Athena Stonecare: What Does It Mean to Seal Your Stone?

Most natural stone should be sealed before and after installation, and all of our restoration treatments include the application of a sealant. There is a lot of misconception about what this means for the stone, how it works and why it doesn’t give 100% protection. Here we explore the world of natural stone sealants.

Impregnating sealants penetrate the capillaries of the stone and protect from within. They can leave the stone with a natural, or colour-enhanced appearance, but always with the stone surface exposed.

Why this type of sealant is used:

Because 99% of natural stone is porous, this sealant is essentially designed to stop any spillages onto the stone penetrating the internal structure of the tile and causing damage or a deep set stain. There is a video on our YouTube channel which demonstrates the difference between water poured onto a sealed and an unsealed marble surface.

What it means in practice:

Accidents happen. Our clients have split everything from coffee machine descaler to limescale remover on their natural stone and it is always restorable. When stone has been properly sealed, the damage is usually only surface level. Take a look at our portfolio pages to see this in action.

Surface sealants form a physical barrier between the stone and the environment. Modern sealants are either wax or polymer-based, which can achieve matt, satin or gloss finishes to the stone. Such sealants however cannot be applied outdoors or in wet areas as they are affected by moisture. They are also ineffective if applied to a polished surface as they cannot penetrate the surface sufficiently to bond.

Why this type of sealant is used:

Surface sealants are usually used to create a shine to a tile that would otherwise be very dull. Riven slate, pillow edged limestone, tumbled travertine and other textured surfaces will be naturally matt finish. The texture and unevenness don’t allow these finishes to be polished mechanically, so a topical sealant is required if a satin or glossy sheen are required.

In other situations, such as terracotta, a surface sealant will also act to bind and consolidate a rough textured finish. This will mitigate the potential for the surface to flake apart or create dust by breaking down.

What it means in practice:

In practice, aside from the aesthetic changes these sealants can provide, apply them to textured stones will give another line of protection to staining. Rough textured and matt finish stone will be naturally more porous than honed and polished finishes. Applying a surface sealant on top of an impregnating sealant will provide a ‘sacrificial layer’. Any chemical spills will react with this sealant rather than the surface of the stone.

How long will the sealant or impregnator last?

Contrary to popular belief, impregnating sealants themselves don’t degrade naturally over time. The pores and capillaries that were originally sealed will remain so. However, abrasion caused by foot-traffic will create and expose new pores and capillaries which will require additional sealant. Usually, the more people or pets in the property the more frequently the protection will need to be reapplied.

Impregnating sealants can also be denatured by high alkaline or acidic liquids. Chemical spills can cause damage to a stone surface but also render the previously applied sealant to become ineffective. This is why it is worth having the stone restored and resealed as soon as possible after a spillage has occurred. The damage from the initial accident won’t worsen but the exposed stone will be more vulnerable as a result.

Surface sealants on the other hand are designed to be a sacrificial layer. They aim to protect the stone surface from the external environment. This means that liquid spillages and abrasion will impact the sealant and not the stone surface. These sealants will also be impacted by repeated cleaning regimes. Over time, you can expect this sealant to degrade and it will need to be reapplied in order to keep the stone safe from internal damage and maintain the level of shine that they provide.

Looking after your natural stone sealant

It is almost more important to look after the sealant as it is your stone – the two go hand in hand. Our Athena Aftercare guide, is designed to provide your clients with best practice when it comes to maintaining their stone. Following this guidance will ensure that the sealant can continue to do its job to protect any natural stone surface. For a PDF copy email [email protected]

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