Printed Shrink Film: 8 Checks Before You Approve the Artwork
Printed shrink film can protect a multipack, carry branding and help products remain easy to identify through packing, storage and distribution. However, an artwork PDF that looks right on a flat screen does not automatically guarantee a good result after the film has passed through a shrink tunnel.
The finished appearance depends on the relationship between the artwork, film specification, reel construction, machine settings and the way the material shrinks around the product. That is why the best time to resolve potential problems is before cylinders or plates are made and production film is ordered.
This practical checklist explains the information to confirm when specifying printed shrink film for an automated packaging line.
1. Start with the product and pack configuration
The printer and film manufacturer need to understand the finished pack, not only the flat film width. Useful information includes:
• Product dimensions and weight • Number and arrangement of items in each multipack • Unsupported or tray-supported pack • Required carry points or finger holes • Expected storage and distribution conditions • Photographs or samples of an existing finished pack
A 6 × 4 bottle bundle behaves differently from a shallow tray of cartons. Corners, voids and changes in product diameter can all affect how the print is positioned and distorted during shrinking.
2. Confirm the correct film width and thickness
Printed artwork cannot compensate for film that is incorrectly sized. Film width must provide enough material to form and close the pack without excessive overlap, weak seals or loose presentation. Thickness must also suit the product weight, pack geometry, distribution demands and shrink tunnel.
Avoid copying the nominal details from an old invoice without checking the actual reel and finished pack. If the current film is running well, a reel label and physical sample provide a useful starting point. If it is not, measure the current specification and record the fault before changing several variables at once.
3. Agree the print repeat and cut-off position
The print repeat is the distance before the design repeats along the reel. It must correspond with the machine's pack length and cut-off control so that each design appears in the intended position.
Before approval, confirm: • Repeat length and tolerance • Direction of unwind • Print orientation on the reel • Front, back and side-panel positions • Registration-mark position and colour • Where the machine reads the registration mark
An incorrect unwind direction or eye-mark position can make an otherwise accurate print unusable on the line.
4. Allow for shrink distortion
Shrink is not identical across every part of the pack. Film close to corners, apertures, product shoulders and the tunnel airflow can move differently from a flat central panel.
Important logos, instructions and barcodes should therefore sit within agreed safe areas. Artwork may need to be pre-distorted so that it appears correct after shrinking. This is especially important when a design wraps around more than one face of the multipack.
The artwork proof should show the intended position on the finished pack, not only the flat web. A physical trial provides the strongest evidence where appearance is critical.
5. Protect seals and high-stress areas
Heavy ink coverage, coatings and design elements should be reviewed around seal zones. The film still needs to seal reliably, shrink evenly and withstand handling after printing.
Map the longitudinal and transverse seals on the artwork. Keep essential information away from seal overlaps, perforations, carry holes and areas that stretch heavily around the product. The exact approach depends on the ink system, film construction and packaging machine, so these areas should be agreed as part of the technical specification rather than left to the artwork studio alone.
6. Treat barcodes as functional elements
Barcodes must remain readable after printing, converting and shrinking. GS1 standards cover barcode dimensions, quiet zones, contrast and placement, but the finished pack and scanning environment still need to be considered.
Do not reduce or reposition a barcode simply to make the artwork look more balanced. Check the symbol at the intended size and orientation, keep it away from folds and distortion zones, and verify the final wrapped pack rather than relying only on the digital proof.
7. Match the reel to the packaging machine
The correct film formula and artwork can still perform poorly if the reel presentation does not match the machine. Confirm:
• Maximum reel diameter and weight • Core diameter and core width • Winding tension and reel hardness • Unwind direction • Print side and treatment side • Registration-mark reader requirements • Splice and reel-labelling requirements
These details influence reel handling, tracking, registration control and changeover time. They should be part of the approved specification for every repeat order.
8. Approve against a controlled line trial
Where practical, run a controlled trial using representative products and normal production conditions. Record the machine settings rather than adjusting the tunnel until the pack simply “looks acceptable”.
The trial should assess: • Print position on every face • Repeat and registration stability • Seal strength and appearance • Shrink around corners and openings • Barcode readability where relevant • Pack stability after cooling • Film tracking, breaks and start-up waste • Performance at the intended line speed
Agree the acceptance criteria before the trial. A signed finished-pack sample, approved artwork and recorded reel specification create a clearer reference for repeat production.
What should be included in the final specification?
The approved specification should connect the visual and technical requirements. As a minimum, retain the artwork version, colours, repeat length, registration-mark details, film width and thickness, material structure, reel and core format, winding direction, approved pack arrangement and trial standard.
If recycled content is being considered, test the complete printed film rather than assuming it will behave exactly like the existing grade. Appearance, sealing and shrink response must remain suitable for the application.
Printed shrink film support from Stretchband Packaging
Stretchband Packaging supplies bespoke printed polythene film and collation shrink film for automated packaging applications. We can review an existing reel, artwork brief, finished pack and machine details to help build a practical specification before a production trial.
If you are planning a new printed multipack or reviewing a film that is difficult to run, contact our team for a straightforward technical discussion. There is no obligation to change a specification that is already working well.
Related Stretchband Packaging resources
Printed films: https://www.stretchbandpackaging.co.uk/printed-films
Collation shrink film: https://www.stretchbandpackaging.co.uk/collation-shrink-film
Polythene film range: https://www.stretchbandpackaging.co.uk/polythene
No-cost film audit: https://www.stretchbandpackaging.co.uk/no-cost-film-audit
Contact Stretchband Packaging: https://www.stretchbandpackaging.co.uk/contact-us
