38 mm or 76 mm: the core size that ruins a container
It is a cardboard tube. It costs almost nothing, it appears near the bottom of a specification sheet, and getting it wrong can make an entire shipment unsaleable in the market it was bought for.
38 mm for household retail foil — short rolls, hand-held dispensers. 76 mm for catering — long rolls mounted on a commercial spindle, where the core has to carry the roll's weight without deforming. The two are not interchangeable at the same width, and the mistake is discovered at the point of use, not at goods-in.
The core does two jobs: it locates the roll on a dispenser, and it carries the wound weight. The first matters for compatibility, the second for whether the roll stays round. Both fail silently until someone tries to use the product.
The comparison
| 38 mm core | 76 mm core | |
|---|---|---|
| Fits | Domestic dispensers, counter-top cradles | Commercial wall and bench dispensers |
| Typical roll length | 5–100 m | 50–300 m |
| Typical width | 250–450 mm | 300–600 mm |
| Load on the core | Low | High — a 300 m roll is heavy |
| Failure mode if wrong | Roll falls off the spindle | Core crushes, roll goes oval, foil feeds unevenly |
| Used by | Retail, household, e-commerce | Restaurants, bakeries, distributors |
Why weight decides it
A 300-metre roll at 15 μm and 450 mm wide carries a substantial mass wound on a tube. Under that load, a 38 mm core will deform — not immediately, but over weeks of standing on a shelf, and faster once it is mounted horizontally and pulled against.
A deformed core produces a roll that is no longer circular. The foil then feeds with varying tension, tears at the dispenser edge, and the operator compensates by pulling harder, which makes it worse. The product is not defective. It was simply specified for the wrong duty.
Most often when a buyer with a household background moves into food service. The width and thickness look familiar, the price looks attractive, and the core is copied from the previous order. It is caught at the first delivery to a restaurant, not at the port.
The other number: outer diameter
Core size gets the attention; outer diameter causes the second-most problems. A dispenser has a maximum roll diameter it will accept, and a 300 m roll at 15 μm is a large disc.
If your market uses a specific dispenser brand, the useful question is not "what core?" but "what is the maximum outer diameter this unit accepts?" Ask it before ordering, because the answer constrains the length you can sell, not just the roll you can buy.
Core quality, briefly
Two cores of the same diameter are not the same core. The variables that matter:
- Wall thickness and board grade — thin board crushes under load regardless of diameter
- Spiral vs convolute winding — spiral is standard; convolute is stronger but dearer
- Moisture content — damp core board transfers moisture to the inner wraps of foil, which is where corrosion starts
- Bore tolerance — a core that is 1 mm oversize will wobble on a spindle
This is a place where a supplier can quietly save money without changing the specification on paper. If a repeat order arrives with softer cores than the sample, that is a signal worth acting on — see evaluating a supplier.
Frequently asked questions
Can I get a 76 mm core on a household-length roll?
Physically yes, commercially rarely. It would not fit a domestic dispenser, so there is almost no market for it. If you are supplying both channels, keep two core specifications rather than compromising on one.
Does core size affect the price?
Marginally — a few percent at most, from the board cost and the rewinding setup. It is the cheapest specification decision you will make and the most expensive one to get wrong.
What about plastic cores?
Used in some markets for moisture resistance and reusability, but they add cost and create a disposal question for the end user. Cardboard remains standard for both household and catering foil.
Sources
- ISO 11093 — Paper and board, testing of cores.
- Related: Catering foil roll specifications.