Colour reproduction





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Colour reproduction
The four colour process

Over the last few years, numerous organisations and associations have worked on normalisation (standardisation) of process colours with the aim of defining, in a predictable manner, the characteristics of a print job.
In other words, this normalisation should allow the printer to certify that the reproduction of colours corresponds in all respects to the client’s contractual proof and also therefore to allow the person placing the order to be certain of obtaining the same result whatever the printer.

2 standards now apply to the 4 colour process:

ISO 2846: Graphic technology - Colour and transparency of printing ink sets for four-colour printing.
This standard defines the test method and the colorimetric and transparency tolerances of a four colour printing process on laboratory prints (solid prints). The different chapters of this standard correspond to the different printing processes (sheet fed offset, flexo, etc.).
The printing is carried out on standardised paper and the values are measured by means of a spectrophotometer. The standard details the tolerances as a function of the measurement conditions used (geometry of the spectrophotocolorimeter, illuminant, angle of observation, etc.).

ISO 12647: Graphic Technology: Process control for the production of half-tone colour separations, proof and production prints.
This standard defines the printing parameters on offset presses.
As previously, the different chapters correspond to the different printing processes.
Values of solid print densities and dot gain values according to the ISO 12647-2 Standard (1996)

Gloss coated paper
Colour
Density
Tolerance
Dot gain 80%
Tolerance
Dot Gain 40%
Tolerance
cyan
1,55
± 0.10
12%
± 2%
16%
± 3%
magenta
1,50
± 0.10
12%
± 2%
16%
± 3%
yellow
1,45
± 0.15
12%
± 2%
16%
± 3%
black
1,85
± 0.15
13%
± 2%
19%
± 4%
Matt coated paper
Colour
Density
Tolerance
Dot gain 80%
Tolerance
Dot Gain 40%
Tolerance
cyan
1,45
± 0.10
12%
± 3%
16%
± 3%
magenta
1,40
± 0.10
12%
± 3%
16%
± 3%
yellow
1,25
± 0.15
12%
± 3%
16%
± 3%
black
1,25
± 0.15
13%
± 3%
19%
± 4%
Non coated paper
Colour
Density
Tolerance
Dot gain 80%
Tolerance
Dot Gain 40%
Tolerance
cyan
1,00
± 0.10
14%
± 2%
22%
± 5%
magenta
0,95
± 0.10
14%
± 2%
22%
± 5%
yellow
0,95
± 0.10
14%
± 2%
22%
± 5%
black
1,25
± 0.10
14%
± 2%
25%
± 5%
 
Did you know?
The inks manufacturer undertakes to provide a certificate of compliance with the ISO 2846 Standard, which allows the printer to dispose of a set of “standardised” process colours that meet the requirements of the ISO 12647 Standard.
It should however be noted that compliance with the ISO 12647 Standard depends on numerous parameters such as the press, the blankets or the substrates, which all have a considerable influence on the print result.
It is for this reason that the printer is exclusively responsible for compliance with the ISO 12647 Standard.
Pantone® Hexachrome® six colour process

Hexachrome printing (launched by Pantone® in 1994) is a means of extending the colorimetric space exploitable in four colour printing.
This process enables prints to be optimised thanks to more accurate reproduction.

Hexachrome process = 4 basic colours (of slightly modified colorimetry compared to the Eurostandard) + Orange + Green

Yellow part = colorimetric space covered by the 4 colour process

Violet part = colorimetric space covered by the 6 colour process

Whereas the 4 colour process represents 14% of the visual space, the Hexachrome 6 colour process enables a 47% increase compared to the 4 colour process and therefore 20% of the visual space to be covered.
NB: Hexachrome® colour bases have virtually zero light fastness (> see “Fastnesses of inks”). It is recommended to assess the final use of the printed material and, if necessary, to use light fast hexachrome colours (different shades).
Please consult us for further information.

Pantone® systems


The most widely known Pantone® system, known as PMS (Pantone Matching System®) was developped in 1963.

It comes in the form of a colour chart containing 1000 colour shades made up from 13 bases, a neutral mixing black and a transparent lacquer.

In September 2007, the Pantone® Company launched a new system on the market known as the Pantone Goe™ System.
Containing 10 bases and a “transparent lacquer”, it comes with a colour chart containing more than 2000 colours.

Unlike the PMS system, where certain colours cannot be overprinted with acrylic or UV varnishes, the pigments selected in the Pantone® Goe™ system offer the possibility of varnishing all of the colours in the colour chart.
Did you know?
These colour charts should not be considered as colorimetric standards but as guides containing formulas that facilitate obtaining the required colour shade.
Every year the Brancher Company submits its base inks referenced by Pantone® for re-certification purposes.
 





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