The pope’s coffin is lined with zinc mainly to protect the body from moisture, insects, and other elements , while also helping decomposition proceed in a more controlled, “natural” way and keeping odors and fluids contained.

Practical reasons for zinc

  • Moisture and decay control : Zinc‑lined coffins act as a barrier against groundwater and soil, slowing down the breakdown of the wooden coffin so the remains stay more intact for longer.
  • Containment of fluids and gases : The liner helps seal in liquids and gases produced during decomposition, which is especially important in crowded vaults or tombs under churches.
  • Lighter and cheaper than lead : Zinc is lighter than traditional lead liners and less expensive, which fits Pope Francis’s stated preference for a simpler, more modest burial.

Why it’s used for popes

  • Tradition with a modern twist : Popes have long been buried in multiple coffins (often wood, lead, and another outer case); lining the inner coffin with zinc continues the idea of preserving the body while modernizing the materials.
  • Symbolic simplicity : In Pope Francis’s case, a plain wooden coffin lined with zinc reflects his wish for a humble, “in‑the‑ground” tomb without elaborate ornamentation.

In short, zinc lining is both a practical preservation measure and a way to keep papal burials dignified yet simpler and less costly than older lead‑lined designs.