How do stickers that fade to transparency work?

January 24, 2007 8:18 AM

At my (security-sensitive) work we all get badges. Sometimes we leave them at home. Sometimes we need to bring a visitor in. Then we get temporary badges. These badges have an interesting fading sticker on them. How does it work?

The sticker is actually in two parts, which I've seen assembled thusly: First, a red "EXPIRED" sticker with lots of bright red lines is placed on the plastic badge. Then a white sticker with the division name is affixed directly on top of that one.

As the day progresses the "EXPIRED" text becomes more and more visible. I've not yet had the gumption to take one home and see if the white sticker fades completely, but it appears that is what would happen. How does this work?

I asked one of the receptionists that passes them out, and he said that the red ink was bleeding into the white sticker. I find this implausible for two reasons: the sheets with the red stickers on them are stored folded and have no protective covering for any wet ink, and generally the backs of stickers are pretty impermeable to all but some nice solvents (at least in my experience) that would cause the adhesive to fail.

In addition, the red and white stickers become permanently bound together (I futzed with them at work a bit), but it's trivially easy to remove the red sticker from the card itself (good for the staff as they clearly have to do this every day).

Thanks in advance!

posted by Xoder to technology (26 comments total)

PS: I have Googled all over the place and I can't even find a place where I could buy "fading stickers". Most stickers boast their anti-fading capabilities.
posted by Xoder at 8:20 AM on January 24, 2007

It's possible that the covering of the red sticker and the backing of the white sticker have chemicals in them that react to cause the white sticker to become gradually more translucent.

It's also possible that the white sticker has something in it that makes it become gradually more translucent as it's exposed to light.
posted by cerebus19 at 8:27 AM on January 24, 2007

A guess: light sensitive ink?

Do you have a picture of the different states of this sticker?
posted by scalespace at 8:27 AM on January 24, 2007

Next time the security guard puts the badge together, see if the white sticker is originally kept in a light-tight or air-tight bag or drawer. If the white dye in the sticker is photosensitive or sensitive to air, it might degrade on being exposed to UV or visible light, or air.
posted by Blazecock Pileon at 8:28 AM on January 24, 2007

The system is called TIMEbadge. I'm looking to see if I can find how it actually works.
posted by edgeways at 8:31 AM on January 24, 2007

Interesting tidbit.

The TIMEbadge feature is best suited for applications where temperatures consistently range from 65F to 75F. Colder temperatures will lengthen the time for the pink bars to appear; warmer temperatures will shorten the time to reveal the pink bars.

posted by edgeways at 8:33 AM on January 24, 2007

See here - light sensitive ones. I'd bet on light sensitive as they're harder to fiddle. An air sensitive one could be covered with a thin film, but you can't hide a security badge from light without rendering it useless as a security badge.
posted by edd at 8:34 AM on January 24, 2007

where temperatures consistently range from 65F to 75F.

This indicates, to me, that it is indeed a chemical reaction between the two "plys".
posted by muddgirl at 8:37 AM on January 24, 2007

edd - those light sensitive ones don't seem to be time-dependent. They merely indicate when the badge leaves the building.
posted by muddgirl at 8:38 AM on January 24, 2007

The TIMEbadge feature is simple and easy to activate:

• peel off the special backing material to expose the adhesive between the two plys.

• press the two plys together.

Once activated, the expiration process cannot be stopped or reversed. Even if an attempt is made to separate the two parts, the TIMEbadge will continue to change color.

Sounds like a chemical reaction initiated by a compound in the adhesive?
posted by Blazecock Pileon at 8:41 AM on January 24, 2007

Just out of curiosity - what problem is that solving?
Can't you just give a pink badge to a visitor with his/her name and the date on it in permanent marker, then take it away when they leave the building again? The pink badge would be sufficient to keep from being hassled inside the building, but not for original entry, so you couldn't take it home and use it again. The pink badge issuing would get faster after the first time if you issued an access list daily, with new badge issues added and expired ones removed.
It is kind of neat, but at the same time, wtf?
posted by ctmf at 8:42 AM on January 24, 2007

Each TIMEbadge consists of a specially coated white adhesive FRONTpart and a BACKpart that is pre-printed with time-release ink. Once the FRONTpart is applied to the BACKpart, the TIMEbadge is activated. The result is a gradual color change that signals expiration when completed.

from here
So the explanation. "It bleeds through" is kinda correct.
posted by edgeways at 8:43 AM on January 24, 2007

scalespace: "Do you have a picture of the different states of this sticker?"

No cameras allowed at my work, sorry.



edgeways: "The system is called TIMEbadge."

That appears to be exactly the same system, although we have our stickers on plastic hanging (credit card-sized) badges, and the stickers themselves are about 0.75"×2"

edgeways: "

Each TIMEbadge consists of a specially coated white adhesive FRONTpart and a BACKpart that is pre-printed with time-release ink. Once the FRONTpart is applied to the BACKpart, the TIMEbadge is activated. The result is a gradual color change that signals expiration when completed.

from here
So the explanation. "It bleeds through" is kinda correct."

