21 Locksmithing: What is "impressioning"?
Description
This article is from the Locksmithing FAQ, by Joe "Spike" Ilacqua spike@indra.com and Henry Schaffer hes@ncsu.edu, major data collection effort by Scott Anguish sanguish@digifix.com with numerous contributions by others.
21 Locksmithing: What is "impressioning"?
Impressioning is a technique for opening a lock by making a key out of
a key blank for the lock. The blank is filed to fit; the place and
amount of filing depends upon small marks left on the key blank by the
pin tumblers. The procedure starts with smoothing the key blank with
fine abrasive paper or a very fine file to remove any marks or
scratches and to leave a surface which will show the marks. The key
blank is then inserted into the lock and the blank twisted from side to
side and rocked up and down. The blank is removed and inspected for
marks and a shallow cut made with a file on the mark closest to the tip
of the blank, or on the most prominent mark. (There are several systems
for determining which mark should be cut and for the correct way to
twist and rock.)
Repeat this for the same position until the tumbler doesn't leave any
mark on the blank and then move to the next pin. When the last cut is
made the lock should open with the newly cut key - assuming that the
interpretation of the marks and the cutting has been done right.
The advantage of impressioning for opening a lock is that it creates a
key for that lock. But the process is slow and requires a fair amount
of skill. With expert skill levels, the process is considerably
faster. There are a number of special pliers made to hold the blank
and make it easier to give the proper twist with rocking that will mark
the blank. The marks on the blank are difficult to see and you must
start with a blank that fits the lock. (Or several blanks, as this
doesn't always work the first time.) Impressioning may not be as quick
and easy as picking the lock. Picking a lock often leaves tell-tale
scratches on the tumblers and plug that won't happen with
impressioning.
A manual on impressioning by Mark Wanlass is available in the ftp archives
of indra.com - ftp.indra.com:/archives/alt-locksmithing/impressioning
A web version is available at:
http://www.gregmiller.net/locks/impress.html
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