Stone efflorescence

The accumulation of salts and mineral deposits resulting from the evaporation of water from the mortar behind the stone and the composition of the stone itself causes efflorescence and white deposits to appear on its surface. Stone efflorescence is a completely natural phenomenon because natural stone contains compounds such as sodium sulfate and calcium sulfate. On the other hand, the type of mortar used behind the stone is also highly important.

Causes of Stone Efflorescence

 Efflorescence tends to occur more frequently in areas with high humidity. This is because salt and minerals are transported more easily to the surface of stones due to moisture. Conversely, when the density of stones is lower, the saline solution will reach the stone’s surface more readily and evaporate more quickly. To prevent this from happening, highly porous travertine stones are often treated with resin and epoxy to make them resistant to penetration.

So generally, the reasons for efflorescence can be summarized in the following cases:

• The presence of minerals and salts in the mortar and stone composition.
• The humidity of the area.
•  A low density of stone

In the gallery below, you can see some examples of efflorescence on the surface of travertine stones that have low quality.

Prevention & Removal of Stone Efflorescence

We briefly mention several ways of preventing and removing efflorescence:

• Utilizing washed sand with lower levels of salt and sulfate compounds.
• Using a mechanical method, such as installing stone on the facade with screws, plates, and pins.
• Applying resin and epoxy to stone can make it glossy and impermeable, but not completely impenetrable.
• Using a rough cloth or sandpaper to abrade the stone’s surface is not recommended, as it may cause scratches.
• Cleaning with water and a brush is only a temporary solution, as the issue may reappear once the surface dries.
• Nano products with hydrophobic properties can greatly minimize water absorption and function as stone anti-efflorescence agents.
• To remove efflorescence, dilute hydrochloric acid with water and apply it to the stone. Use hydrophobic materials for a lasting solution.