Two components are easy to confuse
The closure card is the structural paperboard disc that closes the opening. The printed face paper is the decorative sheet applied to a visible end surface. They may share artwork, but they are separate controlled components with different dimensions in a paper-flat construction.
Paper-flat end: close the inside, finish the outside
In Folvar’s paper-flat route, the closure card matches the shape formed by the tube’s inner diameter. A separate printed face paper extends to the outer diameter. Covering the full outer profile hides the raw tube cut and creates a more visually continuous top or bottom. The two operations should remain separate in the engineering and artwork records even when the customer sees one finished face.
Inner curl: the tube wall becomes the support
For an inner-curl end, tooling presses the outer tube wall inward. The curved wall forms a ledge inside the circumference and supports the closure card. The card and its printed face correspond to the inner opening geometry, while the curled tube edge remains visible around them. The curl is part of the side wall, not a separate ring added after the card.
| Decision | Paper-flat end | Inner-curl end |
|---|---|---|
| Closure card | Matches the inner shape | Matches the supported inner opening |
| Printed end face | Separate sheet reaches the outer profile | Follows the closure-card/opening geometry |
| Tube cut edge | Covered by face paper | Formed into a visible inward curl |
| Side-wall allowance | Finished height plus normal trim logic | Finished height plus curl feed at the curled end |
| Visual character | Flush, uninterrupted face | Recessed face with a tactile paper rim |
Curl allowance belongs in the dieline
Folvar currently uses 2–4 mm per curled end as an engineering starting allowance, depending on board thickness and the forming setup. A common board layer is around 0.8–1.0 mm, but the actual caliper must be recorded rather than inferred from grammage. The allowance is not decorative bleed: it is material that continues beyond the visible finished height and is consumed by the inward forming operation.
What the production file should show
Required surfaces and references
- Body trim, bleed, paste zone and front-centre line.
- Finished visible-height line and any additional curl-feed band.
- Top and bottom structural-card geometry based on the approved inner dimensions.
- Separate outer-diameter face-paper geometry where the paper-flat route requires it.
- Lid/base assembly cut and alignment line for a two-piece structure.
- A front view tied to the same structure version so the flat file is not reviewed in isolation.
Material language still needs evidence
An all-paper-looking end does not by itself establish water resistance, grease resistance, food-contact suitability, recyclability in every market or shelf-life performance. Paper tests such as thickness, grammage and Cobb water absorptiveness describe specific material properties under defined methods. Finished-pack performance must be supported by the actual material specification and any tests required for the intended product and market.
A simple choice test
Choose the paper-flat route when the design needs a clean end face that reaches the full outer profile and conceals the cut edge. Consider the inner curl when the visible paper rim and recessed face support the intended expression and the forming route is approved. In both cases, confirm the end construction before asking a designer or image model to generate the top view—otherwise the visual may be attractive but physically wrong.