Our stone maintenance services and process differ, depending on the type of stone or other surface and its location. The most common types of indoor surfaces we clean, refinish, and seal are travertine, marble, slate, and granite. Flagstone is the most common type of stone used in outdoor patios, decks, and outdoor features.
The term “Flagstone” actually refers to the cut of the stone, not the type of stone. Flagstone is almost always a Sandstone. Flagstone refers to the cuts and the installation with large irregular shaped pieces of stone and large grout lines. Any stones can be cut and installed as a Flagstone pattern.
Sandstone is a sedimentary stone that is deposited as mountains are turned into sand grains by erosion. After time, the sand grains are compacted together and bonded together by minerals to form a solid rock.
Flagstone and Spalling
Flagstone is very susceptible to erosion and spalling.
What is Spalling?
Spalling is the erosion process that occurs when the bonding molecules that hold the sand particles together fail, and the natural stone (like sandstone) starts to peel off in layers. The level of spalling can range from e a fine grain of sand to small pebbles breaking off.
If the stone is treated with a sealer, spalling might never occur. Once spalling occurs (and it will if the sandstone is exposed to the elements) there is permanent damage that could have been avoided or delayed for decades instead of occurring in years.
Can Spalling Damage on Natural Stone be Stopped?
Yes. A thick, expoxy-based densifying consolidator like TSSPRO-600 can stabilize the surface and prevent further damage from occurring. Once the densifier is cured, we recommend a layer of professional grade sealant as well.
Cleaning & Sealing Process
- Stripping Old Sealant
- Stain Removal
- Calcium Efflorescence Removal
- Mold & Mildew Removal
- Soda Blasting
- Chemical Cleansing
- Densifying Consolidators
- Sealant Application
Our Flagstone cleaning process is very aggressive. We use a chemical cleaner with a surface cleaner and hot water to remove oils, dirt and any loose stone. We then inspect the surface for layers that are peeling off and need to be removed before the sealer can be applied.
The cleaning process may also involve stripping old sealant. Don’t trust just anyone for this, you need professional that can safely strip old flagstone sealant without damaging the vulnerable stone.
Once all the loose debris has been removed and the stone is dry we then soak the stone with as much sealer as it will absorb. We apply an ample amount of sealant, or as much sealant is necessary to seal each particular type of stone and we stand behind our written guarantee. We perform a manual compound acid scrub that consolidates and clarifies the sanding and stone.
Flagstone installed as coping on pools, especially saltwater pools, should always be sealed. The right coping sealer will protect from chlorine, saltwater penetration and stains. Sealers are not bulletproof and once a sealer is applied it needs to be maintained regularly. It will generally need to be applied every 5-7 years depending on the condition of the stone when first applied.
Special note: Drying times – Depending on humidity and average daytime temperatures the sealer should be fully cured prior to water contacting the surface. Full cure is generally achieved in 72 hours. If there is a possibility of rain within the 72 hour cure time, we cover the surface so it will remain dry. However, in Texas with the temperature above 90 degrees drying time can be achieved in much less time.
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