Natural stone is one of the most beautiful flooring materials available for both indoor and outdoor applications. Travertine, sandstone, slate, limestone, and granite all bring a warmth and character to a space that manufactured tiles work hard to replicate. But natural stone comes with a responsibility that porcelain and ceramic tiles do not: it needs to be sealed, and that sealing needs to be maintained over time.
Understanding how sealing works, which sealer to use, when to apply it, and how to maintain sealed stone makes the difference between a natural stone surface that looks spectacular for decades and one that stains, etches, and deteriorates within the first few years.
Iconic Tiles’ natural stone range includes travertine, crazy paving, dry stone walling, and more. This guide covers everything you need to know to look after natural stone correctly.
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Why Natural Stone Needs to Be Sealed
Natural stone is a porous material. Unlike porcelain, which is fired at very high temperature to create a dense, near-impermeable surface, natural stones including travertine, sandstone, limestone, and marble all have a network of microscopic pores within their structure. Those pores allow water, oils, and other liquids to penetrate the stone surface if it is not protected.
The consequences of leaving natural stone unsealed include:
- Staining from food, wine, oils, and garden materials that penetrate the pores and discolour the stone
- Water damage and efflorescence (white salt deposits) as moisture moves through the stone and evaporates from the surface
- Biological growth: algae, mould, and moss establishing in the pores of outdoor stone in damp or shaded conditions
- Frost damage in areas subject to overnight frost, where water freezes within the stone and causes spalling
- Difficulty cleaning, as oil and other penetrating contaminants in an unsealed surface cannot be removed from the pores
A quality sealer fills or partially fills the pore structure of the stone, creating a barrier that keeps liquids from penetrating while allowing the stone to breathe. The stone remains natural-looking, but its vulnerability to staining and water penetration is dramatically reduced.
Types of Natural Stone Sealers
Understanding the two primary sealer categories is essential before purchasing a product.
Penetrating (impregnating) sealers
Penetrating sealers, also called impregnating sealers, work below the surface of the stone. The sealer molecules enter the pores of the stone and partially fill them, creating a hydrophobic (water-repelling) and oleophobic (oil-repelling) barrier without building a film on the stone’s surface.
The key characteristics of penetrating sealers:
- They do not change the visual appearance of the stone, or change it minimally (some formulations are available as ‘natural look’, ‘colour-enhancing’, or ‘wet look’ options)
- They allow the stone to breathe, which prevents moisture vapour from becoming trapped and causing efflorescence or delamination
- They do not flake, peel, or crack because they are below the surface, not a surface coating
- They need periodic reapplication as the molecules eventually deplete over time
Penetrating sealers are the recommended choice for most natural stone applications, both indoor and outdoor, and are particularly important for outdoor applications where UV exposure and weather would degrade a surface sealer rapidly.
Topical (surface) sealers
Topical sealers create a protective film on the surface of the stone rather than penetrating into it. They can provide a satin, gloss, or high-gloss sheen to the stone and provide very visible protection against surface contamination.
Their limitations for outdoor use are significant:
- They are vulnerable to UV degradation outdoors and may yellow, haze, or peel when exposed to Sydney’s intense sun
- They can become slippery when wet, which is a serious safety concern for outdoor applications
- If moisture is present below the stone, it can become trapped under a topical sealer and cause the sealer to delaminate or the stone to effloresce
Topical sealers are occasionally appropriate for specific indoor applications. For most outdoor natural stone in Sydney, a penetrating impregnating sealer is the correct choice.
| 💡 Colour-enhancing sealers: If you want to deepen and enrich the natural colour of your stone (bringing out the warmth in travertine or the depth in sandstone), a penetrating sealer with a colour-enhancing formulation achieves this without a surface film. Apply to a small, inconspicuous test area first to confirm you are happy with the colour shift before treating the full surface. |
How to Seal Natural Stone: Step by Step
- Clean the stone thoroughly: before sealing, the stone surface must be completely clean. Any existing stains, grout haze, efflorescence, or biological growth must be addressed first with appropriate stone-safe cleaning products. Sealing over a contaminated surface locks the contamination into the stone.
