Paper Shredder - Types

Types

Shredders range in size and price from small and inexpensive units meant for a few pages, to large units used by commercial shredding services that cost hundreds of thousands of dollars and can shred millions of documents an hour. Some shredders used by a commercial shredding service are built into a shredding truck.

The normal small shredder is an electrically powered device, but there are unpowered ones such as special scissors with multiple blade pair and shredders which are hand-cranked.

These machines are classified according to the size and shape of the shreds they produce. (As a practical matter, this is also a measure of the degree of randomness or entropy they generate.) Shredders can range in size from standard scissors and other hand-operated devices all the way up to truck-sized shredders. There are also shredder selector sites that can help consumers choose a shredder that is appropriate for their needs.

• Strip-cut shredders, the least secure, use rotating knives to cut narrow strips as long as the original sheet of paper. Such strips can be reassembled by a determined and patient investigator or adversary, as the product (the destroyed information) of this type of shredder is the least randomized. It also creates the highest volume of waste inasmuch as the chad has the largest surface area and is not compressed.
• Cross-cut or confetti-cut shredders use two contra-rotating drums to cut rectangular, parallelogram, or diamond-shaped (or lozenge) shreds.
• Particle-cut shredders create tiny square or circular pieces.
• Cardboard shredders are designed specifically to shred corrugated material into either strips or a mesh pallet.
• Disintegrators and granulators repeatedly cut the paper at random until the particles are small enough to pass through a mesh.
• Hammermills pound the paper through a screen.
• Pierce and Tear Rotating blades pierce the paper and then tear it apart.
• Grinders A rotating shaft with cutting blades grinds the paper until it is small enough to fall through a screen.
• Papermasher bag Specially designed bag used to safely dispose confidential documents. Simply fill the bags with documents and place them in your washing machine. The paper will be mashed to a pulp and become unreadable.

There are numerous standards for the security levels of paper shredders, including:

• DIN 32757
  • Level 1 = 12 mm strips OR 11 x 40mm particles
  • Level 2 = 6 mm strips OR 8 x 40mm particles
  • Level 3 = 2 mm strips OR 4 x 30mm particles (Confidential)
  • Level 4 = 2 x 15 mm particles (Commercially Sensitive)
  • Level 5 = 0.8 x 12 mm particles (Top Secret or Classified)
  • Level 6 = 0.8 x 4 mm particles (Top Secret or Classified) (unofficial extension of the DIN 32757-1 standard)
  • Level 7 = 0.8 x 2.5 mm particles (Unused by most organizations, titles one model of shredder, the SEM 344)
• United States Department of Defense (DoD)
  • Top Secret = 0.8 x 11.1 mm (1/32" × 7/16") no longer approved after 1 October 2008 for U.S. government classified documents
• United States National Security Agency/CSS 02-01 = 1 × 5 mm required for all U.S. government classified document destruction starting 1 October 2008.

Historically, the General Services Administration (GSA) set paper shredder guidance in the Interim Federal Specification FF-S-001169 dated July 1971 which was superseded by standard A-A-2599 for classified material which was canceled in February 2000. GSA has not published a new standard since.

There are alternative shredders that use combustion, chemical decomposition, or composting for disposing of the shreds.