Care & Maintenance
The natural stone you have in your home, office, or commercial building is an investment that will give you many years of alluring service.
Simple care and maintenance will help preserve your natural stone’s beauty for generations to come.
There are three primary natural stone finishes:
Many other finishes are available and used throughout the world. Consult with a natural stone professional if your finish does not match these three primary types.
Know Your Natural Stone
Natural stone can be classified into two general categories according to its composition: siliceous stone or calcareous stone. Knowing the difference is critical when selecting cleaning products.
Siliceous stone is composed mainly of silica or quartz-like particles. It tends to be very durable and relatively easy to clean with mild acidic cleaning solutions. Types of siliceous stone include: granite, slate, sandstone, quartzite, brownstone, and bluestone.
Calcareous stone is composed mainly of calcium carbonate. It is sensitive to acidic cleaning products and frequently requires different cleaning procedures than siliceous stone. Types of calcareous stone include: marble, travertine, limestone, and onyx. What may work on siliceous stone may not be suitable on calcareous surfaces. BigAppleMarble.com products are calcareous stone.
What Type of Natural Stone Is It?
It is advisable to maintain careful records about the type, name, and origin of the stone existing in your building. If such records do not exist, you should explore the following options before determining a cleaning and maintenance program:
- Consult with a professional natural stone supplier, installer, or a restoration specialist to help identify whether your stone is siliceous or calcareous.
- Conduct a visual identification of the natural stone. While there are exceptions, the following characteristics are common:
- Granites have a distinct crystal pattern or small flecks; very little veining.
- Limestones are widely used as a building stone. Colors are typically gray, tan, or buff. A distinguishing characteristic of many limestones is the presence of shell and/or fossil impressions.
- Marbles are usually veined, fine-textured materials that come in virtually unlimited color selections.
- Sandstones vary widely in color due to different minerals and clays found in the stone. Sandstone is light gray to yellow or red.
- Slates are dark green, black, gray, dark red, or multi-colored. They are most commonly used as a flooring material and for roof tiles and are often distinguished by distinct cleft texture. Some notable cladding projects have also included slate.
- Conduct a simple acid sensitivity test to determine if your natural stone is siliceous or calcareous. You will need:
- 4 ounces of a 10% solution of muriatic acid or household vinegar
Because the test may permanently etch the stone, select an out-of-the-way area (a corner or closet) several inches away from any mortar joint. Apply a few drops of the acid solution to the stone surface on an area about the size of a quarter. Two possible reactions will occur:
- Acid drops will bubble or fizz vigorously – a sign that the natural stone is calcareous.
- Little or no reaction occurs – stone can be considered siliceous. See note below.
Rinse the area thoroughly with clean water and wipe dry.
NOTE: This test may not be effective if surface sealers or liquid polishes have been applied. If an old sealer is present, chip a small piece of the stone away and apply the acid solution to the fractured surface.
CAUTION: Muriatic acid is corrosive and is considered to be a hazardous substance. Proper head and body protection is necessary when acid is used. Again, it is always wise to consult with a natural stone professional if you are unable to visually identify the stone and/or are uncomfortable using the acid test.
Defining the Natural Stone’s Current Condition
- Are the tiles flat and even?
- Are there any cracked tiles?
- What type of stone finish exists?
- Has the stone been coated with any waxes, acrylics, enhancers, or other coatings? If so, which type and manufacturer?
- Is there any evidence of staining? What type?
- If the natural stone has been sealed with a topical sealer, are there any signs that the sealer has worn off?
- Uneven tiles (a sign of lippage) may result in the floor needing to be ground flat, honed, and then polished.
- Cracked tiles will allow dirt and other debris to accumulate in the cracks. This may require that the tiles be replaced, or at a minimum, filled.
- Knowing the type of stain (organic, oil-based, etc.) will help identify the proper stain removal technique needed. Also, the level of stains or spills the natural stone can be exposed to will play a role in determining if an application of a sealer is appropriate.
Flooring Surfaces: Many flooring surfaces can become slippery when wet. When wet conditions occur, reduce potential hazards by doing the following:
- Spread carpeted runners from each outside door into lobbies and corridors to help dry shoe soles.
- Place bright-colored “slippery when wet” pylons on walking surfaces in conspicuous places.
- Mop or shovel walking surfaces as often as necessary to remove standing water, ice, and/or snow.
- Issue standard instructions to building maintenance personnel and prominently post at all janitorial workstations.
- Follow local building and safety codes.
General Guidelines for Stain Removal
- Remove any loose debris.
- Blot spills; wiping the area will spread the spill.
- Flush the area with plain water and mild soap and rinse several times.
- Dry the area thoroughly with a soft cloth.
- Repeat as necessary.
- If the stain remains, refer to the section in this guide on stain removal.
- If the stain persists or for problems that appear too difficult to treat, call your stone care professional, installer, or restoration specialist.
