, the locksmith equipment saw a massive boost in accessibility, affordability, and design. Solid metal locks were suddenly easier to produce. In fact, it became cheaper to make sturdy locks from solid metal.

Following this initial period of industrialization, many inventors and locksmiths took a crack at improving the lock’s design. Eventually, the modern padlock came into play, but there were several missteps in the mean time. For example, die-casting was used briefly in the 1930s, but the cheaper method failed to provide dependable quality for consumers.

Locks have steadily gotten more secure as technology continues to advance. These days a lock can require a fingerprint, eye scan, key card, code or an eclectic combination of the aforementioned. Next time you choose a padlock for your project, think about the history behind it as well as the security.