The disposable cartridge in your portable label maker might contain a perfect copy of every label it's ever printed.

...You...you haven't just been throwing them out, have you?

Recently, our portable label maker (the "Brother P-touch PT-1830 Electronic Labeling System") ran out of labeling tape. After putting in another label cartridge (specifically, the "TZ-231 12mm 1/2 inch Laminated White") and continuing to print, I decided to pop the old, disposable cartridge open with a flathead to see what was inside.

First, a word on the label maker itself. It's a well-made label maker, but it's relatively "low-frills." Most importantly, it doesn't have a "history" function (that is, you can't "recall" all your previous printings), though you can save up to five of your most commonly printed labels with one of the "Favorites" buttons. You'd probably assume the label maker wouldn't keep an electronic log of what was printed unless told to do so with the press of a "Favorites" button, since having it do otherwise would be burdensome and relatively useless.

That "lack of logging" assumption makes sense based on experience with how and why computers log (generally only logging what is crucial to the smooth operation of the software they run or what's important to and/or requested by the user). And since the item's manual doesn't mention any such logging functionality, it's probably a safe assumption to make.

But when you think "logs," don't just think "electronically stored." Because for a machine that's only partially electronic, you'd only be partially right.

The above picture is what's contained inside every cartridge of this type: a physical "negative" copy of every label that it has successfully printed on a single, long, film-like tape. It's not created for logging purposes, per se; it stores these "copies" merely because it has nowhere else to put the rest of the black film-covering that would have become the letters, numbers, and designs you normally print out. So what happens when you throw out your cartridge? To a malicious someone in the know, it's an easy-to-spot cassette with everything you've ever printed wrapped neatly around a spool.

You're probably thinking that you don't print anything too sensitive on your portable label makers. But if you label folders with client names or print IP addresses, usernames and passwords to display on servers or computers (it happens), you're using the label maker for a somewhat sensitive purpose. As for data as sensitive as full names with social security numbers, few would likely ever have to a need to print such information with a label maker, but I can think of at least some situations where it's plausible (such as on HR records, or a person tasked with filling out a number of forms that repeatedly ask for their name, social, DOB, etc.).

Security concerns stemming from the use of printing devices certainly aren't a new phenomenon. Typewriters that use single-strike carbon typewriter ribbon, for example, store every character a user types. Every time a user presses a key, the "type hammer" with the character corresponding to the key the user pressed swings forward, striking both a ribbon of carbon paper and your document. This is necessary to create the printed character on the page. But unbeknownst to some is what's left behind: an imprint of the character you just typed at that location on the carbon paper, which then advances along and is saved on its spool even after you remove your typed document.

Just like the cartridge in our label maker, this ribbon sticks around on a spool merely because it has nowhere else to go; quite the opposite of most computer software's "discard unless instructed to keep" mentality. Of course, this mentality makes sense on a machine that's able to control the transience of the information it processes, unlike a single-use, self-contained label cartridge or carbon typewriter ribbon where that information literally has nowhere to go.

In fact, government employees that worked on sensitive documents in the days of the typewriter were required to lock their typewriter ribbons in a safe at the end of the day (much like we (hopefully) secure our computer data with encryption). Once the typewriter ribbons used by these employees reached the end of their spool, they were burned.

Devices that read and transcribe typewriter ribbons (such as the Ribbon Analysis Workstation by Envisage Systems) are still in use today in government agencies such as Immigration and Customs Enforcement (ICE), according to this article in Government Security News Magazine. The FBI's Questioned Documents Unit(QDU) also has the ability to "examine and analyze typewriter ribbons," and as of 2006, they too maintained a ribbon analysis workstation.

While label makers might not have the same amount or type of data on them as typewriters, the risk is still present when using them in certain scenarios. The next time you're switching the cartridge in your label maker, think about what you've been labeling and determine if you need a more secure method of destruction than simply throwing it in the trash. (Or just pop it open and check for yourself!)

For those interested in further reading on printing privacy concerns, check out this interesting PC World article on how some documents printed with many standard printers reportedly contain information, including their printer's serial numbers (an effective way to tie documents back to a single, physical printer), encoded in barely-visible dots on the printed page. Then head over to the Electronic Frontier Foundation for a number of resources, including a preliminary research paper with detailed information and examples of these "printer dots" in action.

As soon as you commit information to a medium other than your memory, it's very easy to lose positive control over that information. This will happen almost instantly unless you are able to understand and control every facet of the both the commission to, and the storage of, that medium. Keep that in mind.

But don't write it down.