Efflorescence & Limescale - Slate

Efflorescence and limescale can be challenging on slate, appearing as white salt deposits or hard, chalky buildup that detracts from the stone’s natural beauty. Efflorescence results from evaporating moisture leaving mineral salts on the surface, while limescale is caused by hard water deposits that settle over time. PureSeal’s efflorescence and limescale removers are formulated specifically for slate, effectively lifting these residues to restore the stone’s natural color and texture without damage.

For slate, we recommend using phosphoric acid rather than hydrochloric acid. Phosphoric acid offers a gentler, effective solution for dissolving mineral buildup, while hydrochloric acid can be overly aggressive, potentially reacting with any iron content in slate and causing rust spots or damage. Phosphoric acid breaks down deposits without harming the stone’s surface or integrity.