Define and simplify

The International Standards Organization (ISO) and members of its  Graphic Technology Standardization and Terminology Committee approved a new work item (NWI) and established a working group for 2013 (WG13), charging it with developing a Schema for Certification for packaging supply chain partners. Action took place at the committee’s meeting in Chicago in October 2012.

Work in progress can be seen as a follow-on to ISO-12647-6, the recently released Flexographic Printing Standard. Requirements are being devised to improve workflows, address all types of packaging and include annexes for process control for each of the print disciplines used in our industry: flexography, offset, gravure and digital.

The focus is on providing tools for consumer products companies (CPC) to use when selecting supply chain partners, with expectations of eliminating the current needs for each
printer to comply with each CPC’s custom requirements. As a result of the October meeting, ISO’s policy document, which is now in draft form, will allow for provisions for each CPC to add its requirements for color tolerance or, in the case of Certificate of Analysis (COA) or Certificate of Compliance (COC), specific testing for different packaging.

The goal of the team of packaging experts at ISO is to define and simplify requirements for the global packaging supply chain. The working document created to date is not intended
to be a ‘how to’ documentlike Flexographic Image ReproductionSpecifications and Tolerances (FIRST), butmerely to provide a set of requirements for supply communication. Dubbed ‘What Packaging Needs from Standards Organizations,’ the working document is presented here. This international standard lists requirements and related properties that
shall be used to communicate the standards and processes between CPCs and the printer or supply chain for packaging applications. This document is intended to provide both a reference to discuss the standards needs of the packaging industry and a possible outline of the key features that should be included in an eventual standard.

Scope

This document and any eventual standard are intended to provide a common set of guidelines for the packaging industry to enable consistency in the package print supply chain.

Wherever possible these guidelines and their associated checklists are based on international and national standards and when necessary on industry documentation. The appearance of the printed package is communicated through reference printing conditions that include characterization data and/or International Color Consortium(ICC) profiles per PDFX. These profiles define the relationship between the specified CMYK and CXF spot color data embedded in the PDFX, the final printed product. These profile families represent different combinations of color gamuts that should have common hue angles.

Note: This is not the case in packaging today, where supply chain partners typically request all file formats. A common file format per ISO will simplify the packaging requirements, and PDFX 4 seems to be the ideal tool for communications.

Overview

The fundamental requirements of the package print supply chain are to:
– Define the appearance of the product to be produced;

– Provide defined formats to allow the data representing the designed product to be exchanged among all participants;

– Provide specifications for viewing, measurement and proofing so that all participants will ‘view and measure’ in a common way; and

– Provide the tools to allow common specification, evaluation and testing of
input materials.

Reference Documents

The standards that include the definitions of printing conditions are:
– ISO 15339, Graphic Technology — Printing from Digital Data Across Multiple Technologies — Part 1: Principles and Characterized Reference Printing Conditions;

– ISO 12647-2, Graphic Technology — Process Control for the Production of Halftone Color Separations, Proof and Production Prints — Part 2: Offset Lithographic Processes;

– ISO 12647-6, Graphic Technology — Process Control for the Production of Halftone Color Separations, Proofs and Production Prints — Part 6: Flexographic Printing;

– Committee for Graphic Arts Technologies Standards (CGATS) 21-1, 2 Graphic Technology —Printing from Digital Data Across Multiple Technologies —

Part 2: Reference Characterization Data-2012.

In addition, the applicable specifications for viewing and measurement are:
– ISO 3664, Graphic Technology and Photography – Viewing Conditions.

Note: The interval of changing bulbs should be 2,500 hours or six months of normal usage. Validation for correct lighting and ambient light requirements should be based on measurements. The booth should be press side for visual process control.

– Color Vision Assessment, such as Munsell Farnsworth 100 Hue Testing or Ihishara.

Note: Testing on a quarterly basis to team members involved in color-related decision making provides a good understanding of color discretion and limitations. Test results shared with the collective team provide understanding of each member’s visual color discrimination. People making color decisions should achieve a score of ‘Average Discrimination.’

