Lock Impressioning – Building Something Out Of Nothing

A locksmith presenting a key for a lock, like a magic trick!

Lock Impressioning – Building Something Out Of Nothing

So we all know you can take just about any normal house key to a hardware store and have it duplicated for next to nothing. But what happens when for whatever reason you need a new key made, but all you have is the lock? Many might assume they’re out of luck and will be forced to replace or rekey the lock after having a locksmith pick it if it’s locked. It turns out though, that a skilled locksmith can make you a new key using only the lock and an advanced technique called lock-impressioning. Impressioning a lock involves inserting a blank key into the lock, and manipulating it in such a way that the lock leaves specific markings on the key. By studying these markings, the locksmith can determine the interior shape of the lock, and accordingly, how to cut the new key to fit it.


The Tools

wrench to torque key in lock

file to make cuts in keysIn this process, something is used to grip the key (vise grips are a popular choice) and heavy torqueing pressure is applied to create the markings. This generally needs to be repeated several times before the key works, with small pieces being removed each time in the places indicated by the marks.


The cuts in the keys are made using a small, cylindrical file, with a long cone shape on one side, ending in a fine point. They are around six inches long, and the popular ones are typically of Swiss or Italian origin. The fine point allows the locksmith to make focused cuts above the markings, and remove only small amounts of material at a time; limiting the risk of cutting too deep and having to start over.


The Keys

brass keyIt’s important to use the right material for your blank keys that will be both soft enough to be effectively marked by the process, but also strong enough to withstand the repeated torqueing in the lock. Brass is the most popular option, with brushed (not-shiny) finish being preferable. If you can only get the shiny kind though, the edges can be filed down to make the markings more visible. Many also recommend filing the blank to a knife edge, which often makes obtaining clear markings much easier.

Keys that are made through impressioning will be functional for a time. Their long-term viability is questionable however, as the repeated process of torqueing them in the lock weakens the metal significantly. The lifespan of an impressioned key can vary depending on the type of blank and the exact method used by the locksmith to obtain the markings, but generally speaking, one should plan to replace an impressioned key as soon as possible. Otherwise you’ll just be doing this again in a month, only next time you’ll have to extract a broken key first. A locksmith can even round the measurements of the key to the nearest factory standards, so your replacement keys will fit the lock like brand new ones from the factory.

The Locks

handle lockImpressioning is considered a covert and non-destructive technique. Covert meaning it’s use cannot be detected through normal daily use of the lock (though it will still be revealed by a forensic examination) which looks for certain tell-tale marks on the interior of the lock. Non-destructive simply means that the technique can be done without taking apart or damaging the lock. This is typically the case with most locks, though occasionally older or more fragile locks can actually suffer damage as a result of the stress put on them by impressioning.




Car Locks

Car lockAuto locks can present some interesting challenges for impressioning. There is a small number of automotive locks, mostly on newer cars, that are extremely fragile, and cannot survive the impressioning process. Some of these locks will be damaged by the simple action of inserting a blank key. Other times, different locks on the car may be keyed to varying degrees of security. So a key impressioned from the trunk lock may not open the door, and a key made from the door lock may not turn the ignition. A key impressioned from the ignition should work in any lock on the car, however doing this risks costly damage to the transmission. Of course, all newer cars use transponder chip systems, so an impressioned key will only be good to open the doors and trunk. It will function as a key in the transmission. But most modern cars have a secondary electronic lock in the transmission, and turning the key in the lock is not enough to start the engine without the presence of a properly programmed transponder with a code purchased from the car manufacturer.


High Security Locks

High Security LockIn addition to car locks, high-security locks also require a locksmith to go above and beyond the normal methods for impressioning. High security locks are exactly what they sound like. They are typically based on traditional lock designs, but incorporate many additional and often complex features, which are designed to thwart specific methods for surpassing locks including picking, prying, brute force, and more. Certainly, these companies have also succeeded in making these locks more difficult to impression than standard locks. However, due to the presence of traditional pins, high security locks can generally still be impressioned by an expert who can obtain a blank. Herein lies an additional hurtle for impressioning high security locks. The lock company’s only means of combatting this so far is by doing their best to limit and track the availability of the key blanks to their locks.