Why Should Natural Stone Be Sealed?

Simply put: to retain the beauty, preserve the life, and keep it maintainable. No one asks why you should paint your house. It is common knowledge if you didn't the wood, stucco, metal or other materials would absorb, stain, discolor, rust and erode. Natural stone is no different. Staining, discoloration, erosion and odor absorption are all typical adversities that happen to stone if not sealed. As stone wears, abrasions damage the finish by opening up pores and exposing the stone to problems. All natural stone is porous and what it absorbs effects it. Even the chemicals found in "tap water" (chlorine, minerals, salts, etc.) can cause trouble to the stones' substrate. Moreover, decorative stones are being used for their beauty in high traffic areas where design precedes function. Sealing and maintenance are critical for preserving these delicate installations as well as any natural stone where absorption of any kind is possible.

What Does The Sealer Do?

Impregnating / Penetrating sealers retard the absorption of liquids that may cause staining, odor and erosion beneath the surface. The word "sealer" is really a misnomer. Proper sealers allow microscopic ventilation of temperature, air and moisture (known as vapor). For most installations impregnating sealer applied to the surface soaks in approximately 1/8"-1/4". The water or solvent that carries the "sealing resins" evaporates. The remaining resins (silicone or Teflon like materials) coat the pores with a repelling layer. This impedes absorption of water, oil & dirt, but allows the stone to breathe. This "vapor transmission" is essential for the life of the stone. When vapor is not allowed to transfer, it creates its own escape path causing fractures (cracks), spalling (splitting within the substrate) and erosion. It is important to use a premium grade, impregnating "stone" sealer to insure proper protection and vapor transfer.

What The Sealer Does Not Do!

1 - Sealers do not prevent surface pitting, scratches, abrasion or etching. Foot traffic, sharp objects or acidic agents effect the stone surface. Sealers protect below the surface. Routine honing or polishing and hole filling are necessary for surface renewal.
2 - Impregnating sealer is not a water or stain proof barrier. It will allow time for cleanup of accidental mishaps. However, if liquids are left for long periods of time staining may occur. Most sealers do resist oil, however; hot cooking oils or grease may melt the sealing resins and stain. Oils should be removed immediately.
3 - You cannot waterproof showers, decks or grout with stone sealers. Waterproofing is a membrane that should be applied prior to installation.
4 - Sealers do not keep dirt off stone or out of grout. But they do make them easier to clean. A simple scrub and then removal of dirty water will clean most soiled areas.
5 - Impregnating Sealers do not make the stone "shiny". If they do, it's the wrong kind of sealer. Topical sealers are for interior slate or other clefted stones and are not suitable for smooth stone applications.

What Kind Of Sealer Should Be Used?

This depends on the type of stone, location, design and use. A top grade impregnating sealer can be used on all stone installations. It displays the "natural" look and is ideal for the majority of applications. For clefted or rough interior installations a topical acrylic sealer may be more favorable. Acrylics, after multiple coats, provide a protective coating on the surface which usually deepens color and displays a higher sheen. Like going from flat wall paint to semi-gloss, the surfaces become far easier to clean. It should be noted that showers and exterior installations are not suitable for topical sealers. They can peal, flake and trap moisture. Acrylics are also not suitable for smooth surfaced stones. It is like putting paint on glass. Acrylics do not bond well to smooth textures and therefore scuff, scratch and peel in a very short time. In some cases where greater color is needed ENHANCER SEALERS may work. ENHANCERS are made with "wetter" silicon, which displays a deeper color. They do dry and dissipate sooner then standard impregnating sealer so resealing will need to be more frequent.

How Often Should Resealing Be Done?

Sealers do not last forever. Father Time, Mother Nature, cleaning, accidents and wear & tear all impact sealers. Resins in impregnators break down, and acrylics wear thin. Resealing is determined by traffic, stone porosity and sealer quality. For most active homes, sealed with a good sealer, every-other-year in high traffic and wet areas is sufficient. When re-surface maintenance is done, areas that absorb should be resealed. Exterior applications will have a fluctuating sealer life depending on climate and maintenance. CONSULT OUR STONE CARE PROFESSIONALS.

How Do You Know Your Stone Was Cleaned and Sealed Properly?

You can't always tell by looking. Appearances can be deceiving. Many stones have rustic, old-world finishes, which appear ragged and worn by design. Cleaning and sealing does not change their appearance. If desired, re-honing or polishing upgrades can offer a more consistent finish to alter the appearance. However, improper procedures or using the wrong type of sealer can adversely effect the stone finish. Topical sealers or enhancers are often misapplied to smooth stones leaving blotchy, cloudy areas where scuffing and tracking can easily occur. If the stone has a rough surface, aggressive cleaning is necessary, otherwise haze and debris can remain on the stone. A visit from a qualified stone care professional is often needed to determine a diagnosis.

How Do You Know If The Surfaces Are Sealed?

A good way to test sealer is to apply water to the stone and grout. Let the water stand for five minutes and see how the stone and grout react. Stone & grout darken deeply when moisture absorbs. If the water beads it is an indication the surface was recently sealed. The beading affect will not last over time. Resins near the surface wear and wash away with limited use. Just because water is not beading does not mean the surfaces are not well sealed. Remember that sealers protect the inside of the stone. Slight darkening may occur, but will dissipate in a short time.

My Travertine Floor Is Getting Holes In It, Do I have Bad Stone?

No. Travertine is formed in springs where water and gases pass through it. There are air bubbles, cavities, voids, holes and soft pockets all through the stone. Exposing these holes in high traffic areas, especially under chairs is common. Holes can be filled with a number of different compounds depending on the type of travertine. It is part of maintenance.

My Stone Is Sealed But I'm Getting Dull Spots That Look Like Watermarks. What's Wrong?

Anything acidic etches the surface of marble, travertine and limestone. These dull, hazy, white looking marks are actually etches from foods, liquids, cleaners or other products containing acid. Etching can happen instantly. Like when lemon juice hits your eye and burns, the stone shows it just as quickly. Only routine polishing or honing can remove these spots. See the stone care section for some hints to minimize acid etching.

Why Seal Outside Stone?

To prolong the life of the installation. Areas especially exposed to the elements need to be sealed to retard natural erosion. In nature, mountains and rock erode primarily through the absorption and evaporation of water. Mother earth sliced into thin layers does not have the structure depth to handle much erosion. Therefore, sealing the stone's surface hinders the deep absorption of water, greatly slowing the erosion process. Sealing also offers better stain resistance and ease of maintenance. We recommend exterior stone to be treated periodically depending on weather exposure and the amount of water use on the stone.