– http://www.xrite.com/custom_page.aspx?PageID=77

– http://colorvisiontesting.com/ishihara.htm

Instrumentation

Because measuring color is a critical issue in the packaging industry, special attention must be given to the selection, care and identification of the measurement instruments used. Some of the key parameters to be considered are as follows.

Instrumentation calibration:

The primary reference for instrument calibration is the instrument manufacturer’s requirements. ‘Calibration’ is performed when an instrumentis sent back to the original equipment manufacturer’s (OEM’s) factory for adjustments and/or to validate calibration. Daily checks of the instrument/s are performed to insure they meet factory standards/ calibration. Most manufacturers require factory calibrations annually or every other year.

Instrument Identification, 0/45 Devices:

– Device name/serial number

– Calibration date

– Geometry

– Aperture size

– L*a*b* observer viewing angle (D50 2° for Graphic Arts)

– Spectral reflectance per ISO 13655

– Device illuminant defined (M0, M1, M2 M3)

Note: 0/45 or 45/0 devices are for reading flat colors without metallic, strong gloss reflectance or heavy matte coatings.

Instrumentidentification, spherical devices:

– Device name/serial number

– Calibration date

– Geometry (specular included or excluded)

– Aperture size

– L*a*b* observer viewing angle (D50 2° for Graphic Arts)

– Spectral reflectance

– Device illuminant defined (M0, M1, M2 M3)

Note: Spherical devices are for measuring metallic, pearlesences, heavy matte or gloss coatings.

Instrumentidentification, multi-angle devices:

– Device name/serial number

– Calibration date

– Geometry

– Aperture size

– L*a*b* observer viewing angle (D50 2° for Graphic Arts)

– Spectral reflectance

– Device illuminant defined (M0, M1, M2 M3)

Note: Multi-angular devices are for measuring pearlesence, metallic inks or colors with special effects. Multiple angle measurements can be used in different proprietary characterization models.

In-line real-time instruments for color measurements are commonly used in packaging. Including information relating to those instrument types is relevant and pertinent. It is important to clearly separate the following cases:

– Spectral instruments capable of measuring in full accordance with ISO 13655,

– Spectral instruments not fully in agreement with ISO 13655 but providing spectral data with a resolution within specification,

– Non-spectral instruments (normally camera-based).

Web inspection systems are commonly used for real time defect mode detection. There are a multitude of available systems based on different technologies that provide different levels of detection and performance (for example ‘gold standard’ based, full-width 100% inspection, and more.)

Color management

Although reference printing conditions are the key definition of the relationship between device data and printed color, ICC profiles based on these characterization data are a critical element in the packaging workflow. ICC profiles are embedded in PDF/Xfiles to communicate the customer’s expectation to the rest of supply chain.

File formats

All data exchange is based on ISO 15390-7, Graphic Technology — Prepress Digital Data Exchange Using PDF — Part 7: Complete Exchange of Printing Data (PDF/X-4) and Partial
Exchange of Printing Data with External Profile Reference (PDF/X-4p) Using PDF 1.6

Preflight specification

A preflight should be performed by each group involved in passing/transferring files. When preflight fails, communication should take place between the sender and receiverto ensure that the issues are corrected and are not repeated. The preflight specification shall be compliant with the Ghent Workgroup guidelines for PDFX4 — CMYK+Spot (www.gwg.org).

Three usefulreference documents are:

– IDEAlliance Printing Guidelines 12th Edition. Guides and Best Practices, pages 8-10;

– CGATS TR 011, Graphic Technology — Package Development Workflow — Design Concept Through Approved Production File;

– CGATS TR 012, Graphic Technology— Color Reproduction and Process Control for Packaging Printing.

File conversion for printing

Usefulreferences forfile conversion include:

– ISO TS10128. Graphic Technology — Methods of Adjustment of the Color Reproduction of a Printing System to Match a Set of Characterization Data;

– American National Standards Institute (ANSI) CGATS
TR015, Graphic Technology — Methodology for Establishing Printing Aims Based on a Shared Near-Neutral Gray-Scale;

– ISO 15076-1;2010, Image Technology Color Management

— Architecture, Profile Format and Data Structure —

Part 1: Based on ICCv2 and v4

Evaluation of substrates — Process colour inks (measured with 0/45 instrument)

ISO 12647-6 defines CMYK ink hues required to match dataset. ISO 2846 defines ink requirements from laboratory. Hue angles required by most printing today for common appearance are as follows:

Note: The data presented is forflexo. Nonlight-fast inks refer to a standard ink without extended light-fast properties.