Do clean surfaces with mild detergent or stone soap.
Do thoroughly rinse and dry the surface with clean, clear water after washing.
Do blot up spills immediately.
Do protect floor surfaces with non-slip mats or area rugs and countertop surfaces with coasters, trivets, or placemats.
Don’t use vinegar, lemon juice, or other cleaners containing acids on marble, limestone, travertine, or onyx surfaces.
Don’t use cleaners that contain acid such as bathroom cleaners, grout cleaners, or tub & tile cleaners.
Don’t use abrasive cleaners such as dry cleansers or soft cleansers.
Don’t mix bleach and ammonia; this combination creates a toxic and lethal gas.
Don’t ever mix chemicals together unless directions specifically instruct you to do so.
Don’t use vacuum cleaners that are worn. The metal or plastic attachments or the wheels may scratch the stone’s surface.
Several factors must be considered prior to determining if the natural stone should be sealed:
- What is the hardness, density, and durability of the stone?
- How porous is the natural stone and how fast will it absorb a liquid (also referred to as the absorption coefficient)?
- Is the natural stone expected to be in frequent contact with a staining agent?
- What type of finish was applied to the surface? For example, a polished surface is more resistant to staining than a honed surface.
- Will the sealant affect the color or other aesthetics of the stone?
- If a resin was applied to the natural stone, how will the sealant react with the resin?
- Where is the natural stone located (e.g. countertop, floor, wall, foyer, bathroom, etc.)? Residential or commercial?
- What type of maintenance program has the stone been subjected to?
The type of the natural stone, its finish, its location, and how it is maintained all need to be considered when determining how to protect the stone.
In some cases it makes sense to seal the natural stone. Once properly sealed, the stone will be protected against everyday dirt and spills. In other cases, it is best to leave the stone untreated. Topical sealers can alter the surface texture and finish as well as build up on the surface, creating a layer that is less durable than the stone. Generally, topical sealers are not recommended in exterior applications because they can trap moisture within the top layer of the stone, which may lead to surface deterioration during freeze/thaw cycles.
If you have decided to treat your natural stone, make sure you understand the differences between the types of sealers available on the market:
Topical Sealers are coatings (film formers) designed to protect the surface of the natural stone against water, oil, and other contaminants. They are formulated from natural wax, acrylic, and other plastic compounds. When a topical sealer is applied, the maintenance program often shifts from a program focused on stone care to a program focused on the maintenance of the sealer (for example: stripping and reapplication).
Impregnators are water - or solvent- based solutions that penetrate below the surface and become repellents. They are generally hydrophobic (water-repelling), but are also oleophobic (oil-repelling). Impregnators keep contaminants out, but do not stop the interior moisture
from escaping. These products are considered “breathable,” meaning they have vapor transmission.
Vanity tops and food preparation areas may need to have an impregnator applied. Check with your installer for recommendations. If an impregnator is applied, be sure that it is safe for use on food preparation surfaces. If there are questions, check with the product manufacturer.
Before sealing, always:
- Read the Manufacturers Warranty and Instructions.
- Contact the manufacturer prior to application if you are unsure or need clarification. The wood-working analogy of ‘measure twice, cut once’ applies.
- Don’t switch from one product to another without fully understanding any potential issues. Not all products are alike – again, consult with the manufacturers.
- Consult with your stone professional as necessary.
- Ask yourself, does the natural stone need to be treated in the first place?
Daily Cleaning Procedures and Recommendations
Clean natural stone surfaces with a few drops of neutral cleaner, stone soap (available at hardware stores), or a mild liquid dishwashing detergent and warm water. Use a clean soft cloth for best results. Too much cleaner or soap may leave a film and cause streaks. Do not use products that contain lemon, vinegar, or other acids on marble or limestone. Rinse the surface thoroughly after washing with the soap solution and dry with a soft cloth. Do not use scouring powders or creams; these products contain abrasives that may scratch the surface.
Dust mop interior floors frequently using a clean, non-treated dry dust mop. Sand, dirt, and grit do the most damage to natural stone surfaces due to their abrasiveness. Mats or area rugs inside and outside an entrance will help to minimize the sand, dirt, and grit that will scratch the stone floor. Be sure that the underside of the mat or rug is a non-slip surface.
Normally, it will take a person about eight steps on a floor surface to remove sand or dirt from the bottom of their shoes.
Normal maintenance involves periodic washing with clean, potable water and neutral (pH 7) cleaners. Soapless cleaners are preferred because they minimize streaks and film. Mild, phosphate-free, biodegradable liquid dishwashing soaps or powders or stone soaps are acceptable if rinsing is thorough.
Wet the stone surface with clean water. Using the cleaning solution, wash in small, overlapping sweeps. Work from the bottom up if it is a vertical surface. Rinse thoroughly with clean, potable water to remove all traces of soap or cleaner solution. Change the water in the rinse pail frequently. Dry with soft cloth and allow to thoroughly air dry.
