Colours of printer ink

Colour is where the world of creativity and the world of science intersect, at least for most of us. In primary school we are introduced to colour combinations - mix red and blue, and you get purple. Later we learned that you mix red, blue and yellow paint and you get black - but mix red, blue and yellow light, and you get white. It’s a kind of magic.

It’s the magic that makes printers possible. If we needed a thousand cartridges to match the thousand (conservative estimate) colours of nature, printers would be impossible.

In this blog we will attempt to address as many of the common colour questions as we can.

Table of contents:

• What are the 4 colours in the printer cartridge? 
• What are 6 colour, 5 colour and 3 colour inkjet printers?
• How is coloured ink made? 
• What colour uses the most ink?
• What colour uses the least ink?
• Why does my printer use colour ink when printing black?
• What colour is k on a printer?
• Colour bars printing
• Conclusion

What are the four colours in the printer cartridge?

Typically a printer cartridge has cyan, magenta, yellow, and black, commonly referred to as CMYK. These colours are used in combination to create all the others when printing. Cyan is a shade of blue, magenta is a reddish-purple, yellow is yellow, and black is used for text and to enhance contrast in printed materials.

What are six, five and three colour inkjet printers?

A 6-colour inkjet, or hexachrome, printer, uses six ink cartridges to produce a wider range of colours and enhanced colour accuracy compared to traditional 4-colour printers. In addition to CMYK, there are cartridges for light cyan (also called light blue) and light magenta (also known as light pink).

The inclusion of light cyan and light magenta inks allows the printer to reproduce more subtle shades and gradients, particularly in areas such as skin tones, pastels, and gradients, making it great for photographs. 

A 5-colour, or penta-chrome, printer, uses light black in addition to the CMYK cartridges. The purpose of the extra black ink is to enhance the depth and richness of black areas in photographs and other images. By having a dedicated black ink specifically formulated for photo printing, the printer can produce more accurate and nuanced black and grayscale tones, resulting in improved shadow details and overall image quality.

It is used by photographers, artists, and designers who require precise control over black and grayscale reproduction. 

A 3-colour, or tri-colour, printer, uses only three ink cartridges to produce printed documents and images. Instead of separate cartridges for each primary colour (cyan, magenta, and yellow), it combines all three into a single cartridge. The cartridge contains three compartments, each filled with a different colour. These are mixed in varying proportions to create the full spectrum. This configuration is often referred to as CMY (cyan, magenta, yellow) or RGB (red, green, blue) colour model.

While tri-color inkjet printers can be cost-effective and simple (they are often the entry-level budget models), they have limitations in terms of colour accuracy and overall print quality. If one colour runs out, the entire cartridge needs to be replaced, which is wasteful.

They are not ideal for professional or colour-critical applications.

How is coloured ink made?

Coloured ink is made by combining dyes or pigments with a liquid carrier, such as water or organic solvents. Dyes, or pigments, are the colourants used in ink formulations. Dyes are soluble molecules that dissolve in the liquid carrier, while pigments are solid particles dispersed in the carrier. The choice of dyes or pigments depends on factors such as colour intensity, stability, lightfastness, and the specific printing application.

If pigments are used, they need to be dispersed evenly in the liquid carrier to prevent settling. This process involves milling or grinding the pigments to break them down into smaller particles and then dispersing them using stabilisers and other additives to maintain suspension. If dyes are used, they are dissolved directly in the liquid carrier.

Then additives are added to improve performance and stability.

The ink mixture is then passed through filters to remove any remaining impurities. This ensures the ink's consistency and prevents clogging of printer nozzles.

What colour uses the most ink?

Black, and by a wide margin. Black is used extensively for text and line art in documents, and is the most frequently used colour.

Among the ‘colours’, cyan (blue) is the most used. Cyan renders shades of blue and green, which are commonly found in images, illustrations, and graphics. The intensity of the colour and the need for smooth transitions within the blue and green spectrum can result in a higher ink usage.

What colour uses the least ink?

Yellow ink is used less frequently compared to other colours, because yellow is often used for specific elements in images, such as highlights, sunlit areas, or specific colour combinations, rather than being used extensively throughout an entire document or image.

Yellow ink is less commonly used in text and line art compared to black ink, and it is often overshadowed by the more prevalent use of cyan and magenta for a broader range of colours. 

Why does my printer use colour ink when printing black?

Some printers combine colours to get black, rather than using the black cartridge. There are a few reasons for this. Pure black can smudge, so combining Cyan, Magenta and Yellow can give a sharper black, richer black, and smoother grayscale.

It can also help with keeping the printhead nozzles clean.

Also, printers may use colour ink mixed with black during the calibration process to ensure accurate colour reproduction. 

Sometimes the settings cause colour combinations to be used rather than black, and changing the settings can revert the printer to using black. If you have concerns, check your user manual, or chat to us at inkshop.ie

What colour is K on a printer?

K always refers to the colour black. To remember, black ends in a K.

Though this is not the reason black is K. K stands for key, and black is often used as the key colour in printing, to define key details, such as text and lines, as well as high contrast elements. By using a separate black, rather than combining colours to get black, you can get better text and line reproduction.

Colour bars printing

Colour bars are a standard test pattern often printed to check and calibrate colour output in printers. The colour bars consist of a series of vertical stripes, each representing a specific colour or grayscale value.

Bars are printed to assess and adjust colour accuracy, saturation, and tone reproduction. By examining the bars, you can identify any colour shifts, inaccuracies, or inconsistencies in the output.

Colour bars typically include the primary colours (cyan, magenta, and yellow) and secondary colours (red, green, and blue). Grayscale bars may also be included to evaluate the printer's ability to reproduce shades of grey accurately.

Printing colour bars regularly and comparing them to reference bars can help ensure your printer remains consistent and accurate.

Conclusion

This blog has been all about colour, which is a huge element of printing. We have tried to answer the most common questions, but it is a huge (and fascinating) subject. If we have not answered your question, get in touch. At inkshop.ie, we love to share our expertise!