Printing and packaging quality control, colour management and barcode verification

Colour management

Colour is controlled by reference, not by opinion. Process work is printed to recorded ink densities, and brand colours that must not drift are printed as spot colours mixed to a reference rather than built from process inks. Where a customer supplies a spot reference, a drawdown on the production substrate is made and approved before the run.

The substrate is treated as part of the colour specification. The same ink film on 300 GSM uncoated kraft, on coated art board and on white polyester gives three different results, so proofs are produced on the stock that will be printed. An approved proof on the wrong paper is the most common cause of a rejected delivery in this trade, and it is avoidable.

Retained samples and press records are the mechanism behind reprint consistency. For a repeat order the retained sample from the previous run is placed alongside the sheet on the press and matched under the same viewing conditions.

Proofing process

1. Pre-press check on the supplied file: bleed, trim, overprint, minimum line weight, reversed text size, barcode dimensions, resolution of every standard and compliance mark.
2. Query list issued to the customer where anything is ambiguous, before plates are made.
3. Digital proof on the production substrate, dispatched or handed over for signature.
4. Where required, a plotted die line or a mocked-up sample so the buyer can check fold, punch position and string length physically.
5. Written approval recorded. Plates are made only after approval.
6. First sheet off the press checked against the approved proof and the retained sample before the run continues.

Barcode print quality and verification

A barcode is a printed measurement, not an image. Bar width gain from ink spread, an insufficient quiet zone, low contrast between bars and background, and high-gloss varnish over the symbol are the four faults that cause scan failures at a European or American till. Each is controlled here.

• Symbol dimensions and magnification checked against the specification at pre-press.
• Quiet zones protected in the die line so a punch or trim cannot cut into them.
• Bar width compensation set for the substrate and the printing process used.
• Varnish and lamination held clear of, or selected for, the barcode field.
• Printed symbols scanned and verified against the supplied data before despatch.

Where a brand specifies a minimum verification grade, the achieved grade is reported with the delivery. Where a buyer supplies a data list of GTINs, the printed sequence is checked item by item against that list.

Compliance mark reproduction

EN 388 and other pictograms, CE marking, BIS marks, size markings, care symbols and recycling marks are reproduced at the sizes and proportions defined by the relevant standard or by the brand's artwork. Pictograms are printed from vector data. They are never rescaled from a low-resolution image, never re-drawn by hand, and never printed at a size where the performance digits inside the pictogram become unreadable.

Delivery commitment

A confirmed date is a date the plant has scheduled press time for. Because printing, lamination, silkscreen and finishing are all on one site, there is no queue in another factory that can move without notice. Where a shipment date moves forward, the remaining production steps can be re-sequenced the same day.

Delivered quantities are counted and banded in the sizes the packing line asks for, and short-shipment against an approved order is treated as a fault, not a tolerance.