Historical and technical insights about secret padlocks

Padlocks have a long history behind them. They are one of the most enduring security tools in the world.

To make what they were trying to protect safer, padlocks also became more and more complicated ... puzzles in their own right.

We managed to track down some news of secret padlocks already in ancient Rome.

If the Romans wanted not to send sums of money, do so by insuring the "shipment" with very special secret padlocks!

Nobody could have thought that there were padlocks dating back to the Roman Empire, but thanks to some collectors who have decided to dig, pieces have been found buried for more than 2000 years.

All the padlocks found have distinct characters. Usually produced were in bronze and reproduced the face of a deity. Janus, god of moments of transition and passage, was a heavily represented subject.

The faceplate was hinged to the top of the lock and, when turned over, could reveal a keyhole, the key of which was sometimes also worn separately.

The key alone, however, was not enough on its own to open the lock; the locks also hid one or two tiny plates that must be moved before opening the circle of the ring.

But the key alone was not enough to open one. The locks also concealed one or two tiny plates or switches that must be moved before the shackle, the circle of the ring, opened.

The earliest mask locks, as they also come close, have fewer switches and appear to come from regions influenced by Celtic culture, such as Aquileia, to the Julian Alps. The hypothesis is that the locks are adapted become more complicated as the Romans take off.

The small locks are thought to have been primarily used to act as tamper-proof seals. People who send money from one place to another protect themselves in this way, revealing the secret to open the padlock only upon transfer.

Indian mask padlocks

With the end of the Empire, the use of mask padlocks also ended and although none of the examples we have received are functional, there are replicas to study the mechanism.

Indian mask padlocks fig 4-5-6

Since the history of these particular tools has some not inconsiderable gaps, we must then take a leap directly to the England of the Industrial Revolution. Moving from an economy very different from the agricultural one, blacksmiths began to design portable locks, or padlocks, increasingly ingenious to respond to the continuous increase in thefts.

In 1778, Robert Barron invented the cup lock: the bolt gives way, causing the lock to open only if the lever is raised to exactly the right height. And the Barron lock had two of these super precise levers

Jeremiah Chubb then improved the Barron lock in 1818. He incorporated a spring capable of holding any lever raised in an incorrect place. This made the lock even more difficult, but also allowed to understand if there had been any tampering attempts.

Around 1850, the so-called “Scandinavian” padlocks also appeared. The cast iron body was embellished with a stack of rotating discs. Each disc had a central cutout to allow passage of the key and two notches cut out on the edge of the disc. It was therefore necessary to align all the discs to slide the lock.

At the same time, CAST HEART padlocks, more resistant to corrosion than the Scandinavian, with the lock body cast in brass or bronze sand and a safer lever mechanism, also became popular. Excellent for their economic cost and their ability to withstand dirty, wet and icy environments.

The famous Japanese Hanayama company has his own Cast Heart today.

With greater accessibility to electricity and new processing techniques, it has been possible to create new padlocks with different opening mechanisms, as well as increasingly convoluted lock puzzles to the delight of all fans and thanks to the brilliant minds of the various creators.


Secret Padlocks: