Though stones are naturally resilient, it is important to preserve them to prevent any damage and increase their lifespan. Proper preservation of stones maintains the stone’s structure and boosts its durability. So what does preserving the stone mean? Preserving stone involves supporting it to withstand the harsh effects of the environment.

How To Preserve Stone?

Several methods are used to preserve stones, tailored to the specific type of stone. Generally, preservation involves coating the dry stone surface with substances like paraffin, linseed oil, or light paint, but in mind that this treatment is only temporary.

Regular washing of stone surfaces with water and steam helps to eliminate accumulated dirt and salts which ensures the preservation of the stone surface. Using preservatives like sodium silicate (or potash) and calcium chloride during washing is also highly effective.

Lead paint and coal tar are sometimes used for preservation, but they may alter the stone’s natural color.

Chemicals also help in stone surface cleaning but may introduce salts, potentially damaging the stone. In industrial areas, barium hydrate solution is effective for preserving stones.

Preservatives For Stone Prevention

A preservative is a substance, such as oil, paint, or solution, that is applied to a surface to protect it from harmful substances that can cause deterioration.

Key Characteristics of a Good Preservative

To call a preservative “best” it should meet some characteristics which are listed below –

1. Ease of application and penetration into pores
2. Ability to remain effective over time without leaching.
3. Cost-effectiveness.
4. Prevention of moisture penetration into the surface.
5. Absence of undesirable color changes.
6. Sufficient hardening to withstand atmospheric conditions.
7. Non-corrosiveness and safety.

One thing to point out here is that no preservative meets all criteria, so selection is based on the stone’s chemistry and location within the structure.

Commonly Used Preservatives

Below is a list of commonly used preservatives that are used by skilled professionals to preserve the stone.

1. Coal tar: May alter appearance and absorb heat.
2. Linseed oil: Raw form maintains the stone’s original shade but requires frequent reapplication; boiled form darkens the surface and lasts longer.
3. Paraffin.
4. Paints: Alter stone’s color; can be pressure-applied for deeper penetration.
5. Baryta solution (Barium hydrate): Reacts with calcium sulfate in stones to form insoluble barium sulfate, resistant to atmospheric effects.
6. Szerelmy’s solution: Mixture of sodium silicate and calcium chloride.
7. Alum soap solution: Combination of alum and soft soap in water.