Caring for Natural Stone
PROTECTING POROUS BUILDING MATERIALS
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.
We've published a number of articles about caring for your natural stone. Here are a few things you should never do!
Don't do this!
1) Don't stand on your countertops. You can cause cracks in the stone, especially at the sink or range areas.
2) Don't slide sharp or abrasive objects on the stones surface and always have felt pads under abrasive objects when possible. Crock pots and some kiln fired cookware are abrasive enough to scratch the hardest of granites. Using place mats or padding will help prevent scratches.
3) Don't use kitchen granite as a cutting board. Knives will dull quickly and scratches may occur.
4) Don't allow acidic foods or liquids to come in contact with stones that contain calcium, such as marble, limestone or travertine. These stones may show damage by the etching of the stones surface. Polished stones will show more etch damage than on a honed finish.
5) Don't forget to have walk-off mats at all stone entries to help keep abrasives from scratching floors.
6) Don't have a marble, limestone or travertine floor re-polished with crystallizers. This method is also called re-crystallization, and is considered to cause long term damage by most Natural Stone Restoration Professionals.
Here are a few common problems caused when people incorrectly care for their natural stone. The good news? All these problems can be repaired!
1. A cleaning person that used a well known glass cleaner and it was spilled on the marble floor that was in the bathroom and the marble vanity top as well.
This common glass cleaner contained vinegar which is acidic and it burned or etched the stones finish.
2.The builder that didn’t cover to protect a very expensive natural stone floor during the construction process suffers as other contractors saw that tools from the other trades were placed on the unprotected floor and did the same. Also there was no walk off-mats at any of the entries.
The floor was scratched, paint stained and acid etched.
3. The home owner had let the granite countertops be use as a very expensive step ladder to change the recessed light bulbs.
Cracks developed at the sink and where the drop-in stove top cut outs were.
Lichen, algae, mold and tannins from trees that stain headstones are considered biological contaminants. Lichens roots secrete acid that will dissolve the calcium in marble and limestone. Algae, mold and lichen grow because the stone pores absorb water. Moisture in the stone during the winter months will freeze and thaw causing spalling (surface loosening of minerals and cracking).
Tannins stains are caused from leaves, nuts and bark that have fallen from trees. Headstones can be cleaned with common household ingredients that most of us have (ammonia, liquid dish soap and bleach used separately)……. Note: That this is not what natural stone restoration professionals would use, but, the cost of “not” hiring them may lead to further damage, so this home remedy will help your monument to a love one’s life, live for future generations to come.
Step #1 Soak the stone with clean water with pump sprayer, keeping stone moist for 10-20 min.