Closures and the seal
Updated
On this page7
Neck finish is the measurement
Not the diameter by eye and not the look of the thread. Every container page lists the closures verified against its own neck. On this shelf the finishes run to 63TW, 58-400, 70-450G and 58TW among others, and the wide formats narrow the choice more than people expect.
What the liner is for
Keeping oxygen out, because the product oxidizes, and keeping moisture out, because the product seizes. Both are slow failures that show up months later in somebody else’s cupboard, which makes the liner easy to treat as a detail and expensive to get wrong.
No vacuum means no seal indicator
A hot-filled jar tells you it sealed by pulling its lid down. A cold-filled nut butter gives you nothing, so a closure that did not seat properly looks exactly like one that did. That shifts the check from inspecting jars to controlling the capping, and to the rim wipe before it.
Tamper evidence is expected in this category
Buyers expect a seal they break, partly because of this product class’s history. A tamper-evident closure or band is close to a requirement of the shelf rather than a premium feature, and its absence is noticed.
Buy closures to match actual use
Jars and closures are consumed one for one, which sounds obvious and is routinely got wrong by ordering each in whatever case quantity it comes in. Work the ratio from a real run.
Fill weight, not fill level
A thick product does not settle to a level the way a liquid does, so filling by eye gives a jar that is legally underweight or one that is giving product away. Filling to a weight fixes both and it also keeps the headspace consistent, which is part of the shelf life.