What is stone sealing?

Stone sealing is the application of a protective treatment to a stone surface to retard staining and corrosion.

Why should you seal natural stone surfaces?

Natural stone is a porous material riddled with interconnected capillary channels that work similarly to a sponge. These channels cause capillary action to occur, which is the process of a liquid flowing in narrow spaces without the assistance of external forces. This action also draws in any other salts, minerals or solubles that have dissolved into the liquid, causing staining, etching and other damage like efflorescence. Some stones are much more absorbent than others. For example, sandstone is a very absorbent material, where granite is significantly less porous.

What is capillary action?

Capillary action is defined as the movement of water within the spaces of a porous material due to the forces of adhesion, cohesion, and surface tension. All liquids have cohesive properties, because of which all the molecules tend to stay together; this creates surface tension. Some liquids have adhesive tendencies by which they are attracted to substances unlike themselves.

Benefits of sealing your stone surface

• Stain prevention
• Reduce etching
• Preservation of stone
• Easier clean
• Efflorescence prevention

Common problems that occur when stone surfaces have not been sealed

– Stains

What causes stains in stone?

Stains occur when substances remain on the stone surface, and a liquid is present to carry pollutants into the stone’s pores. If a sealant is not present or worn over time, the surface will absorb the substance quickly staining the surface. Common stains include; rust from iron, copper, wine, fruit juices, oils and other organic stains.

Can you remove stains from stone surfaces?

Yes, we can remove many stains from stone surfaces; however, it is important to act quickly. To remove stains, we create a poultice mixture of a cleaning solution to dissolve the stain and absorbent material. This mixture is applied to the stain and covered with polythene and left for 24-48 hours. Some stains will require multiple applications.

– Etching

What is etching?

Etching is surface damage in stone surfaces that contain calcium carbonate. When an acidic substance meets with the calcium carbonate in the stone, it causes a chemical reaction damaging the stone’s surface, leaving what appears to be a dull mark or stain. Stones that have a higher concentration of calcium carbonate include; limestone, marble and travertine.

Can etching be fixed?

Yes, we can correct etching in stone surfaces. The process depends on how deep the etching has gone into the stone. Firstly we would attempt to remove a slight etching with special polishing powders. If the etching has penetrated deeper into the surface, we will use diamond polishing pads to wear down the stone surface until we have reached a level that is not damaged. We then polish to the desired finish and apply a sealant to help prevent further damage in the future.

– Efflorescence

What is efflorescence?

The sponge-like quality of stone absorbs water and any salts that have dissolved. This salt material rises to the surface, leaving a dusty white appearance. This typically occurs in stone surfaces that have not been sealed on the back before being laid in external applications.

Can efflorescence be fixed?

Yes, we can remove efflorescence. To do this, we use a special product that is applied and agitated in a manual process. This dwells for a time and is removed, vacuumed, and we clean down the area.

Different types of stone sealers

What is an impregnating stone sealant?

An impregnating sealer is a deep penetrating sealer that forms a chemical and mechanical bond to the treated surface.

What is a penetrating stone sealant?

A penetrating sealer is a sealer that penetrates deep into the surface of the stone, where it chemically reacts below the surface from within the pores.

What is a topical/surface stone sealant?

A topical sealer provides protection by forming a film on the surface.

What is an enhancing stone sealant?

Enhancing sealers highlight the natural characteristics of the stone without creating a gloss or shine.