Spot color management

The issue of spot-colour definition is still evolving but is critical forthe packaging industry. Two key references in this area are:

Threshold vs.Intensity (tVI) curve — PerISO 12647-6: 2012 defines a generic T VI curve for CMYK and spot colors where color management cannot be used. 12647-6: 2012 Annex B — using spectrophotometry to select the highest point of absorption — ‘bandwidth from solid’).

Testing of using other weighted bandwidths is also being evaluated. 17972-4 VXFX4. This part of ISO 17972 covers the use of CxF when exchanging spot color characterization data. There are many proprietary formats for this communication. This standard will provide a more reliable means for the communication of spot color characterization data. It is usually impractical to print and measure combinations of spot colour inks. Instead, each ink is characterized in conjunction with a print substrate by means of its spectral characteristics and opacity.

– Definition of minimal number of tone values, measurement condition, background, and more.

TVI curves defining spot colorsmust bemeasuredwith spectral density using the correct bandwidth for solid and the same bandwidth forthe tint.

TheCIELAB tolerances forthe solids and spot colors from ISO 12647-6 are shown below. Deviation from these values is for discussion between sender and receiver. A deviation tolerance of +/- 6 h° for spot colors if considering:

– Different print process applications (e.g. offset, digital)

– Usage of a digital characterization for the master (e.g. Pantone Live)

Reporting of press aims (ISO 12647-6 ANNE X C)

The suggested reporting of press aims isdiscussedinISO12647-6AnnexC,which includes the following table.

Design prints

The requirements for designer prints (validation prints)is contained inISO12647- 8,Graphic Technology—Process Control for the Production of Halftone Color Separations, Proof and Production Prints—Part 8: Validation Print Processes Working Directly from Digital Data. This is designed for non-contract proofs, prints, comps providing tools for colors aims and tools for process control, and validation of print.

Proofing

The requirements for digital proofs are defined in ISO 12647-7, Graphic Technology — Process Control for the Production of Halftone Color Separations, Proof and Production Prints — Part 7: Proofing Processes Working Directly from Digital Data Some of the constraints included are:

– Proofs must contain an ISO tint scale for verification.

– Where spot colors are used, the spot color and tints shall be included on the proof for process control.

– Substrates must be same as printing job or per standard.

– Substrates have light fast qualities per standards.

– Control scales tolerances shall be according to standard or per agreement between sender and receiver.

– If spot/special/brand color are used in a particular design, the proof control strip should, when applicable, include the relevant special color solid rendering.

Soft proofing

The current documentation covering soft proofing is being revised and is included in:

– ISO 14861, Graphic Technology — Color Proofing Using Electronic Displays,

– ISO 12646, Graphic Technology — Displays for Color Proofing—Characteristics and Viewing Conditions,

– ISO 3664, Graphic Technology and Photography — Viewing Condition.

Post-processing

Post-processing and finishing are common in packaging applications. Adetailed work was made and is available from The Association of the Graphic Arts (TAGA) Italy and may be used.

COA & COC testing

COA/COC testing is required by CPCs. These tests are designed to insure that all packaging components will maintain the desired design intent and equity by withstanding the rigors of converting operations, transportation and distribution chain to retail. Demands for COA testing and specific requirements are provided by the Consumer Products Companies

Examples of typical testing required could be:
– Brand Color Validation — Print Quality,

– Sutherland Rub Test — American Society for Testing and Materials (ASTM) D5264-98,

– Alcohol Rub,

– Scratch Resistance Test,

– Tape Test — ASTM D3359,

– Light Fastness Testing,

– Slip Angle Test, Burst Test,

– Brand Color Statistical Process Control Reporting — Print Quality,

– Flop index (metallic inks).

This article is reprinted with permission from IDEAlliance SpectrumBulletin 1st Quarter.

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