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Signing the back of your credit card


ek-hornbeck

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Occasionally, I get a new credit card and have to put my signature on the back. And when I do this, sometimes I discover a week later that the ink I used to sign hasn't really bonded to the credit card's signature area on the back of the card, becoming smeared over time as the card is handled. So I decided to make a little experiment to determine which pens and ink were best for signing — not for signing a credit-card slip, but for signing the actual credit card itself. What I want is an ink that will permanently bond to the credit card, and not smear or be otherwise eradicable.

 

I took two old, expired cards and tried out 7 pen/ink combinations, making a line with each of my pens:

  1. Sharpie Pro
  2. Zebra Onamae Mackee
  3. Sakura Pigma 0.5mm
  4. Sakura Pigma PN
  5. Uniball Signo DX gel pen
  6. Montblanc Permanent Blue (in a Pelikan pen)
  7. Generic Bic Stic ballpoint pen

The Sharpie Pro and Zebra pens are alcohol-based permanent markers given high marks in an article on JetPen's web site. (The Sharpie Pro is a fine-point marker marketed as a particularly dark and permanent variant on a basic Sharpie; it is known to smell a little more than a basic Sharpie, something about which I don't care at all.) Alcohol-based markers tend to do better on plastic surfaces, compared to water-based inks designed specifically for paper.

 

The Pigma pens are water-based nanopigment inks developed specifically for museum archival purposes.

 

The Uniball Signa DX is a gel pen whose ink is well regarded for its archival properties. Gel inks are known to be stable and essentially impossible to remove. (From paper, anyway. The back of a credit card is a very different kind of surface.)

 

Montblanc's Permanent Blue is a nanopigment ink and is one of the rare inks certified for ISO 14145-2 archival properties. It is a water-based ink, like all fountain-pen inks.

 

The Bic Stic is a generic ballpoint pen, for comparison — it's roughly what you'd get if you grabbed some random ballpoint pen and signed with that. Like any other ballpoint, its ink is a dye-based (not pigment-based) ink in an oil (not water) base. Ballpoint-pen ink is known to be vulnerable to attacks by organic solvents such as acetone.

 

All of these inks, except for the generic ballpoint ink, have some claim to fame for being permanent, archival, difficult to wash out or fade, etc. However, as noted above, inks are usually designed to work on paper, which has cellulose fibers to which it can bond; the back of a credit card is a smooth, non-porous plastic surface, so things may work out very differently in that context.

 

I wrote a short line with each of my pens. I wrote these lines on the rectangular “signature block” area on the back of the credit card, which is treated with some coating that is clearly designed to be better for writing than the slick surface of the plastic used for the card itself. After writing the test marks, I left the card alone for a week to let all the inks dry.

 

Then I tried to smear them by rubbing my thumb, hard, over the surface. The results were quite clear, even if the inked lines were not. All the water-based inks failed to bond to the plastic: I was able to smear and rub out the lines made with the Sakura Pigma pens, the Uniball gel pen, and the Montblanc Permanent Blue. All I needed to do was rub my thumb over the lines with some pressure, to make the lines almost completely disappear.

 

The two alcohol-based inks, however, hung in there: the Sharpie Pro and the Zebra Onamae Mackee did fine, although the Sharpie Pro did a little better.

 

The ballpoint-pen ink also hung in there. I suspect that the material used for the little signature area on the back of the card was likely designed to work well for standard ballpoint ink; it's what most people use day-to-day. (In particular, it is higher-friction than the actual card plastic, so it's easier for the ball of the ballpoint pen to rotate and lay down ink as the pen tip travels across the signature-block area.)

 

Next, I soaked a microfiber cloth in isopropyl alcohol and used it to scrub the test lines with some pressure. This finished the job on the water-based marks: even the ghostly remaining images were wiped clean. The Zebra Onamae Mackee greyed out slightly under the alcohol attack, while the Sharpie Pro didn't alter at all. The ballpoint-ink also faded a little bit under the alcohol attack.

 

Finally, I soaked a paper towel in an acetone-based nail-polish remover and scrubbed the back of the cards. That was the end of the experiment, as the acetone completely dissolved the material used to make the signature block on the back of the card. All the ink was removed when its underlying substrate liquified, of course. The acetone didn't seem to hurt the actual plastic of the card, just the white stuff used to make the signature-block surface that is on top of the underlying plastic.

 

So the answer is clear. The Sharpie Pro is the way to sign your credit card. The Zebra Onama Mackee is pretty good, too — and it writes a finer line than the Sharpie Pro, which is nice when you need to write small in the little signature-block area on the back of a credit card. And a ballpoint pen isn't too bad… but I must admit that I remain distrustful of ballpoint ink. An organic solvent less aggressive than acetone might lift it right off the card. But I haven't verified this in purpose. (If anyone reading this little note does an experiment to settle this, I hope you will post your results to this thread.)

