April 22, 2010 7:19 AM   Subscribe

What kinds of things have words written on them in ultraviolet ink?

My curiosity was piqued by a comment from this thread that said,

You'd be surprised how many things around you have secret printing in UV ink.

I was surprised, indeed. But, without a UV flashlight, I still don't know what has writing on it. Spy manuals? Manholes? Hatch doors? Is this really as common as implied?

Has anyone found items with secret UV writings? Are they printed on, or written by hand? Is it to keep information away from the average Joe?
posted by amicamentis to Technology (10 answers total) 3 users marked this as a favorite
I just read (somewhere?) that US currency has missing spots when viewed under UV.

Or was it IR?

Never mind, possibly.
posted by gjc at 7:23 AM on April 22, 2010

American Express cards have "AMEX" written in large type on the front.
posted by Gridlock Joe at 7:40 AM on April 22, 2010

Most currency does:

Most passports do, too.

(Not really surprising or "everyday" items though.)
posted by richb at 7:45 AM on April 22, 2010

"For the last two years I've been stamping UV skulls on the Queen's face on all the money that I get out of the ATM. There's now thousands of pounds worth floating around the UK economy, visible only to bees and humans with a blacklight. Given the events in the world's economy over the last couple of years, it seems all the more (im)pertinent."
posted by richb at 7:47 AM on April 22, 2010 [1 favorite]

Police tag laptops and other electronics in UV ink. If they turn up stolen, the police can return them to their owners. I had this done to my laptop, phone and ipod in nyc.
posted by milestogo at 7:47 AM on April 22, 2010

People. (OK, not a word, but still.)
posted by The corpse in the library at 7:49 AM on April 22, 2010

Credit cards generally have UV printing.

US paper money ($10 or larger) have a plastic stripe running the short way across them. Each kind has the stripe in a different place, and the stripes glow in different colors.

That's because counterfeiters used to take $1 bills and clean the ink off the paper, and then reprint them as $100's. Now they can't do that.
posted by Chocolate Pickle at 9:49 AM on April 22, 2010

I got ahold of a UV pen and light a few months ago and started defacing US currency whenever I could. Every tenth dollar or so already had something written on it.
posted by nomad at 9:53 AM on April 22, 2010

(I just wanted to point out that you can buy flashlights to check this out for less than $10 from Amazon. If I met that guy in the other thread who was giving away $10 a day, this is what I would tell him I was spending the money on. A flashlight to check out what stuff had UV-visible ink on it. Alas, for now, I live in a hotel room, and I really don't want that kind of lighting in here. There are some UV-visible things we really don't need to see.)
posted by whatzit at 9:55 AM on April 22, 2010

Some laundries write customer numbers on clothing.
posted by djb at 9:58 AM on April 22, 2010

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