Professional Advice: Choosing Natural Stone

Caring for Natural Stone

Protecting Porous Stone


So, what materials are porous and why should they be protected? And, how can builders capitalise on it?

Stone, brick, concrete, paving, tiles and grout are all porous, having millions of interconnected capillaries (microscopic veins) running though them. Porous materials act something like a hard sponge and actually suck liquids in.

This is capillary suction at work – with enough power to suck the liquid up the tube, against gravity.

Even dense materials such as granite or terracotta will absorb an oil or water-based liquid when it is in contact with the surface for long enough.

Common Types of Damage

Staining – from oil or water-based substances which penetrate below the surface of the material.

Salt attack – efflorescence and spalling are common types of salt attack which are expensive or impossible to fix. Efflorescence is the unsightly white residue on the surface of stone. Salt, dissolved in the water, is absorbed up through the material and turns into tough calcium carbonate residue on contact with air on the surface.

Sealing for Lasting Protection

There are 3 main types of sealer - topical (surface) sealers, penetrating sealers and impregnating sealers.


Topical Sealers

Topical sealers generally acrylic or polyurethane based. Like wood varnish, they form a coating over the surface, and tend to be cheaper than penetrating sealers, but have disadvantages - Imagine a plastic film over a floor.

Topical sealers are likely to noticeably change the appearance and slip resistance of the surface, lock in moisture and wear relatively quickly. When they wear through, the entire surface has to be stripped and resealed.

Penetrating Sealers

Penetrating sealers generally longer lasting than topical sealers, but vary in performance. Many penetrating sealers use fluorocarbons (e.g. Teflon) or silicone, can work well and are somewhat breathable. Penetrating sealers still have a limited lifespan in comparison with the surfaces they are meant to protect, and to keep performing, the working molecules may need to be ‘topped up’ by the use of special cleaners.

Impregnating Sealers

Impregnating sealers are generally the longest lasting, fully breathable – allowing water vapor to escape and provide the best protection without substantially altering the natural look or slip resistance of the surface.

The world-leading sealers in this category have been developed in Australia by Dry-Treat Pty Ltd, with extensive warranties up to 30 years. Dry-Treat impregnating sealers have been used to protect Australian icons such as the Opera House, National Police Memorial, MCG and Hay St Mall in Perth, and are specified by the NSW RTA as well as councils, engineers and developers across Australia and more than 30 other countries.


  • Protects against oil and water-based staining, damage and salt attack (e.g. efflorescence).
  • 15 Year Performance Warranty can be issued, if sealer is applied by Dry-Treat Accredited Applicator.
  • Protects against oil and water-based stains (from foodstuffs etc) and salt damage (e.g. efflorescence).
  • Low cost and easy to maintain – does not require the use of special cleaners or cleaning methods.
  • Slip resistance is hardly altered, as it is not a surface sealer, but works from within.


  • Hard, porous building materials (brick, conrete, natural stone, tiles, pavers) act like sponges, actually sucking liquids into the pores.
  • Dry-Treat impregnating sealers deeply penetrate the material with special molecules which bond inside the pores. These molecules change the forces at work so liquids are repelled instead of being drawn into the material.
  • Dry-Treat Pty Ltd is an Australian company leading the world in sealing technology.

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Natural Stone History & Trivia