Score construction, seaming & where glass fits
What the format does brilliantly, and the one question to settle before specifying it.
A pull-ring end is a shell of aluminum with a score pressed into the panel and a tab riveted through it. Pulling the ring tears the score and lifts the panel out, which opens the container and destroys the closure in the same motion. It is applied by rolling a double seam onto a flange — a construction glass does not have.
Settle the container material first
A double seam is formed by rolling the curl of the end around the flange of a metal or composite body. Glass has neither flange nor ductility, so a glass bottle cannot take a seamed end. Where a glass program wants the ring-pull gesture, the equivalent is a pull-off crown on a 26 mm crown finish — the same one-pull opening, a completely different closure to buy.
Read the diameter code, not the millimeters
Ends are called out in the imperial can convention: 200 is 50.0 mm, 202 is about 52.3 mm, 209 is 63 mm and 307 is 83 mm. The figures describe the seaming diameter rather than the visible top, so an end and a body only pair correctly when both are quoted in the same code. Mixing a metric diameter into that conversation is where most sampling errors start.
Full aperture and stay-on tab are different products
A full-aperture end scores around the whole panel so the top lifts away and the customer can reach in — that is the format for nuts, powders and paste. A stay-on tab scores only a drinking hole and keeps the tab attached, which is the beverage-can convention. They share the ring but almost nothing else, and the choice drives both the score depth and the opening force.
The alloy is chosen for a controlled tear
Shells are pressed from 5182-H19 aluminum, a magnesium alloy stiff enough to hold the panel flat and predictable enough that the residual metal under the score fails at a consistent load. The tab is a separate blank riveted through the panel from a softer grade so it bends rather than snaps. Change either specification and the opening force moves with it.
The compound does the sealing, the seam holds it
A ring of sealing compound is lined into the curl and dried before the end is shipped; on 200 and 202 ends the dry film is typically controlled to 15–40 mg. During seaming that compound flows into the space between the curls of end and body. Too little and the seam leaks; too much and it extrudes into the pack, so it is inspected as a weight rather than by eye.
Inspect the edge the customer will touch
A torn score leaves a cut edge on both the removed panel and the rim, and full-aperture ends are used on products people reach into. Curl geometry, score residual and how the panel is designed to fold all decide whether that edge is safe. It is judged on units opened by hand the way a customer opens them, not on the specification sheet.
