When a print shop asks for CMYK, we are not being obscure. We are naming the four process inks that build full-colour images on paper and many large-format substrates: Cyan, Magenta, Yellow and Key (black). Those four “plates” overprint in tiny dots. Your eye mixes them into photographs, logos and solid colours. That system is called process colour.
Why “K” is black, not B
Black is called Key because the black plate is historically the key plate that carries detail and contrast. Mixing cyan, magenta and yellow alone makes a muddy dark — not a clean black — so presses add a dedicated black ink for text, shadows and sharp edges. On our site, the black desk is the “heritage” plate for the same reason: it holds the detail that registers everything else.
Digital presses still speak CMYK
“Digital printing” does not mean the machine prints in RGB like a phone screen. Most production digital presses and many wide-format printers still lay down CMYK toner or ink (sometimes with extra gamut colours). The workflow converts your artwork into separations the engine can fire. If you design only in RGB and never convert or proof for print, bright screen blues and greens can shift when they hit paper.
RGB for screens, CMYK for print
- RGB (red, green, blue) — light on screens: phones, laptops, TVs
- CMYK — ink or toner on substrates: paper, vinyl, many boards
- Same logo can look punchier on a monitor than on a coated flyer — that is gamut, not a broken press
We still accept RGB files every day; part of pre-press is converting and checking them for the device that will print. Sending a print-ready PDF in CMYK with fonts embedded and bleed included simply removes surprises.
Registration: why the plates must line up
Registration means each colour lands in the right place relative to the others. Mis-registration shows as coloured fringes or soft type. Traditional offset used physical plates; digital engines register electronically, but the idea is the same. The “registering plates” moment on our home page is a nod to that craft — four colours, one image when they lock.
Practical takeaway for Pretoria jobs
Design on screen in RGB if you must, but finish for print with CMYK in mind. Prefer PDF for press work, keep important colour in a gamut that ink can hit, and talk to the shop before a huge run. At Plan Photo Repro in Maroelana we have been matching colour to substrate since long before digital — the inks changed; the need for clear process colour did not.