#0000FF or Lament of the Print Designer Who Loves Blue
It's known to most of you as "blue", but that designation doesn't nail it. After all, people say that the sky is "blue", or that their pale, bluish business shirt is "blue", or that navy uniforms are "blue". So there's no point in me saying "blue", because you won't get what I really mean. What I mean is #0000FF.
For those of you who don't know, "#0000FF" is a way of expressing colour on a computer, using the RGB colour space. Your computer monitor has pixels with red, green, and blue components (hence, RGB). A pixel can add RGB in equal, maximal amounts to create white, expressed as "#FFFFFF". Without going into too much detail, "FF" is 255 in the hexadecimal number system, used frequently in computer programming. The six digits represent the red, green, and blue attributes respectively. Thus, #FF0000 is pure red, #00FF00 is pure green, #0000FF is pure blue, and "#000000" (the absence of any colour value) is black.
#0000FF is an amazing colour. It's the colour of the classic cobalt blue pigment used by painters and glassmakers. It smacks of polished lapis lazuli. It's rich and deep, simultaneously inflaming and calming the senses. Some statistics show that "blue", broadly, is the favourite colour of a majority of people. Well, #0000FF is my favourite colour, by far.
Unfortunately, there's a problem: You can't print #0000FF... not really.
At this point a lot of people will be scratching their heads in confusion and disbelief: "Huh? Of course you can print blue!" Meanwhile, the designers in the audience will be rolling their eyes: "Oh, here we go, another rant about the CMYK gamut range". You are correct, designers. Go have a coffee while I explain this to the muggles.
Here's the thing: computer monitors add RGB light together - and the aggregate makes white; but when you're printing, you add cyan, magenta, yellow, and black (aka CMYK) inks together - and the aggregate makes black. We call RGB additive (more colours means lighter), whereas process CMYK is subtractive (more colours means darker).
The difficulty with a subtractive colour scheme is that it's inherently more restrictive than just adding different kinds of light together. You can make a colour lighter by simply adding less ink (since the paper is already white - this is called half-toning) but it's never perfect. The reasons for this are complex and have to do with a myriad of factors, including how the inks reflect and absorb various wavelengths of light (and provide the end colour that you observe) and the physical absorption of the inks into the printing medium (usually paper stock).
We call the range of colours that can be produced by any given colour schema its "gamut". Like CMYK, RGB also has a limited gamut compared to "real-life" colour, but for most practical purposes, RGB is capable of producing the vast majority of colours that most humans can see. CMYK... not so much.
The component inks of CMYK have been formulated to be able to cover many, but not all, colours. CMYK is not super great at reproducing #FF0000 red. It's kinda bad at #00FF00 green. But the worst, by far, is the coverage of #0000FF blue. Just take a look at this RGB to CMYK conversion simulation by Wikipedia:
The CMYK spectrum looks different here and there, but blue in particular looks washed out and grey-ish. It's almost like the CMYK colour-space (first conceived of in 1906, and later codified by colour-matching-juggernaut Pantone in the 1950s) was designed by people for whom pure blue and purple represented only fear and sadness.
I disagree: Blue is Joy (or at least Joy's hair).
But wait, there's hope! You see, mixing cyan, magenta, yellow, and black inks isn't the only way to print. We also have what are called spot colours. A spot colour is a premixed ink - in contrast to blending CMYK inks on paper using halftones. The aforementioned company Pantone is best known for the eponymous colour swatches which list various colours that can be pre-mixed by printing companies for precise colour results. Spot colours are important when you're printing large areas of single, flat colours (eg: white text on a solid orange background), because the halftoning dots of CMYK process become a lot more obvious. Spot colours can also be used to make certain colours (like #0000FF) "pop" more, especially when they don't look good in the CMYK gamut range.
Unfortunately, there's another problem:
One of the best inks for producing (something close to) #0000FF is known in the Pantone scheme as Reflex Blue. It's not perfect, but it's saturated and has a vitality that the CMYK equivalent lacks... and many printers HATE it. Naturally, every colour is created using different chemical pigments, and the pigments in Reflex Blue take twice as long to dry as anything out there. Many printers say that it needs to be coated with special treatments because it never fully dries. I can attest from experience that blue projects tend to come back from the printers feeling a bit tacky, and they smear and stain surfaces more readily.
When desktop publishing first started rolling in the 80's and 90's, designers were generally much more aware of the CMYK gamut restrictions. In today's world you're less likely to have print ads, brochures, and promotional folios, and more likely to be focused on in-browser ads, websites, and promotional PDFs. The prominence of digital media means that designers can often design in RGB. It also means the amateurs are more likely to be shocked when their designs fall (chromatically) flat in print.
Professional designers and printers have been dealing with this for a long time and have come up with lots of tricks for working around gamut limitations. But when it comes down to the nitty-gritty, using #0000FF in complex designs is considered a no-no. We could come up with a new, better process scheme by adding additional inks (as some have tried), but it seems unlikely that any new scheme will enter the common usage.
However, as we increasingly move towards a paperless - and thus inkless - world, I'm filled with hope. So I will continue to design with #0000FF blue. It's a beautiful colour, unfairly slighted by the process gamut. Raise a cobalt-blue glass with me and toast: to #0000FF, the best colour of them all.