Matching Colours (Part 2)

November 6, 2012

in Prepress

For Matching Colours Part 2 we’re going to look at the issues with printing a special Pantone colour across a number of paper types.

Last month we were tasked with printing a number of items for a new brand and the example provided some interesting issues for colour matching.


Our client was launching a new part of their business which meant the development of a corporate identity.  The base house colours consisted of a special yellow and a special grey and these were to be reproduce across a range of printed products on silk (coated) and offset (uncoated) papers.

When ink is printed conventional litho the reproduced colour is affected by the surface of the substrate or paper (see our blog links for info on UV-litho and Digital vs Litho).  A coated paper allows the ink to sit higher on the surface and dries from a higher degree of oxidisation than absorption.  If printing onto uncoated paper the ink sinks into the surface of the paper and dries from a higher degree of absorption.  The coated surface reflects light in relatively straight lines giving a bright colour reproduction whereas the uncoated surface reflects light in random directions giving the effect of duller colours (see images below for a simplistic representation).  In short the same colour, printing on five different paper types, will give the effect of five different colours.  Obviously not ideal for consistency across brand identity.

The Pantone Matching System (PMS) has different ink mix descriptions for printing the same colour on coated and uncoated materials and you would have noticed a C or U suffix behind a PMS reference  to designate this e.g PMS200C (for printing onto coated paper) or PMS200U (for printing onto uncoated paper).  If you get an opportunity, do have a look through the Coated and Uncoated Pantone swatches and compare a few colours across the two; it will become obvious how colours differ on different substrates.

Okay, back to the issue;  the main printed item for our client was a corporate folder which printed in PMS116C Yellow and PMS432C Grey, heavy ink coverage of both colours onto a 350gsm silk board.  When we cross-referred these C colours to the respective 116U and 432U colours it became immediately apparent that the business cards, letterheads and compliment slips would never match the folder.

There are two options from this point – we could supply our ink manufacturers with samples of all the papers and ask them to make special ink mixes for each colour that would give the closest reproduction across all the printed material.  The other option, which was the route we decided to go with, had no special ink formulas, no elaborate calculations, no ‘clever’ fixes – we printed the folder in the correct colours and then matched it to the closest yellow and grey references in the Uncoated Pantone swatch.  As it happens the closest special colour matches to PMS116C and PMS432C are PMS108U and PMS433U respectively…who knew?

The result was a suite of corporate material that matched across the whole range and another happy Xcaliba client.  If there’s an issue there is nearly always a solution.


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