01
A complete roll stock specification has four connected parts
| Specification area | What it controls |
|---|---|
| Material and performance | Product protection, stiffness, toughness, barrier, forming, sealing, slip, surface and compatibility |
| Web and print geometry | Fit to equipment, repeat, lanes, eye marks, registration, cut-off, seams, folds and graphic orientation |
| Roll construction | Core, diameter, weight, winding, tension, splice, roll edge, telescoping and handling |
| Production approval | Equipment, speed, settings, trials, acceptance criteria, retained samples and change control |
02
1. Material and functional performance
Name the construction when it is known, but also record why the structure works. Two films described with the same material names and nominal gauge can differ in resin selection, orientation, layer distribution, treatment, adhesive, sealant, slip, stiffness, and surface characteristics.
Structure
Layer order from outside to inside, material identity, nominal layer gauges when controlled, total gauge, adhesive or tie layers, coatings, metallization, foil, and sealant.
Barrier
Oxygen and moisture transmission targets with test conditions, plus light, aroma, grease, chemical, or flavor protection where relevant.
Mechanical behavior
Tensile, elongation, puncture, tear, flex-crack, stiffness, dead fold, forming, shrink, cold toughness, or abrasion as required by the application.
Surface behavior
Inside and outside coefficient of friction, treatment, printability, seal contamination tolerance, blocking, static, and release.
Seal response
Sealant compatibility, initiation temperature, operating window, hot tack, final seal strength, peel or permanent seal, pressure and dwell sensitivity.
03
2. Web, repeat, and print geometry
Web width
Nominal width, tolerance, slit-edge expectations, and whether the dimension includes trim or unused lanes.
Repeat
Machine-direction repeat, cut-off relationship, tolerance, and whether the repeat is measured to eye mark, print reference, or finished package.
Unwind
Which side of the web faces out, print orientation, leading edge, roll direction, and the equipment-specific unwind diagram.
Eye mark
Size, color, contrast, location, clear area, lane relationship, and the sensor requirements confirmed by production.
Lanes and registration
Number of lanes, lane width, cross-web position, graphics-to-cut and color-to-color tolerances, and required print-free seal areas.
04
3. Core and roll construction
| Roll item | Questions to resolve |
|---|---|
| Core | Inside diameter, material, wall, width, condition, chuck or mandrel needs, and whether the web is centered or offset |
| Roll limits | Maximum and preferred diameter, maximum weight, minimum usable footage, and equipment or lifting limitations |
| Winding | Print in or out, winding tension, roll hardness, edge alignment, telescoping limit, blocking risk, and start/end attachment |
| Splices | Permitted type, maximum count, flagging, location restrictions, strength, sensor requirements, and whether splice footage is excluded |
| Identification | Item and revision, lot, roll number, footage or weight, direction, lane, date, traceability, and barcode needs |
05
4. Record the line requirements
Record equipment type and model, forming set, web path, normal and target speeds, temperature zones, pressure, dwell, cooling, tension, product drop, and observed sensitivity to curl or friction. For existing films, keep the settings and performance range associated with both good and poor runs.
When qualifying a replacement, agree on which variables will remain fixed, what may be adjusted, how waste and downtime will be recorded, and what constitutes a successful trial. Changing the film and many machine settings simultaneously makes the result difficult to interpret.
06
What to provide when matching or resourcing an existing web
- Send the current controlled specification and artwork or web-layout revision.
- Provide full, legible roll-label photographs and an unopened roll when practical.
- Preserve representative finished packages and flat web from known good production.
- Share equipment, speed, forming, sealing, tension, registration, and recurring defect information.
- Identify which characteristics are mandatory, which are legacy descriptions, and which may be optimized.
- Define laboratory comparison, line-trial quantity, acceptance criteria, and approval owners before production supply.
FIELD CHECKLIST
Information to collect
Use this as a working prompt, then adapt the final specification or validation plan to the actual application.
- Product, target shelf life, fill condition, and protection requirements
- Full layer construction, total gauge, sealant, and print location
- Barrier values and test conditions
- Inside/outside COF, stiffness, curl, hot tack, and seal window as applicable
- Web width, tolerance, repeat, lanes, unwind, and print orientation
- Eye-mark size, color, position, contrast, and sensor requirements
- Core ID, core width, maximum roll diameter and weight
- Winding, edge alignment, tension, splice, and roll-identification requirements
- Equipment, forming geometry, normal speed, and seal settings
- Trial plan, acceptance criteria, retained samples, and change control
COMMON QUESTIONS
Questions worth resolving
Why can a replacement film with the same structure run differently?+
Named layers and total gauge do not fully describe resin selection, layer distribution, stiffness, curl, friction, treatment, adhesive, sealant, hot tack, winding, and roll build. Those differences can change tracking, forming, registration, sealing, and release.
Who should confirm unwind direction?+
The co-manufacturer or production team should confirm the equipment-specific unwind using a diagram or marked sample. The converter should then reflect that approved direction in the web layout, artwork, and roll identification.
REFERENCES & TEST METHODS
Test methods and acceptance criteria should be selected for the actual application. These standards and technical sources support the principles discussed in this guide:
ASTM F1921/F1921M: Hot seal strength (hot tack) of flexible webs↗ASTM F2029: Laboratory heat seals for flexible barrier materials↗