Dielines and print tolerances for private-label artwork

Most private-label artwork problems are not design problems. They are geometry problems that surface after the print cylinders have been cut, which is the most expensive possible moment to find them. This note covers the two things that decide whether artwork survives production: the dieline, and the tolerances around it.

What a dieline actually is

A dieline is the flat, unfolded drawing of a pack, at final size, with the folds and cuts marked. For a printed bag it is the film web layout; for a retail box it is the die board drawing; for a flow wrap it is the repeat length and the seal zone.

A dieline is a production document, not a design template. It carries the trim size, the bleed, the seal or glue zones, the fold positions and the position of any hanging hole, tear strip or window. Anything drawn outside those boundaries is either trimmed away or, worse, printed across a seal where it will not bond.

The dimensions that matter most

• Finished size after sealing and filling, not before. A stand-up pouch loses 15 to 25 mm of usable height to its gusset and seal.
• Seal zones. Typically 8 to 12 mm. Nothing important goes there: no text, no barcode, no brand mark, and no dark ink, because dark ink over a seal weakens the bond.
• Repeat length for flow wrap. The print repeats every X millimetres, and the artwork has to close cleanly at that pitch. Artwork built without knowing the pitch will either not repeat or will need a custom cylinder.
• Bleed. 3 mm is the common minimum; 5 mm is safer on film, which stretches slightly during sealing.
• Quiet zone around the barcode. At least 3 mm of unprinted space on all sides, plus contrast. Retail scanners fail on low-contrast or crowded barcodes far more often than brands expect.

Tolerances you should assume, not hope for

Print registration on film is not exact. Flexographic presses on film typically hold register within roughly 0.3 to 0.5 mm in steady running, with more variation at start-up and at speed changes. That number sets the real design rules:

Element	Rule of thumb	What goes wrong otherwise
Minimum text size	6 pt, 7 pt on film	Fills in or breaks up at speed
Reversed (knockout) text	8 pt minimum, no fine serifs	Ink bleeds into the counters
Hairlines	0.25 mm minimum	Disappears or prints unevenly
Colour-to-colour register	Assume 0.4 mm drift	Visible white gaps on butt-registered blocks
Trapping	0.1 to 0.2 mm overlap	Hairline gaps where two colours meet
Total ink coverage	Keep below roughly 300%	Set-off, blocking on the reel, slow drying

The practical consequence: avoid fine detail in small type, avoid butt-registered colour blocks with no overlap, and design for a slightly heavier line weight than looks right on screen. Artwork that looks crisp at 100 per cent on a monitor is often too fine for film.

Colour: what actually happens to your brand colour

Brand colours are usually defined in a spot reference. On a four-colour process press, that spot colour is built from four inks, and the build will not match the reference exactly, especially in the reds and deep pinks this category leans on. Two options:

• Add a spot ink. Exact brand colour, one extra plate, one extra print station, higher cost per unit and per cylinder. Justified when the colour is the brand.
• Accept a process build. Cheaper and adequate for most private label, but you must approve a physical proof rather than a screen proof.

Either way, approve a drawdown or a printed proof on the actual substrate. Film, matt laminate and coated paper all shift colour, and a screen proof cannot show you any of that.

The approval sequence that avoids reprints

• Dieline issued by the factory, with sizes and zones marked, in a vector format you can place artwork into.
• Artwork placed on that dieline at 1:1, with all text converted to outlines and a full font list supplied separately.
• Pre-press check for bleed, seal-zone conflicts, barcode quiet zone, minimum type size and ink coverage. This is where most defects are caught for free.
• Physical proof on the production substrate, approved in writing before cylinders are cut.
• First-off sample from the actual run, retained as the reference for later batches.

Every step you skip in that sequence reappears later as a reprint, and a reprint costs the cylinders again.

Regulatory text on pack

Leave room for it at the dieline stage, not the artwork stage. Depending on market, a pack may need the importer or responsible person address, material composition, a batch code, a manufacture or expiry date, recycling marks, and text in one or more languages. In the European Union, a three-language pack can consume most of the back panel before any marketing content is placed.

Send the dieline, the target market and the pack count with the enquiry, and the panel plan can be quoted together with the print, rather than discovered as an extra revision round.