Weck
A genuinely plastic-free sealing system that predates the plastic era: glass jar, glass lid, natural rubber gasket, and stainless steel clamps, with no plastic anywhere in the closure. The listed jars rate plastic-free with zero metal-to-food contact, so acidic foods and ferments sit only against glass and natural rubber. Weck doesn't need to market plastic-free — the century-old design simply never introduced it. This is the real thing, not a marketing posture.
How clear are their specs?
Nothing to obscure — glass, natural rubber, and stainless are all visible and named, with no coatings, liners, or plastic components in the sealing system.
