Rollstock Specification Guide: Machine, Web Width, Repeat, Core and Wind Direction

Short answer: a rollstock order is only quotable once the converter knows the filling machine (or at least the format and machine model), the web width and print repeat, the core and wind direction, and the film's job — structure, sealant layer and barrier target. If all you have is "we need film for pouches," the fastest route to a useful quote is your current roll or a finished pack plus the machine model.

Rollstock — also called roll film or reels — is film supplied on rolls to run on form-fill-seal (FFS) lines, flow-wrappers, stick-pack and sachet machines. Unlike a finished pouch, a roll has no bag geometry yet: the machine forms it. That means every spec decision has to fit the equipment, not just the product. Get one variable wrong — repeat off by a few millimetres, print on the wrong face, a 6-inch core where the unwind mandrel takes 3-inch — and the roll will not run or will not register.

Foldveil supplies roll film for form-fill-seal lines in food, beverage and home care: blown film up to 9 layers with mono-material options, rotogravure/flexo print up to 12 colours, and solvent-based, solvent-free or water-based lamination. The steps below are the fields our technical review needs to recommend a structure and confirm a quote.

Start with the filling machine, not the film

The machine determines the geometry the film must fit. The first line of any rollstock brief should name the format, and ideally the machine model.

If you can share the machine model and its current film specification, the converter can reverse-engineer most of the missing fields. If not, state at least the format and the finished pack dimensions (width × height, or width × cut-off length).

Web width, thickness and roll diameter

Three physical-roll numbers matter before anything runs:

• Web width is the film width across the machine (the roll width). It is not the finished pack width.
• Thickness (micron or mil, or GSM for some films) affects seal energy, barrier and yield. State the unit, not just a number.
• Roll diameter and meters per roll must fit the unwind stand. State the maximum roll OD the machine accepts and the length you need.

Print repeat and eye mark

Print repeat is the distance between two identical printed points in the machine direction — one pack pitch. It must match the machine's cut-off or jaw length within tolerance, or the pack will drift out of register.

The eye mark is the printed registration mark the sensor reads to hold that repeat. State:

• eye-mark position (machine edge vs operator edge)
• print side (which face carries the print)
• sensor type if known (contrast vs transparent)

Core and wind direction

Two fields get missed most often and cause the most trial delays.

• Core: the inside diameter of the cardboard core — 3 inch (76 mm) and 6 inch (152 mm) are the most common — plus the core width. Match the unwind mandrel.
• Wind direction: which face of the film is out and which edge leads, usually stated as a numeric code (1–8). If you do not know your code, send a roll of film that currently runs and the converter will match it.

Sealant layer and seal window

The sealant layer is the inside layer that welds to itself. It must match the machine's sealing system — heat-seal bars, ultrasonic or impulse — and the product's fill temperature. State:

• sealant resin and seal type
• the seal temperature range the machine runs
• hot-fill, cold-fill or retort if relevant

Barrier and structure: mono vs multi-layer

The film structure carries the barrier, so choose it from the product's shelf-life target rather than a generic "we want good barrier."

• Mono-material film (PE- or PP-based) keeps the pack easier to recycle — relevant as EU PPWR recyclability grading pushes brands toward single-material structures. See our mono-material mailer structures comparison for how structure choice follows the disposal stream.
• Multi-layer film (with EVOH, metallization or foil) buys higher barrier but complicates recycling.

Specify a target barrier (moisture or oxygen transmission) rather than a hard number if you have no test data; the converter can recommend a structure and confirm values with an applicable test report. Like every Foldveil family, roll-film certification and test-document scope is verified per factory, material and production run — never stated as a blanket certificate.

What to send for a quote

A complete rollstock RFQ needs this minimum set:

• Machine type/model and format (VFFS, HFFS, flow-wrap, stick pack)
• Web width and maximum roll OD
• Print repeat, or finished pack width × height
• Core ID and width
• Wind direction code, or a running sample
• Print side and eye-mark position
• Sealant layer and seal temperature
• Structure and barrier target (OTR/WVTR)
• Quantity (meters or rolls) and destination market
• Food-contact / compliance market if applicable

Missing several of these? Send the roll or finished pack you run today plus your machine model — that is usually enough to start a technical review. If you are specifying a finished pouch instead of film, our stand-up pouch spec sheet covers barrier, zipper, spout and filling-line fit, and our spout pouch RFQ checklist walks through product, fill temperature and fitment.

When you are ready, request a quote with the checklist above — width, repeat and quantity are enough to open the conversation.

Reference

The section order above follows the SPMC white paper A Guide to Writing Rollstock Specifications (IoPP), aligned with ASTM F99, the standard guide for writing specifications for flexible barrier materials. It covers thickness, roll width, roll diameter, splices, core, print repeat and wind direction — the same fields a converter needs to quote and run the film.