It’s not uncommon for us to delve into the fundamental elements of printing in our Between the Pages blog. We’ve explored options for binding, and pro-tips on choosing the right paper stock, but never before have we touched on the basics of ink. Four primary colours - cyan, magenta, yellow and black - at the core of what is commonly referred to as ‘process’ printing. Dominated by two heavy-hitting production engines - offset and digital - we explore the differences in their inks, method of application and important environmental credentials for each.
INKS FOR OFFSET PRINTING
Offset printing inks are specially compounded to withstand both dilution and reaction with water and the press fountain solution used in the production process. Their key functions are to retain colour and coverage on various paper substrates, and most importantly, dry within a relatively short time frame. Offset inks are made up of three ingredients:
The liquid carrier that holds the pigment particles
Modifiers - Additive ingredients to control drying, smell and resistance to fading.
The most commonly used ink is black, followed by the other three ‘process’ colours - cyan, magenta and yellow (CMYK). It is these four pigments, used in synergy, that create the kaleidoscope of colour we see in printed magazines, brochures and catalogues.
The one exception to the CMYK rule is choosing a PMS colour or a pure ink mix. PMS - short for Pantone Matching System, are hundreds of colour options produced outside of the CMYK gamut. Instead, they are mixed from a combination of ten ink pigments - black, white, rubine red, rhodamine red, warm red, reflex blue, process blue, green, purple and yellow.
INKS FOR DIGITAL PRINTING
The other common production engine in ‘process’ printing is digital - often referred to as laser printing. Using toner - a fine polyester-based powder instead of ink, these machines rely on opposing static charges combined with fusion heat to produce a printed sheet. An electrostatic template of your image is transferred onto a rotating metal drum with an electric charge. The toner attaches itself to the charged sections of the drum, transferring your image onto the oppositely charged sheets of paper and fusing it into place with heat.
Hybrid machines, however - like Printcraft’s Indigo Press, although still classified as digital print technology, uses a liquid ink instead of a powdered toner. Manufacturer Hewlett Packard calls this Electroink, an electrocharged pigment inside a viscous paste, similar to that used in offset printing. The ink, however, is still loaded into the press via a sealed cartridge, then diluted with oil to form a fluid mix of colourant ready for printing.
Although digital printing is predominantly produced from CMYK only inks, machines like the Indigo press do allow for special mix PMS and ‘bump’ colours. Because of its liquid consistency, you will also find gloss levels slightly flatter, making them more consistent with traditional offset printing.
Pro tip - Colours from digital and laser technology are usually more vibrant than those produced on traditional offset machines. When run by skilled operators, digital equipment is more flexible, and can generally produce a wider gamut of colours. If your campaign has multiple print components check on the technology with your print provider. If it spans across both offset and digital equipment we recommend printing the offset components first. It will be far easier to ensure colour consistency in this way.
ARE THE INKS ENVIRONMENTALLY FRIENDLY?
For many customers, the type of ink and method of printing is inconsequential. For those conscious of the environment, however, the two processes and their consumables should be considered.
Most offset printers today have shifted from using petroleum-based ink to a more reliable and eco-friendly soy-based product. Although not 100% biodegradable, it is four times better than petroleum-based inks and more easily removed in the de-inking process used for recycling.
Toner, although not considered toxic, is not biodegradable, often containing iron oxide, styrene and acrylate - none of which can be broken down. Digital printing also comes under fire from the millions of cartridges that still end up in landfill each year. Unfortunately, we do not have the option to purchase digital printing ink or toner in the same 10kg drums as we do for offset inks.
If you would like more information about the types of ink we use, how they represent on different paper stocks, or their environmental credentials don’t hesitate to reach out to one of our friendly, experienced sales team.