Technical specification guide · Roll labels
Roll Label Setup Guide: Unwind Direction, Core Size, Gap & Roll Orientation
A label may have the correct artwork and material yet still be supplied in a roll format that does not feed an applicator as expected. Confirm the machine's feed path and roll limits before you approve the label specification.
Quick answer
What must a machine-applied roll label specification include?
State the machine application direction and leading edge, the label's orientation on the web, inside or outside winding, core inside diameter, maximum roll outside diameter, web width, label size and gap. Confirm these against the applicator manual and an actual roll sample. A numbered “unwind position” alone can be ambiguous because charts use different viewing conventions.
01 / Fit the applicator
Why roll setup matters
Machine application depends on the way the web leaves the roll, travels through the applicator and presents each label at the dispense edge. If the orientation is wrong, the applicator may present the label upside down or with the wrong side leading. A mismatched core or roll diameter may prevent loading; a gap that does not match the sensor setup may affect registration. These are project checks, not statements about a universal machine setting.
Start with the applicator model and its documented roll requirements. If the equipment team can supply a photo or diagram of the feed path and a proven roll sample, include them in the RFQ. The production drawing should name the viewing direction used for any unwind diagram.
02 / Direction
Unwind direction, winding side and label orientation
Unwind direction describes how labels leave a roll relative to the printed face and the leading edge. It is tied to the applicator's feed path, not to how a loose label looks on a screen. Specify whether the printed labels face outside or inside on the wound roll, then show which edge of the label reaches the dispense point first.
Schematic only. It does not prescribe a numbered unwind position or machine direction.
Inside wound versus outside wound
With outside winding, the printed face is on the exterior of the roll. With inside winding, it faces toward the core. The applicable choice depends on the feed path and how the label must reach the product. Ask the machine operator to confirm the required winding side; do not infer it from a catalog image.
Leading edge and panel orientation
Mark top, bottom, left and right on the label artwork and identify the edge that must leave the liner first. For a cylindrical product, also identify the direction of product travel and the side that faces the consumer after application. An orientation sketch should show both the roll view and the finished product view. If a supplier uses an unwind number, include the diagram because numbering systems can differ.
Barcode and QR orientation
State where codes should sit after application and whether scanning occurs before or after the label is on the product. Avoid placing a code across a high-curvature edge or another area that compromises the intended scan. Verify the final code on an applied sample using the actual scanner and lighting conditions; no artwork proof alone establishes readability.
03 / Roll geometry
Core ID, roll OD, gap and web width
Core inside diameter
Core ID is the opening that fits the applicator mandrel. Specify the required inside diameter and the acceptable core construction from the machine documentation. “Core size” without ID or unit is incomplete.
Maximum roll outside diameter
Maximum roll OD limits the physical roll that can fit and turn in the machine. Confirm available clearance, roll mass and the equipment's stated limit. The desired label count per roll is a separate input and may change the final OD.
Label gap
The gap is the liner space between consecutive labels in the feed direction. It works with the applicator sensor and registration settings. Provide the machine's required range or an approved sample; do not assume one standard gap for every line.
Web width and label dimensions
Web width includes the label and liner margins across the feed. State label width and length with the feed direction identified, plus the web-width limit from the applicator. A 90-degree artwork rotation changes which label dimension travels along the web.
Also confirm liner material or sensing method if the machine requires it. These inputs should be reviewed together: a label may fit the bottle yet be too wide for the applicator web path.
04 / Application method
Machine-applied and hand-applied rolls need different decisions
Machine-applied labels require the feed path, unwind direction, core ID, maximum OD, gap and web width to align with the applicator. The equipment owner should approve an applied sample at the intended line speed and product orientation. A hand-applied roll may allow more flexibility in unwind direction, but roll handling, visible label orientation and consistent placement still matter.
If the project has not yet chosen roll versus sheets, the roll labels versus sheet labels machine application guide addresses that format decision. This page assumes a roll format and focuses on the roll's production specification.
05 / Specification table
Record each machine input before requesting a quote
| Field | Buyer or equipment team provides | Approval evidence |
|---|---|---|
| Machine & feed path | Applicator model, manual or photo, product travel direction | Operator review |
| Unwind & winding | Printed face in/out and labeled direction sketch | Physical roll orientation |
| Leading edge | Which artwork edge dispenses first | Applied sample |
| Core ID | Inside diameter, unit and machine requirement | Mandrel fit |
| Maximum roll OD | Equipment limit and target labels per roll, if known | Loading clearance |
| Label gap | Sensor requirement or approved roll sample | Registration check |
| Web width | Machine limit and liner margin requirement | Web-path fit |
| Label size | Width × length and feed direction | Applied product review |
| Artwork & codes | Current file version, code data and orientation | Print proof and scan test |
Leave unknown machine values marked pending until the equipment team confirms them. In particular, do not convert a supplier's familiar core or gap into a project requirement without checking the applicator.
06 / Before production
Pre-production approval checklist
- Confirm label dimensions on the actual product and mark the desired consumer-facing orientation.
- Obtain the machine's core, OD, web-width, gap and liner requirements.
- Agree on one unwind drawing that names the viewer's perspective and leading edge.
- Check the print proof and variable-data content against the controlled artwork version.
- Test an actual roll on the intended applicator, including dispense, registration and applied appearance.
- Record any change to material, label size, winding or equipment setting before final approval.
For general artwork preparation, see the print-ready artwork guide. The roll setup drawing and machine trial should accompany the artwork approval rather than be inferred from it.
Questions buyers ask
Roll label setup FAQ
Can I specify only an unwind number?
Include a diagram showing the printed face, viewing direction and leading edge. Numbering conventions can differ, so the diagram and machine feed path are the controlling references.
Is core size the inside or outside diameter?
State core inside diameter explicitly, with units, and confirm it against the applicator mandrel. Also specify the maximum finished roll outside diameter separately.
How do I choose the label gap?
Use the applicator's sensor requirement or an approved roll sample. Gap is measured along the feed direction between labels and should be verified on the machine.
Does hand application need the same unwind detail?
Hand application is usually less dependent on a fixed feed path, but roll handling and presentation still deserve confirmation. Machine application needs the full equipment specification.
Will a PDF proof confirm machine compatibility?
No. A proof checks visual content. A physical roll trial checks loading, feeding, orientation and the applied result on the intended equipment.
Ready to discuss a roll-label project?
Send the machine inputs with the artwork
Share the applicator model or feed diagram, label size, roll limits and a proven sample if available. These details help define a roll-label specification for review and sampling.
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