 

I hope this trivial little experiment is of utility to people.

 

EKH

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CCs these days have a chip that interfaces with a reader which requires a PIN #.  No one's looked at my cards for a signature in 20 years. Not something I worry about.

Add lightness and simplicate.

 

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Thank you, @ek-hornbeck for this report on your experiments.  I found it to be an interesting read and I appreciate your methodological approach.  I'm sorry I don't have anything substantive to add, but I wanted to acknowledge your effort and contribution to the community.

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thank you for this post. 

 

:)

 

 

Just give me the Parker 51s and nobody needs to get hurt.

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No one's looked at my cards for a signature in 20 years. Not something I worry about.

 

Our post office does.

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1 hour ago, Ron Z said:

Our post office does.

 

 

Ours doesn't 😀  Different country.

Add lightness and simplicate.

 

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4 hours ago, Dione said:

black ballpoint pen as required by the card issuer

Curious: is this a particular card issuer, or all of them? I assume this requirement is buried in the pages and pages of online T&Cs, because none of my cards contain that requirement on the physical card. In fact, if I read correctly, I don't really have to sign it. 

 

52 minutes ago, Karmachanic said:

Ours doesn't 😀  Different country.

 

The two I frequent don't either, same country as Ron Z. Although I suppose they might if my transaction were large enough to require signing, I've never tried that. 

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5 hours ago, Karmachanic said:

CCs these days have a chip that interfaces with a reader which requires a PIN #.

Where I live, credit cards don't require pins. If your charge is below a certain amount (seems to vary by store or something, I don't have that figured out) it just goes through. Higher than that requires a signature, at which point the store might also want to look at the card (hasn't happened to me in dog's years, but it could). 

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In the US here. I haven't signed the back of a credit card in years - which is not to say I'm not supposed to, there's a space for my signature. Hasn't been an issue.

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Very interesting and well done systematic approach, ek-hornbeck. Thank you for that!

 

Starting with the very first card I ever received, I never even thought about using something else than my fountain pen with normal, non-waterproof ink for the signature. Never ever had there been a problem, although hotels and some shops had compared the card signature with the one I did live on a bill - often to their surprise, when I refused to use the ballpoint pen they offered to me.

 

So, yes, there is a life without ballpoint pen.

 

One life!

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I tried some de Atramentis Document pigment ink on one, let it dry for a while, but it wiped right off with a gentle finger touch, and worse, seemed to make the surface difficult to write on with anything (including a ballpoint space pen).

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On 6/19/2021 at 5:10 PM, brokenclay said:

In the US here. I haven't signed the back of a credit card in years - which is not to say I'm not supposed to, there's a space for my signature. Hasn't been an issue.

About 25 years ago, I worked for a while in a local Jo-Ann Fabrics location.  One time when I was cashiering, a woman came up and hadn't signed her card, and told me "Oh, I never sign them!"  And I pointed out that if someone stole her card, and then signed it, and then signed a receipt, the signatures would MATCH.  (of course this was also back in the days of the manual swipe machines and carbon copy receipts, and before everyone had chip enabled cards -- heck I don't even think there were the electronic signature machines back then...).

As for me?  I signed the back of a card recently (don't remember what offhand) with Noodler's El Lawrence.  I often use Noodler's Kung Te Cheng, but didn't have a pen inked up with it at the time.  So far haven't had a problem with El Lawrence.

But I also just saw a report on the noon news of the rise of fraud and complaints about sites like PayPal and Venmo and how they are not overly helpful when people get scammed.  And have gotten three calls in the past two weeks from spammers claiming to be from Amazon Support (heads up -- Amazon does NOT make calls like that) about a $500 charge and/or a computer bought on my account).  The callback number was NOT the number for Amazon Support, and I looked that up and reported the first two calls to Amazon (the stupid person who made the second call was too stupid or lazy to change the message to have the callback number be the same as what showed up on the caller ID).  But I know better -- none of the numbers OR callback numbers were toll free area codes, and after contacting Amazon directly, I reported the numbers (and the callback numbers as well) on a bunch of sites designed for reporting spammers.

Ruth Morrisson aka inkstainedruth

"It's very nice, but frankly, when I signed that list for a P-51, what I had in mind was a fountain pen."

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  • 2 weeks later...

I use a sharpie and then tape over it with clear tape.  A nice librarian taught me to do that and the tape makes a HUGE DIFFERENCE.

Fountain pens are my preferred COLOR DELIVERY SYSTEM (in part because crayons melt in Las Vegas).

Create a Ghostly Avatar and I'll send you a letter. Check out some Ink comparisons: The Great PPS Comparison 

Don't know where to start?  Look at the Inky Topics O'day.  Then, see inks sorted by color: Blue Purple Brown Red Green Dark Green Orange Black Pinks Yellows Blue-Blacks Grey/Gray UVInks Turquoise/Teal MURKY

 

 

 

 

 

 

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