Anatomy of Colour - II

Rahul Kumar confabulates with colour consultants and colour scientists to the puzzle of the jargons. Hopefully this will help you in your day-to-day printing

30 Aug 2017 | By Rahul Kumar

Question: Brother, tell me a bit about Pantone.
Owned by measurement systems developer X-Rite since 2007. Pantone provides the most widely used references for specifying colours, which are de facto if not actual standards, used worldwide. Most corporate brand colours are specified as Pantone references. 

Question: Can anyone and everyone use Pantone?
The right to use the Pantone colour sets is licensed to other developers for use in design software as colour swatches, or in printer RIPs and drivers as conversion tables. 

Question: Is that all?
The core to the system are colour reference books, which contain small patches of ‘solid’ colours, with each produced by an individually mixed ink on a specially adapted press. Each colour has a unique reference number. There are 1,867 colours in the current Plus Series. There are also additional sets for metallic and pastel inks.

Question: 1,867 colours! Woah! How are the integrity of these colours maintained?
The core is the formula guide for coated and uncoated papers, that gives ink ‘recipes’ to allow every colour to be mixed as a spot colour from 14 base inks that are licensed by Pantone.

Question: What about spot colours?
This works fine for processes that allow spot colours, but process CMYK and extended gamut sets are more economical for many analogue presses.

Question: Pantone for digital? Is it tenable?
Again, a good question.

Question: Thank you, brother.
The only digital print process that supports specially mixed inks is HP with the Indigo liquid toner presses. 

Question: And what is this thing called Pantone’s Colour Bridge guide?
The Pantone’s Colour Bridge shows all its colours with their nearest equivalent CMYK offset values on coated or non-coated papers.

Question: What about the extended gamut for seven-colour printing like those packaging firms?
This isn’t a standard, but a trend that affects some standards.

Question: Meaning what, you are talking gobbledygook?Answer: CMYK process inks are strictly limited in their colour gamuts, with a lot of colours that they can’t match (oranges, russet browns, bright greens, pure blues, purples, etc). Many Pantone colours fall outside the gamut of standard offset CMYK, although many digital printers have wider gamut CMYK. 

Question: Extended gamut process sets are also available with six or seven colours. This is usually CMYK plus orange, green and violet, but sometimes including red or Reflex Blue. What does digital say about this?
A lot of inkjet photo printers have some or all of these extra colours as standard. 

Question: Say something more. Some more colour stuff.
The makers of the extended gamut ink sets will often describe the coverage of their sets as for example “85% of PMS,” or “90%” etc, where standard CMYK matches about 50 to 60%. This doesn’t say precisely which colours can or can’t be matched, but it’s a broadly useful indicator. 

Question: How are colour separations managed?Answer: Usually the RIP or printer driver suppliers will look after the colour separations from RGB input files. Some printer companies have created their own swatch books of key Pantone values that customers can use as reference guides. 

Question: Too tough. Can't all this be simplified?

Question: How?
Last year Pantone simplified matters with the introduction of the Extended Gamut Guide. This shows the results of seven-colour inks (in this case CMYK plus orange, green and violet) with 1,729 solid colours (it gives Pantone numbers and RGB values for the solid colours). It’s based on offset inks on coated papers, but can be used as an approximate guide to the capabilities of other processes with similar colour sets.

Rahul Kumar, PrintWeek India

Thank you Simon Eccles, freelance printing industry journalist and PrintWeek UK for the colour inputs.