Efflorescence: Why Your Stone is Turning White and How to Stop It

The Salt Bloom

Efflorescence occurs when water dissolves salts in the cement mortar bed and pushes them to the surface of the stone. As the water evaporates, it leaves behind a white, powdery salty residue that ruins the look of Kandla Grey or limestone.

Prevention is Key

Once it's there, it's hard to remove (acid washing helps but is risky). The best cure is prevention. Always prime the back of porous stones with an SBR (Styrene Butadiene Rubber) Slurry Primer before laying. This creates a waterproof barrier that stops the salts from migrating up from the cement into the stone.