Same Liner, Different Can Maker: Why H2S Varies Even Between "Identical" Cans

If two can suppliers both use the same liner chemistry, should their cans perform the same way with wine? A Cornell follow-up study says no — and the gap can be large enough to matter.

Researchers sourced ten can types (three BPA epoxy, five BPA-NI epoxy, two acrylic) from five different commercial manufacturers, coded V through Z. Two of the manufacturers' cans — designated Y2 and Z2 — both reportedly used the exact same liner material, Valspar V70. Despite that, cans from manufacturer Z2 produced roughly six times less H2S than Y2 when filled with the same high-molecular-SO2 wine and aged for four months (5.9 µg/L versus 36.6 µg/L average). Z2 even outperformed X1, which used traditional BPA epoxy — long considered the "gold standard" liner.

The researchers dug into unused cans from each source to figure out why, testing aluminum alloy composition (X-ray fluorescence), liner chemistry (FTIR), and liner thickness/uniformity (laser profilometry and interferometry). Alloy composition and liner chemistry looked essentially identical between the well- and poorly-performing cans. The one measurable difference was liner thickness: the better-performing Z2 cans averaged about 10% thicker liner than Y2, and a clear inverse relationship held across all ten can sources — thinner average liner and higher liner thickness variability both tracked with more H2S. Notably, several other tests that manufacturers commonly use for quality control — enamel rating (a corrosivity proxy using an applied electrical current) and electrochemical impedance spectroscopy — did NOT distinguish good cans from bad ones when performed on unused cans, meaning these standard manufacturer QC checks may not catch a problem before it ships.

Batch-to-batch variation within a single manufacturer also showed up: one visually defective batch (Y2-2, with visible gaps in liner coverage) produced roughly 10x more H2S than the manufacturer's normal batch of the same liner. And the study reconfirmed that acrylic liners are unsuitable for wine regardless of manufacturer, generating far higher H2S than any epoxy liner tested, with additional variation between acrylic suppliers on top of that.

Practical takeaway: don't assume a liner name ("BPA-NI," "Valspar V70," etc.) is a complete spec. Different manufacturers using the same nominal liner material can perform very differently, and standard pre-shipment QC tests (enamel rating, EIS) may not catch it. The only reliable way to qualify a new can source is to run an actual storage or accelerated-aging trial with your wine before committing to a full production run.

Source: Sheehan, Suarez, Benefeito, Goddard & Sacks (2024), "Hydrogen Sulfide Formation in Canned Wines: Variation Among Can Sources," American Journal of Enology and Viticulture 75:0750003.