Can Liner Terminology: Why "BPA-NI" Doesn't Guarantee a Safe Liner

A canned beverage producer used cans from the same supplier for months without issue. Then, without warning, several 2024 production runs developed a "rotten egg" smell and visible corrosion within a month of canning. The cans had been specified as "Gen II," "BPA-NI," and "Hard-to-Hold" liner — exactly what the winery thought it had ordered. So what went wrong?

The problem is industry jargon. Terms like "Gen II," "BPA-NI," and "Hard-to-Hold" describe liner generation, whether a liner avoids bisphenol A, and liner thickness — but none of them specify the actual polymer chemistry of the liner. A liner can satisfy all three labels and still be an unsuitable material for wine.

That's exactly what happened in this case. The supplier's contract specified "Hard-to-Hold," "BPA-NI," and "Gen II" — and initially delivered cans with valPure V70 (a BPA-non-intent epoxy) at the correct thickness, which performed fine. In mid-2024, the supplier switched to a new liner that still met all three contract terms but was based on acrylic instead of epoxy. FT-IR analysis confirmed the swap. Accelerated aging tests (3 days at 50°C in a high-SO2 test wine) showed the new acrylic liner produced roughly 10x more hydrogen sulfide (H2S) than the original epoxy liner — despite both liners technically satisfying the same contract language.

Why liner chemistry matters for wine specifically: an unlined aluminum can will start leaking within weeks because wine's acidity corrodes aluminum, and sulfites in the wine react with the exposed metal to produce H2S. Cornell research has identified three liner materials that reliably keep H2S low (under 10 µg/L, near the sensory threshold) after ~6 months at room temperature: traditional BPA epoxy, valPure V70 (a BPA-NI epoxy), and aTULC (a thick laminated polyester). Acrylic and thinner polyester liners, by contrast, can produce over 10 µg/L H2S in less than a week when paired with a sulfited beverage.

Practical takeaway for canned wine and cider producers: don't rely on generic industry shorthand when specifying liners with a can supplier, especially one who isn't the can manufacturer (a common arrangement, since many suppliers also handle artwork and packaging and may not use terms the same way the manufacturer does). Name the actual liner material in the contract — BPA epoxy, valPure V70, or aTULC — at the thickest available grade, and require written approval before the supplier substitutes anything, even if the substitute still satisfies the original labels on paper.

Source: "Wine or cider can liner terminology – precision matters!" Cornell CALS, August 2026 (Gavin Sacks, Austin Montgomery, Anike Abegunde, Julie Goddard, Héctor Ramírez).