- Allow the stone to dry completely: the stone must be fully dry before sealer is applied. Moisture within the stone can prevent penetrating sealer from entering the pores correctly. For outdoor stone, wait a minimum of 24 to 48 hours of dry weather after any rain before sealing. For newly installed stone, wait until the adhesive and grout have fully cured (typically at least 28 days for mortared outdoor installations)
- Test the sealer on an inconspicuous area: apply the sealer to a small hidden area first to confirm the finish (colour-enhancing effect, sheen level) is what you expect before treating the full surface
- Apply the sealer with a brush, roller, or applicator pad: apply evenly following the manufacturer’s instructions for application rate. Do not apply so thickly that the sealer pools on the surface
- Allow initial penetration time: the sealer needs time to penetrate into the stone. This period varies by product but is typically 5 to 15 minutes. During this time, keep the surface wet by brushing in additional sealer if it is absorbing quickly
- Wipe off excess sealer: before the sealer fully cures, wipe off any excess that has not been absorbed by the stone. Sealer that is not absorbed will dry as a hazy, sticky residue on the surface that is difficult to remove. This is one of the most common sealing mistakes
- Apply a second coat: most penetrating sealer applications benefit from a second coat after the first has partially cured (follow manufacturer timing, typically 2 to 4 hours). The second coat fills any pores not fully addressed by the first
- Allow full cure time before use: do not allow traffic, water, or any other contact with the surface until the sealer has fully cured. This is typically 24 hours for foot traffic and up to 72 hours for full cure, though individual products vary
| ⚠️ Sealing before grouting: For natural stone tiles, apply the first coat of sealer before grouting, not after. Sealing the stone first protects the tile surface from grout haze penetrating the pores during the grouting process. After grouting and cleaning, apply the final sealer coat to both the stone and the grout lines. |
How Often to Reseal Natural Stone
The resealing frequency for natural stone depends on the location, the exposure conditions, and the quality of the sealer used. General guidelines:
| Location and application |
Suggested resealing frequency |
| Outdoor pool surround (constant water exposure) |
Every 1 to 1.5 years |
| Uncovered outdoor entertaining area |
Every 1 to 2 years |
| Covered outdoor alfresco (occasional rain exposure) |
Every 2 to 3 years |
| Indoor natural stone floor (high traffic) |
Every 2 to 3 years |
| Indoor natural stone floor (low traffic) |
Every 3 to 5 years |
| Indoor feature wall (no traffic or water) |
Every 5+ years or as needed |
These are general guides. The water droplet test is the most reliable way to determine whether resealing is needed: apply a few drops of water to the stone surface. If the water beads on the surface, the sealer is still active. If the water soaks into the stone within a few seconds, the sealer needs refreshing.
Daily and Ongoing Maintenance for Natural Stone
Sealing is not a substitute for regular maintenance. A well-sealed stone surface is still vulnerable to physical abrasion, surface etching from acidic substances, and accumulated surface dirt that dulls the appearance over time.
Regular cleaning
Natural stone should be swept or vacuumed regularly to remove grit and particles that can scratch the surface under foot traffic. Damp mopping with a neutral pH stone-safe cleaner is appropriate for regular cleaning. Do not use:
- Acidic cleaners (vinegar, citrus-based products, or products containing hydrochloric acid) which will etch calcium-based stones including travertine, marble, and limestone
- Bleach or ammonia-based cleaners which can strip sealers and affect the stone over time
- Abrasive scouring products which will scratch polished or honed stone surfaces
- Steam cleaning at high temperatures which can damage some sealers and cause thermal shock in some stone types
Dealing with spills
The most important rule for spills on natural stone is speed. Even sealed stone is not impervious, and prolonged contact with wine, oil, coffee, or acidic liquids will eventually penetrate or etch the surface. Blot (do not wipe) spills immediately and clean the area with a neutral stone cleaner.
Outdoor stone
Outdoor
travertine and
crazy paving benefit from periodic hosing to remove surface dirt, leaf stains, and biological material. In shaded or damp areas, a diluted stone-safe cleaner can be used to address algae or moss growth. Pressure washing at moderate pressure (not the maximum setting) can be used for periodic deep cleaning of outdoor stone, but avoid directing the pressure washer at the grout joints at close range as this can erode the grout over time.
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Natural Stone for Sydney Homes
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Frequently Asked Questions
