I have created a logo where the brand color is a cool grey. The CMYK values for the grey are C10 M0 Y0 K68. I do realise that the grey is going to look different depending on the printer. My client printed the logo on 2 of their office printers and got different results. Would it be better to convert the grey to all 4 colors (in this case C64 M49 Y45 K15) in order to get the most consistent grey when printed? I have the Pantone colour match which I will give to the client. But I was just wondering if converting to 4-color CMYK grey would be any better than a 2-color CMYK grey?
If you really need consistent colors, you should print a letterhead with spot inks on an offset print shop. Let's say you print 1000 letter-sized paper sheets, and you just print the text inside it. Offset inks resist the heat of laser printers.
If your client still wants to use any color printer, they must be calibrated using a colorimeter like https://www.xrite.com/categories/calibration-profiling/i1studio
There is NO other way.
Well, you can tweak your logo for every printer + for every application, and combination of them, and you will have like 10 versions where everyone should know where they are going to send and print to use the proper tweaked version... Not a good option.
Tweaking a color IS an option if you are doing it on your own printer and need a cheap fix to send some tests to your client. But that is the only case you should do that.
(You already have the answer in comments, but I'm taking the liberty of transforming them into a proper answer. I don't agree that this question can't be answered.)
The short answer is: no, converting C10 M0 Y0 K68 to C64 M49 Y45 K15 wouldn't give a more consistent result on two random office printers.
As you mentioned yourself, a CMYK color will look different when printed on different devices. Just providing CMYK values and no color profile leaves room for some variation.
But more importantly, most office printers won't accept CMYK values directly. It might assume some CMYK profile, convert to its own RGB profile and then convert to CMYK again when printing. The misinterpretation that happens here would happen with any set of CMYK values.
You might get more consistent results if you convert your CMYK colors (using which profile?) to sRGB, which all printers should be able to understand. But if the two office printers aren't properly calibrated they will never be able to produce consistent colors.
Don't let the client lure you into thinking this is somehow a problem with your file. Perhaps ask them to print some other image or graphics on these two printers and compare the results. My guess is that these will also look different.
As above, if you print in CMYK on different printers, or in a commercial print shop, the logos will print differently. If you want consistency across all printing platforms, you print in a PMS Gray of your choosing. If you really want a custom gray color as a PMS color, get in touch with your vendor who will produce drawdowns for you to approve. Once you approve, they'll mix and print to that specification. The ink can be kept in the name of your client in that specific formula. If you want to imprint on your office printer, ie body text for a letter, have your print vendor print what we call shells - the basically have the logo, return address, phone number, etc, that remains consistent across the letterheads. You can print 1,000, 5,000, or 10,000 shells at a time, trimmed and save in the closet at your clients office. Then they just feed that into the in-house printer with the body copy they want. You can do the same with envelopes, memo pads, business cards, etc. For other uses such as promotional work, you shouldn't be using CMYK for logos since again that color will be determined by the overall print run. The client's logo should always be consistent. Again, you can go back to that custom gray ink that you now have on hand with a consistent formula. Is this a 100% guarantee? No since substrates and conditions can change. But it won't be as badly matched as trying to do a CMYK gray across all platforms, substrates and machines.