Ask Mr. Technology
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Q: I’ve heard there are ways that shredded documents can be put back together. Is that really possible?
A: Well, it depends.
When the U.S. Embassy in Tehran fell in 1979, a great deal of highly classified information was compromised. Part of the problem was that the embassy used low-quality shredders. The Ayatollah gathered a bunch of conscripted Iranian weavers, long used to working with 400 knots-to-the-inch Persian carpets, who were able to re-create the documents.
It makes you think: If carpet weavers could piece together top-secret papers, what could technicians equipped with modern digitizing and pattern-recognition technology do?
Bob Johnson, president of the Phoenix-based National Association for Information Destruction, says that document destroyers use a variety of methods. Some methods render documents permanently unreadable, while others yield results that could be reconstructed using high-tech equipment and software. In general, he adds, document destruction devices fall into two groups. The first type is the common strip-cut shredder that cuts a sheet of paper into a jumble of about 20 parallel strips. Strip shredders are fast and comparatively inexpensive, but companies such as Houston-based Churchstreet Technology or Fraunhofer IPK of Germany (or a group of Iranian weavers, for that matter) can reconstruct strip-cut shreds if you’ve got enough money.
The second group includes the cross-cut shredders and paper pulverizers that commercial document destructors use. Shred Right Inc. of St. Paul uses opposing cutters to chop paper on perpendicular axes. According to Shred Right’s Chris Judd, this type of shredder reduces documents to small, unrecoverable bits.
Judd adds that commercial data devourers gulp and pulverize not just paper, but computer drives, manuals, uniforms, and anything else that falls into their always-hungry maws. A typical commercial shredder, powered by a 75- to 200-horsepower motor, can turn tons of documents per hour into dust.
There are other subtypes in the commercial shredder category. The “hammermill” uses hammers that whirl around at 1,800 rpm, pounding paper through a sieve into pulp. Another type of shredder is the “pierce and tear,” which uses two slow moving, counter-rotating gears. Slow, yes, but the motors which turn them produce such high torques that their hardened gear teeth can take on anything short of a fully grown redwood.
Johnson says these big machines are just about unstoppable. “You could put a pallet of cinder blocks through these and they wouldn’t burp.”