We often learn that RGB stands for Red, Green, and Blue, while CMYK represents Cyan, Magenta, Yellow, and Black. However, it’s crucial to clarify that the “K” in CMYK doesn’t stand for Black; instead, it stands for Key.
So, what exactly is the Key (Key plate) in CMYK?
According to Wikipedia,
In printing, a key plate is a plate which prints the detail in an image.
When printing colour images by combining multiple colours of inks, the coloured inks usually do not contain much image detail. The key plate, which is usually impressed using black ink, provides the lines and/or contrast of the image.
Wikipedia
In essence, the Key plate is the plate that provides the maximum detail in the image. During printing, the Cyan, Magenta, and Yellow plates are properly aligned with this key plate.
While in modern printing, the key plate is usually inked with black colour, historically, other colours like Brown and Blue were also used. Over time, Black became the predominant choice for key plates. As Black ink became standard for the key plate, the term “K” in CMYK came to be associated with Black. However, you can say this association is not accurate.
It’s important to note that companies like Adobe utilise their own colour profiles. Therefore, in desktop applications using the CMYK colour mode, “K” typically represents Black. However in the printing domain, CMYK stands for Cyan, Magenta, Yellow, and… Key, of course!
let’s talk about printing plates. They’re like thin, flat metal sheets, usually made of Aluminum. They look something like this.
While (offset) printing, an image is transferred onto these printing plates, one for each colour (CMYK). These plates are then dampened and inked. Next, the inked image is transferred from the plates to a rubber blanket and then to the printing surface. Finally, the printed materials are dried, resulting in the finished product.
You can also watch the video below to see how offset printing actually works and how Key plates are placed to produce accurate colour results.
Frequently Asked Questions
What does the “K” stand for in CMYK?
The “K” in CMYK stands for Key, not Black as commonly believed.
What Are Printing Plates?
Printing plates are thin, flat sheets of metal commonly made from aluminum. They are used in printing products like business cards, catalogs, and brochures.
Source: Print Runner
Why is Black ink typically used for the Key plate?
Black ink is often used for the Key plate because it provides sharpness and depth to the printed image.
Have other colours been used for the Key plate historically?
Yes, historically, colours like Brown and Blue were used for the Key plate, but Black became the standard choice over time.
Does the “K” always represent Black in CMYK colour mode?
While in desktop applications it usually represents Black, in the printing domain, “K” stands for Key, representing the Key plate’s importance in the printing process.
