Why Does Green Marble Warp? The Moisture Sensitivity of Serpentinite

The Curling Phenomenon

Installers are often shocked when a slab of Rainforest Green or Udaipur Green starts to lift at the corners (curling) weeks after installation.

The Geology

Green marble is technically Serpentinite. Unlike calcium-based marbles, it contains minerals capable of absorbing water molecules into their crystal lattice. If you use a water-based cement adhesive, the bottom of the tile absorbs water and expands, while the dry top does not. This differential expansion causes the tile to bowl/curl upwards.

The Installation Fix

NEVER use water-based thin-set mortar. You must use a 100% Epoxy Adhesive or a polyurethane-based adhesive. These contain no water, preventing the chemical reaction that causes warping. Always seal the back of the stone before installation.