And on preview, teh winnar is you!
posted by Xoder at 8:46 AM on January 24, 2007

Of course, once a visitor has a good look at the badge, unless there is some difficult to reproduce graphic/font he then can just order up a stack of TIMEbadges himself and have quite a lot of easy to use temporary access to the site. They even come in Month length versions.
posted by edgeways at 8:55 AM on January 24, 2007

then take it away when they leave the building again

And how exactly are you going to do that? Stop and frisk every single person leaving the building? If I had one, I certainly wouldn't bother dropping it off at the desk as I left. This seems like an elegant and useful solution.
posted by languagehat at 8:57 AM on January 24, 2007

Doesn't matter if you drop yours off on the way out or not. Making some attempt to recover it, if only a "drop here" box by the out door, is just to prevent minimize confusion. It's less likely you'll think you can use it again later and get pissed at my guard when he tells you you can't. You can't use it to reenter my hypothetical building anyway. Only permanent non-pink badges can without going through the check-id and access list hoo-ha with the security desk.
posted by ctmf at 9:06 AM on January 24, 2007

You might have a visitor that wants to leave for lunch and come back, though. Or a contractor that has to go out to his van a dozen times during the day.
posted by mendel at 9:20 AM on January 24, 2007

And how exactly are you going to do that? Stop and frisk every single person leaving the building?

No, you give them their car keys back only when they return the badge.
posted by kindall at 11:15 AM on January 24, 2007

Ooooh, I temped as a receptionist at a place with these a few years back! I admit to having played a bit with the badges at the time; here's my experience:

Guest badges are stickers that, once removed from their backing, have a time-release of the word EXPIRED in big red block letters; the word fades in and is fully visible in circa 8-12 hours. The backing the badge is put onto is irrelevant as is the location of the badge (in/out of building); the time-release is all in the sticker.
Anyone who was a visitor, even for several weeks, ended up having to get a new badge every day.

Also, all visitors were supposed to sign in and out in a book at reception; this wasn't just for security, it was for taking a head count in case of an alarm/evacuation in the building; they made some serious stuff there. Military something, or chemicals... I don't really know.
posted by Sprout the Vulgarian at 12:13 PM on January 24, 2007

And how exactly are you going to do that? Stop and frisk every single person leaving the building?

No, you give them their car keys back only when they return the badge.

"The Washington area, where 13 percent of workers get to their jobs by bus or rail, ranks behind only New York and San Francisco in use of mass transit."

Uh-huh.
posted by phearlez at 12:40 PM on January 24, 2007

Here is the best explanation I could find. TimeBadge and self-expiring badge are the search terms I used.

To the objectors: It's quite rude to confiscate a visitor's (prospective client's) car keys or driver's license on entry to the building. It's not rude to give them a badge that automatically times out.

There'd be no way of truly preventing someone escaping the building with their badge unless every fire exit (required by code) were guarded. That's pretty expensive - these badges are cheaper. Seems like this is a use of technology to solve a problem. What's so hard to understand about that?
posted by ikkyu2 at 3:38 PM on January 24, 2007

Ya, like I'm handing my keys to a rent-a-cop. Oh look, the key to the 76 Pacer I sold ten years ago isn't something I ever need back.
posted by Mitheral at 6:03 PM on January 24, 2007

You might have a visitor that wants to leave for lunch and come back, though. Or a contractor that has to go out to his van a dozen times during the day.

Then my security desk id and access list checker is going to get to know that person by sight, and the process will only take a minute. Hi, pink badge #14, can I see your photo ID? (checks name by #14 on list and on ID) Thanks, go right in. I'm not against guards having common sense and holding the guys badge for a minute or two at the desk and giving it right back. Just against them letting unknown people in with temp badges. The process prevents the contractor from finishing his work at 9:15am, leaving, and giving his still non-auto-expired badge to someone else in the parking lot.

It's not that it's hard to understand - if you like the self-expiring badge thing, that's fine. I just think some simple laminated pink cardstock would work just as well, if the process were sufficiently looked at.
posted by ctmf at 7:15 PM on January 24, 2007

The "I know him on sight and it's busy so I'll let him pass" wetware attack is the vulnerability the expiring badge addresses. Places where there are a pair of Marines at the door probably don't have this problem but companies who have a single minimum wage employee handling all security details may want to help those employees do their job.
posted by Mitheral at 12:24 PM on January 25, 2007

Or even a non-minimum wage person who may be dealing with potential customers. We're a controlled facility at my workplace but we also have customers coming and going. Anything that allows our 'gatekeepers' to exert authority firmly and simultaneously reduce the chance that a legitimate person will be denied entry - and potentially piss them off enough that they consider a different contractor for that 3M job - is a good thing.

Simply saying you're going to confiscate everyone's ID that you hand a badge to is a great example of the absolute solution that works perfectly (well, not really given the above non-driver/fake key problem, but we'll stipulate for the sake of argument) but completely ignores the human dynamics that are at play in real human society.
posted by phearlez at 9:31 AM on January 26, 2007

UPDATE: I had to get a temporary badge today (darn busy weekend seeming long), and I saw the backs of the white stickers' sheets. They are definitely the TIMEbadge that edgeways mentioned. If I could mark your answer "Best" twice, I would do it four times!
posted by Xoder at 9:04 AM on January 29, 2007