Bathroom and Other Wet Areas:
Soap scum can be minimized by using a squeegee after each use. To remove soap scum, use a non-acidic soap scum remover or a solution of ammonia and water (about ½ cup ammonia to a gallon of water). Frequent or over-use of an ammonia solution may eventually dull the surface of the natural stone.
Outdoor Pool and Patio Areas:
In outdoor pool, patio, or hot tub areas, flush with clear water and use a mild bleach solution to remove algae or moss.
Exterior Stone Maintenance:
The large expanses of the natural stone generally found on exterior applications may make it impractical to perform normal maintenance on a frequent basis. Large installations, however, should be given periodic overall cleaning as necessary to remove accumulated pollutants. Easily accessible natural stone surfaces such as steps, walkways, fountains, etc., should be kept free of debris and soiling by periodically sweeping and washing with water.
Normal maintenance should include periodic inspection of stone surfaces for structural defects, movement, deterioration, or staining.
Water penetrating exterior wall cavities through defective flashing or unsealed joints can cause efflorescence, a mineral salt residue left on the surface of masonry when water evaporates. In addition, condensation in wall cavities prevented from reaching the exterior surface because of blocked weep holes can dislodge masonry in a freeze-thaw climate. Look for a darkening affect of the stone.
It is recommended that you contact your natural stone professional for a remedy.
Moisture coming up through a floor slab seeks the easiest possible pathway to evaporate into the atmosphere. Often, the veining or micro-cracks in the structures of some stones provide that path. The moisture dissolves all the salts from the ground, the substrate, and the stone, carries them to the surface, and deposits them as the moisture evaporates, giving the appearance of a faulty natural stone.
Paint Stains: Small amounts can be removed with lacquer thinner or scraped off carefully with a razor blade. Heavy paint coverage should be removed with a commercial liquid paint stripper.
DO NOT USE ACIDS OR FLAME TOOLS TO STRIP PAINT FROM STONE.
Water Spots and Rings (surface accumulation of hard water): Buff with dry 0000 steel wool.
Fire and Smoke Damage: Older stones and smoke - or fire-stained fire - places may require a thorough cleaning to restore their original appearance. Commercially available smoke removal products may save time and effort.
Etch Marks (calcareous stones): Caused by acids (typically from milk, fruit juices, alcohol, etc.) left on the surface of the natural stone, some will etch the finish but not leave a stain; others will both etch and stain. Once the stain has been removed, wet the surface with clear water and sprinkle with marble polishing powder. Rub the powder into the stone with a damp cloth or by using a buffing pad with a low-speed power drill or polisher. Continue buffing until the etch mark disappears and the marble surface shines. Honing may be required for deep etching. This process may require the services of a natural stone maintenance professional.
Efflorescence: A white powder that may appear on the surface of the stone, it is caused by water carrying mineral salts from below the surface of the natural stone to the surface and evaporating. When the water evaporates, it leaves the powdery salt residue. If the installation is new, dust mop or vacuum the powder. Repeat as necessary as the stone dries out. Do not use water to remove the powder (adding water will only add to the problem).
If the problem persists, contact the natural stone contractor to identify and remove the cause of the moisture.
Using Stain-Removing Poultices
Poultice materials include kaolin, fuller's earth, whiting, diatomaceous earth, powdered chalk, white molding plaster, and talc. Approximately one pound of prepared poultice material will cover one square foot. Do not use whiting or iron-type clays such as fuller's earth with acid chemicals; the reaction will cancel the effect of the poultice. A poultice can also be prepared using white cotton balls, white paper towels, or gauze pads. Premixed poultices that require adding only water are also available from stone maintenance supply companies.
Preparing & Applying the Poultice:
- Prepare the poultice. If using powder, mix the cleaning agent or chemical to a thick paste the consistency of peanut butter. If using paper, soak the chemical and let drain. Don’t let the liquid drip.
- Prepare the stain area. Wet the stained area with distilled water.
- Apply the poultice to the stained area about ¼” to ½” thick and extend the poultice beyond the stained area by about one inch. Use a wood or plastic spatula or scraper to spread the poultice evenly.
- Cover the poultice with plastic and tape the edges to seal it.
- Allow the poultice to dry thoroughly, usually about 24 to 48 hours. The drying process is what pulls the stain out of the stone and into the poultice material. After about 24 hours, remove the plastic and allow the poultice to dry.
- Remove the poultice from the stain, rinse with distilled water, and buff dry with a soft cloth. Use the wood or plastic scraper if necessary.
- Repeat the poultice application if the stain is not removed. It may take five or more applications for difficult stains.
- If the surface (calcareous stones) is etched by the chemical, apply polishing powder and buff with a polishing pad recommended by the polishing powder manufacturer.
It is possible that some stains may never be completely removed. Consult with a natural stone professional to determine additional steps that might be taken.
Care and Maintenance recommended by Natural Stone Institute.