Supplier Audit

Color is the core of printing and copying work. In today's era of low profit and homogenization in printing, printing companies are increasingly emphasizing the improvement of color management methods for printed products. Among various certification systems, the most highly regarded is GRACoL's G7 certification system. As of now, more than 300 enterprises in mainland China have obtained G7 recognized enterprise qualifications, and the application of printing standardization has also begun to penetrate into small and medium-sized enterprises.

G7 certification refers to the use of G7 calibration methods to calibrate printing systems, ensuring that the performance and tolerances of the paper and ink used meet the requirements of ISO12647-2, and ultimately ensuring that the entire printing process meets the various standards of ISO 12647-2, in order to obtain a certificate of "G7 certification". Verified printing company information will be included in the G7 database for querying, providing printing companies with a wider range of customer trust and sources. According to the existing resources and conditions of the customer, G7 certification can be classified into different levels.

Simply put, G7 determines the CMYK four-color density closest to the ISO standard and generates a plate compensation output curve that meets the gray balance requirements. Throughout the certification process, printing companies can set various parameters for CTP plate making machines and stamping machines, adjust relevant parameters for printing machines, ink, and paper, record these parameters and form a standard, and then maintain and produce equipment according to these parameters in daily production.

The process of obtaining G7 certification for printing enterprises can be roughly divided into three stages: application work, preliminary preparation, and implementation of certification.

1、 Apply for a job

·Certification application

Printing companies can apply for G7 certification from G7 certification bodies in the region through the APTEC website, or directly contact relevant G7 experts and APTEC certification bodies in Hong Kong for application

·P2P QR code and beta application

Before undergoing G7 certification, all enterprises must first apply to APTEC in Hong Kong for a P2P color chart with a QR code attached. Relevant G7 experts must provide customers with APTEC's designated printed test version. It is recommended that G7 approved companies use full sheet test printing sheets, which are split or four open, covering a minimum area of 70% of the printing press.

2、 Preliminary preparation

Although G7 itself is not a true ISO standard, G7 certification requires that the materials, tools, measurement conditions and methods, and observation environment involved in the certification process must meet the requirements of relevant ISO standards. Therefore, before initiating the certification process, printing companies must make corresponding preliminary preparations.

·Ink preparation

G7 certification requires that the ink used must meet the corresponding ISO 2846 standard, which specifies the requirements for four-color printing ink (except for G7 GrayScale grade which does not require it, it is recommended to use standard ink)

·Paper preparation

G7 Colorspace: The paper must have a LAB value color difference of less than or equal to 3 compared to the white paper required by GRACoL 1, SWOP 3, and SWOP 5;

G7 Targeted: The LAB value difference between the paper white and the paper white required by GRACoL 1, SWOP 3, and SWOP 5 should be less than or equal to 5. If the LAB value color difference is greater than 5, the applying company should apply for [paper white compensation adjustment].

·Measurement tools

In the implementation process of G7 certification, professional measuring instruments and software are required to obtain necessary testing data for the certification process.

Spectrophotometers (X-Rite I1Isis, X-Rite I1IO), with calibration reports not expired

Spectrodensitometer (X-Rite 530, 528, etc.), and calibration report not expired

Printing plate measuring instrument (such as X-Rtie ICPlate2 XT, etc.), and calibration report not expired

Measurement software (X-Rite Colorport latest version)

·The instrument and software measurement settings are as follows:

Standard reference body: D50

Observation field of view: 2 °

Density response mode: T

Data format: M0 (UV Included), CGATS format

All color measurements must comply with ISO 13655 standard

·Equipment calibration

Before conducting formal certification testing, printing companies must conduct necessary testing and calibration of CTP and printing equipment, and ensure that the equipment can produce stably and correctly.

CTP calibration: Adjust the CTP focal length and exposure based on the guidelines provided by the CTP manufacturer to ensure accurate reproduction of dot information; Detect the operating status of the plate washing machine, control the pH value of the developing solution within an appropriate range, and ensure the stable and controllable physical and chemical state of the CTP plate making system.

Printing machine calibration: The printing machine (including consumables) should be maintained in a stable state and its relevant physical and chemical parameters should be checked to ensure compliance with requirements. In order to better understand and control the status of the printing machine, necessary printing machine testing should be carried out, including dry density pressure reduction testing, mechanical ghosting, lifting, printing register and other tests. Adjust the printing machine according to the test results (if necessary, ask a printing technician for debugging) until the printing machine is debugged to the optimal working state.

·Observing the environment

G7 certification requires that the viewing conditions of printing machines meet ISO standards. ISO 3664 provides standard observation conditions for the printing industry, which requires that the light source used for printing must meet the following requirements: color temperature of 5000K and color rendering index (CRI) of not less than 90.

3、 Implement certification

After the printing company confirms the necessary preparations for certification, the G7 certification process can be initiated. The entire certification process must have a G7 certification expert on-site to guide the audit. The certification process requires two rounds of testing document printing, which takes at least three hours. The middle hour is used for the production and loading of RIP calibration curves for the CTP system.

·G7 certification knowledge training

G7 experts conducted in-depth training on G7 certification knowledge, interpretation of G7 calibration methods, and use of certification tools for relevant personnel in printing enterprises, enabling printing enterprise employees to understand the entire certification process, key certification links, and preliminarily master G7 calibration methods.

·First round of linear printing

In the original state where CTP does not load any curves, linearly output the G7 certification specific test version, record the layout dot information, in order to better control the plate making process in the future; When printing on this test plate, the printing state must be adjusted to meet the requirements of a stable state. Use a spectrophotometer to find the optimal solid density of the printing machine, and after the printing is stable, select several print samples according to the sampling rules.

·CTP compensation correction

By measuring and extracting specific elements on the sample layout, obtaining necessary information, and using Curve2 software to process the CMYK correction results, new target values are assigned to RIP to complete CTP correction.

·Second round of certification printing

The CTP system loads the calibration curve created above and prints it with the optimal density for the first time. To ensure that the two printing states are as consistent as possible, the two rounds of printing are completed on the same day and on the same machine by the same crew, keeping all settings of the printing machine unchanged. Sample according to the rules in a stable printing state, and submit the sample to the G7 certification expert on site.

·Hong Kong APTEC Institution Audit and Certification

G7 certification experts will make on-site evaluations based on the second round of printing samples. If the on-site evaluation is passed, G7 experts will submit the two extracted samples to the certification agency for final evaluation, which will take about 14 working days. If approved, the printing company will receive a G7 certification certificate and logo issued by the G7 certification body, and the company's information will also be included in the G7 certification database on the website for query.

·Maintenance of G7 Certification System

This is the most important part. The G7 certification is valid for one year, and in order to maintain this certification, one must pass an annual review. So obtaining G7 certification is not the end point. The ultimate goal of G7 certification is to achieve data-driven, standardized, and standardized production, and maintain a long-term, stable, and reproducible printing status.