Construction and Destruction


Safe-blowing,although not unusual at the beginning of the century, reached its peak between 1945 and the late 1960ís. History has shown that crime increases in post-war years. This can be attributed to the great advances in machine and tool developments in wartime combined with the training of personnel in their use. The use by criminals of oxy-acetylene torches and explosives are cases in point. The major cause however was the weakness of safes in general commercial use in these post-war years, many of which had been made in the previous century and had never been designed to give protection other than against fire and basic tools. This combined with the fact that complacency had not anticipated the levels of losses that they were about to be incurred and the fact that due to munitions production, modern safes were just not available to meet the new levels of risk. The only explosive risk that had been taken into account was from gunpowder, which, being a low explosive was relatively ineffectual.

The illustration (left) depicts a very basic lockcase and chamber from the earliest type of fire-resisting safe which would have been in common use from about 1850, with surprisingly many still in use today. This lockcase would be attached to the back of the door plate by bolts or screws.

The sliding boltwork (coloured blue) is operated by an external handle and secures the door in the frame of the safe , which in turn is held in the locked position by the bolt of the keylock shown (coloured red), and which, when unlocked with the key, would allow the bolts to be withdrawn by means of the handle and the door then opened. To force open such a safe, the bolt of the lock has to be displaced by drilling and punching, or by removing the lock entirely. The most crude but effective means of accomplishing this would be to place a small charge of high explosive into the lock via the keyhole. (picture right). If done correctly the lock would disintigrate without causing any other distortion of the boltwork and the handle would operate as normal.

For gunpowder (blackpowder) to be charged into a mechanism such as this would require that a hole be drilled through the door plate. In the early days this would have been done using either a belly brace or ratchet drill.


This was not always necessary however as in the early days the keylocks were capacious enough to accept black powder in quantities sufficient to remove the lock cap and bolt allowing the boltwork to be withdrawn.

This led to the patenting of a ‘powder-proof lock’ by Thomas Milner in 1854 which was designed in such a way as to allow only the necessary movement of the key, levers, and bolt, the remaining space being blocked by a casting within the lock. They even went further and filled the voids within the lockcase with wooden inserts which effectively prevented the insertion of black powder into the lockcase.

When high explosives came into commercial use at the turn of the Century, it was inevitable that such powerful materials would fall into criminal hands. These pliable gelignites were simply packed through the keyholes as far into the lock as possible followed by an electric or fuse detonator. Depending on the size of the charge, which for the relatively unskilled was dependent on the capacity of the lock, either the lockwould be cleanly removed allowing the door to be opened in the normal fashion,or if excessive, would so distort the mechanism as to render it fast.

The safemakers, as always, responded to each new weapon in the arsenal of the safe-breaker. The Ratner Safe companywere the first when in 1914 they developed their ‘safety bolt,’ or what is now known as an anti-explosive re-locking device. This was a spring loaded secondary locking bolt which would be connected to the main lock, and which, if the lock was removed by whatever means, would be released to re-lock the main bolt work. It was later improved upon in 1918 by a similar device but with the great advantage of working in conjunction with the keylock which put it ‘onguard’ as the safe was locked, and which could only be released by the proper unlocking action of the keylock.

This model, the Grade 3, was installed in most Co-operative branches throughout Scotland and also, to a lesser degree in the ABC Cinema circuit and Glasgow Corporation Baths Department premises. Not one was ever successfully blown open. As the door plate of the Grade3 was drill resistant it was necessary to cut out a small rivet with oxy-acetylene to release the relocker. (see above) Because of the strength of the construction it was usually possible to repair the doors to their original condition.

As the above would indicate, the safe-blower did not have unlimited success. From the newspapers in the post-war years where safe-blowings were being headlined on an average of three times a week in Glasgow alone, it would be easy to misconstrue that all safes were easy prey to the cracksman. Actually the majority of safes in commercial use – excluding banks – were only of fire-resisting quality. At the turn of the century in the Birmingham area alone there were as many as 40 small firms making such safes, and which, through a combination of ignorance and dubious salesmanship, were being entrusted with overnight cash holdings far in excess of their potential capacity to resist.

There were of course many quality safemakers like Ratner whose thief-resistant cash safes were in use in banks, jewellers, and pawnbrokers, where the threat from safe-breakers was anticipated, and where such resistance would also be a requirement of insurers. Another was the Milner Safe Company who, in the London Trades Directory of 1900 claimed to be the largest safe maker in the world. Other well known makers were Tann, Chubb, Hobbs Hart, and Chatwood, all manufacturing safes up to the highest level of resistance of the day.

In the pre-war years door construction fell into two types – for fire-resisting safes the lock and sliding boltwork were attached within a chamber which also contained the fire-resisting compound, the whole being bolted to the back of the doorplate as shown on the drawing below.

On thief-resisting qualities,the lockcase containing the lock and boltwork was formed from an angle-iron flange frame which was heavily riveted to the door plate as shown in the drawing on the right.


In this case the fire chamber was attached separately to the lockcase. It was only in the latter form that anti-explosive devices could be successfully applied as everything except the fire chamber would remain intact in the event of a blowing.

The safe bodies as illustrated are of 12 corner bend construction. This would be mild steel from ¼” to ½” maximum thickness and which, apart from the back plate, was formed from a single sheet of steel. The technique of bending heavy plate did not come into general practice until the late 1800’s.

Prior to this, the bodies were mainly fabricated from wrought iron and all the joints were riveted or dovetailed. (Chatwood actually dovetailed ½” steel plates to form the outer bodies of such safes as their List 2a Quality).


 Construction and  Destruction
 The Explosives
 Some Examples
 Four Petermen
 The Author