Sometimes, at Kmart, all I have is a red pen for people to write checks with or sign their credit card slips.
This has only happened once or twice, but someone told me that signing in red ink means that it’s “Invalid”. One woman insisted I get another pen, as she didn’t like red, as it looked bad.
Yet, for all the checks and credit slips we’ve done in red, there’s never been a problem.
What’s the “straight dope?”
I can give you the empirical answer that I’ve signed many a check with a red pen and every single one of them has been cashed.
Haj
I have never heard of any such restrictions, and find it difficult to imagine where that story originated - unless:
I remember forms having instructions to “complete using blue or black ink” - I suspect that was to get a legible photocopy - red, green, whatever, would be low-contrast.
Of course, a bank may specify that checks are to be written in blue or black - whether the Comptroller of the Currency would object, I don’t know.
The Sacramento CA County Sheriff’s Dept. recommends red ink for checks:
shades of my correction center days - I had a significant # of them refuse to use a red pen because of some supersticion (I was never real clear on what the deal was, something involving death either of the writer or a loved one)
The only objection I could think of is the issue of contrast - dark blue/black ink provides for excellent contrast, ease of processing.
In my days of working at a bank it was my understanding that not using red ink was an issue with the microfiche machines of the day.
At the end of the day, all checks were sent through a machine that photographed them as a permanent record of the days receipts. The microfiche was photographed in black and white and red ink showed up light or not at all.
This is likely not an issue with today’s achival processes.
I think this UL may be based on the fact that red did not come up well or at all on some photocopiers and some people used that gimmick to obstruct processing, not only of checks but other documents.
Only time I’ve seen such a code in action wasn’t for checks, but for time cards. Bell Labs time cards to be specific, many years ago. As little sense as it made for salaried employees, we had to fill out one twice a month (putting the same thing on it practically every time). One time I wound up with a bit of a hassle with payroll because I filled it out in red. It turned out that time cards in red ink were for adjustments to previously filled out cards, and I confused their data entry procedures no end. I shudder to think what would have happened if I had filled it out in green.
Slightly off-topic, but I once endorsed a cheque in orange hi-lighter. It went through. 
Slightly off-topic, but I once endorsed a cheque in orange hi-lighter. It went through.
Slightly off-topic, but I once endorsed a cheque in orange hi-lighter. It went through.
You can chisel a check on granite and sign it in blood, if you want, as far as legality goes. Other considerations, such as copying, may be applicable, but no legal considerations.
I have only heard of the “black ink only” rule applied to transactions like contracts – a house closing in particular. Even dark blue ink, I was told, was not permissible.
Slight hijack:
A funny thing about a lot of what has been posted that implies that red does not reproduce well. Quite the opposite, in fact. Most orthochromatic reproduction processes interpret pure red as black (and pure blue as white). The problem, I believe, is not the COLOR, per se, of these colored inks, but their VALUE (darkness vs. lightness).
You obviously weren’t trying to cash a cheque in the Shire:
Anyone knows that if you don’t want things to show up when photocopying, you use blue ink, not red. Specifically “non-repro” blue, a specific light blue shade that copiers cannot read.
What you don’t want to use to write a check is one of those “erasable ink” pens. A friend who worked at a bank refused to even own one on the off chance that he might accidentally use it to write a check. Of course, this was years ago, and the security printing on the face of the check may have improved since then.
In one of my mom’s teacher ed classes it recommended not using red ink to write notes to students, because Koreans use red ink for writing the names of the dead, and for some, it’s a problem to see their child’s or their own name written in red ink. Since you can’t tell whose parents are Korean, it’s best to follow the same policy for everyone. (I Googled a cite, here, but it’s not where I originally read it. http://korea.insights.co.kr/english/question/4/007.html )
I wouldn’t think writing checks in red ink would be connected to that…or would it?
Corr
Actually, I’ve never heard the color of the ink to matter in the validity of contracts.
Where it may matter is in real estate documents that get recorded in the county clerks’ offices like deeds and mortgages. In several of the counties in New York, the county clerks will require a particular color ink for a document to be recorded. Some require black ink, because sometimes blue ink may have problems being reproduced. Others require blue ink, so the clerk can determine that the document being filed is an original and not a photocopy. For instance, Suffolk County requires one, and Westchester County requires the other, though I can’t recall which is which off the top of my head. Either color will work in New York City, however. As a Real Estate lawyer, the important thing to do is to check what the recording requirements are before you get the documents signed.
Hijack
Just on Friday a coworker of mine was discussing how worn her credit card was. I looked at it and on the back not only had the signature rubbed off but also the white part on which you signed. This exposed the VOID VOID VOID beneath and would you believe people STILL took the credit card. I told her to get call her bank and have them reissue a good credit card.
OH yeah BTW a quick google search confirms the reason the banks don’t LIKE red ink is that it fails to show on microfische. But even so ANY ink is valid. Also even a check in Pencil is valid. It is just dangerous as the amount could be altered.