What causes canned beverage leaks and seaming failures, and how can producers prevent them?

Leaking cans are a persistent quality-control challenge in canning. The root causes are multiple and often interconnected, so diagnosis and prevention require attention to several factors.

**Primary causes:** - **Internal liner failure** — the most common cause of leaks - **Seam defects** — poor can seaming during the canning process itself - **External product contamination** — low-pH liquids (sub-6 pH) can corrode the unlined outside of cans over time; once one can leaks, product spreads to neighbouring cans, triggering a cascade failure (members report losing whole pallets this way) - **Carbonation levels and pasteurisation interaction** — some members solved leaks by changing recipe or adjusting carbonation; one member switched to **Jolly's** (which uses Velcorin dosing instead of pasteurisation) and resolved recurring issues - **Can stacking and storage conditions** — physical pressure during storage and shipment can accelerate failures

**Prevention tactics members recommend:** - **Store sample cans upside down for a minimum of 10 days post-production** — this is the key early-warning step. Members caught a seam issue with lids from **Ardagh** only after loading a container for US shipment; upside-down storage would have flagged it before market - **Review your recipe and carbonation levels** — members found that recipe changes (including carbonation adjustment) eliminated leaks they'd previously blamed on canners - **Ask your canner about product handling** — ensure cans are not receiving external product contamination during the filling process - **Check your pasteurisation temperature and carbonation pairing** — if you pasteurise, discuss your specific temp/carbonation combo with your canner to rule out interaction issues

**Canner recommendations from experience:** - **Bottled & Canned** (bottledandcanned.co.uk) — praised as "the most pro" by one member; handles low volumes (1,000–2,000L) - **Jolly's** — preferred by several members, uses Velcorin dosing; some had early leaking issues but resolved them by switching recipes - **Can It in Bolton** — described as "very good" with decent MOQs and lead times - **Ardagh** — supply can lids; at least one seaming issue reported

**Caveats:** - Leaking can issues are "real and almost impossible to eliminate completely" - Multiple members reported mixed results even with the same canner (e.g., 2 SKUs fine, 1 "a total write-off" with Bottled & Canned; early leaks with Jolly's that resolved after recipe change) - Blame is often unclear — members acknowledge leaks may stem from recipe, canner process, storage, or a combination - Upside-down storage test is critical and should be mandatory before shipping