Stone is a natural product and simple care and maintenance will keep it looking beautiful.
Care and Precautions:
Use coasters under all glasses, particularly those containing alcohol or citrus juices. Many common foods and drinks contain acids that will etch or dull the surface of many stones.
Do not place hot items directly on the stone surface. Use trivets or mats under hot dishes and placemats under china, ceramics, silver or other objects that can scratch the surface.
Cleaning Procedures & Recommendations:
- Clean stone surfaces with a few drops of neutral cleaner, stone soap (available from hardware stores or from your stone dealer) or a mild liquid dishwashing detergent and warm water.
- Use a clean rag mop on floors or a soft cloth for other surfaces for best results.
- Too much cleaner or soap may leave a film or cause streaks.
- Never use products that contain lemon, vinegar or other acids on marble or other calcareous stones.
- Rinse the surface thoroughly after washing with the soap solution and dry with a soft cloth
- Change the rinse water frequently.
- Do not use scouring powders or creams; these products contain abrasives that may scratch the stone.
In food preparation areas, the stone may need to have a penetrating sealer applied. Check with your installer for recommendations. If a sealer is applied, be sure that it is non-toxic and safe for use on food preparation surfaces. If there is a question, check with the sealer manufacturer.
Vanity tops may need to have a penetrating sealer applied. Check with your installer for recommendations. A good quality marble wax or non-yellowing automobile paste wax can be applied to minimize water spotting.
In the bath or 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 stone.
Know Your Stone:
Natural stone can be classified into two general categories according to the 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 for calcareous surfaces.
How to Tell the Difference Between Calcareous and Siliceous Stone:
A simple acid sensitivity test can be performed to determine whether a stone is calcareous or siliceous. You will need a few drops of vinegar and an eyedropper. Because this test may permanently etch the stone, select an out of the way area (a corner or closet) and several inches from the mortar joint. Apply a few drops of the vinegar to the stone surface on an area about the size of a quarter. If the stone is calcareous, the vinegar will etch the stone. If little or no reaction occurs, the stone can be considered siliceous. Rinse the area thoroughly with clean water and wipe dry.
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 stone away and apply the vinegar to the fractured surface.
If in doubt, contact your stone installer for information on the type of stone installed.
Stone Finishes:
A polished finish on the stone has a glossy surface that reflects light and emphasizes the color and markings of the material. This type of finish is used on walls, furniture tops, countertops and other items, as well as floor tiles.
A honed finish is a satin smooth surface with relatively little light reflection. Generally, a honed finish is preferred for floors, stair treads, thresholds and other locations where heavy traffic will wear off the polished finish. A honed finish may also be used on countertops, furniture tops and other surfaces.
A flamed finish is a rough textured surface used frequently on granite floor tiles.
Stone Colors and Appearance:
Granites and marbles are quarried throughout the world in a variety of colors with varying mineral compositions. In most cases, marbles and granites can be identified by visible particles at the surface of the stone. Marble will normally show “veins” or high concentrations of minerals. The minerals in granite will typically appear as small flecks distributed uniformly in the stone. Each type of stone is unique and will vary in color, texture and marking.
Sandstones vary widely in color due to different minerals and clays found in the stone. Sandstone is light gray to yellow or red. A dark reddish-brown sandstone, also called brownstone, has commonly been used in the northeastern United States and eastern Canada. Bluestone is a dense, hard, fine-grained sandstone of greenish-gray or bluish-gray color and is quarried in the eastern United States.
Limestone is a widely used building stone with colors typically light gray, tan or buff. A distinguishing characteristic of many limestones is the presence of fossils that are frequently visible in the stone surface.
Slate is dark green, black, gray, dark red or multi-colored. It is most commonly used as a flooring material and for roof tiles and is often distinguished by its distinct cleft texture.
Spills and Stains:
Blot the spill with a paper towel immediately. Don’t wipe the area, it 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 below on stain removal.
Stain Removal:
Identifying the type of stain on the stone surface is the key to removing it. If you don’t know what caused the stain, play detective. Where is the stain located? Is it near a plant, a food service area, an area where cosmetics are used? What color is it? What is the shape or pattern? What goes on in the area where the stain occurred?
Surface stains can often be removed by cleaning with an appropriate cleaning product or household chemical. Deep-seated or stubborn stains may require using a poultice or calling in a professional. The following sections describe the types of stains that you may have to deal with and appropriate household chemicals to use and how to prepare and apply a poultice to remove the stain.
Types of Stains & First Step Cleaning Actions:
Oil-based (Grease, tar, cooking oil, dairy, cosmetics): An oil-based stain will darken the stone and normally must be chemically dissolved so the source of the stain can be flushed or rinsed away. Clean gently with a soft, liquid cleanser with bleach OR household detergent OR ammonia OR mineral spirits OR acetone. DO NOT 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.
Organic (Coffee, tea, fruit, tobacco, paper, food, urine, leaves, bark, bird droppings): May cause a pinkish-brown stain and may disappear after the source of the stain has been removed. Outdoors, with the sources removed, normal sun and rain action will generally bleach out the stains. Indoors, clean with 12% hydrogen peroxide (hair bleaching strength) and a few drops of ammonia.
Metal (iron, rust, copper, bronze, brass): Iron or rust stains are orange to brown in color and follow the shape of the staining object such as nails, bolts, screws, cans, flower pots, metal furniture. Copper and bronze stains appear as green or muddy-brown and result from the action of moisture on nearby embedded bronze, copper or brass items. Metal stains must be removed with a poultice (see section below on Making & Using a Poultice). Deep-seated, rusty stains are extremely difficult to remove and the stone may be permanently stained.
Biological (algae, mildew, lichens, moss, fungi): Clean with dilute (1/2 cup in a gallon of water) ammonia OR bleach OR hydrogen peroxide. DO NOT MIX BLEACH AND AMMONIA! THIS COMBINATION CREATES A TOXIC AND LETHAL GAS!
Ink (magic marker, pen, ink): Clean with bleach OR hydrogen peroxide (light colored stone only!) OR lacquer thinner OR acetone (dark stones only!).
Paint: 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 “heavy liquid” stripper available from hardware stores or paint centers. Do not use acids or flame tools to strip paint from stone. Paint strippers can etch the surface of the stone; re-polishing may be necessary. Follow the manufacturer’s directions for use of these products, taking care to flush the area thoroughly with clean water. Protect yourself with rubber gloves and eye protection, and work in a well-ventilated area. Use only wood or plastic scrapers for removing the sludge and curdled paint. Normally, latex and acrylic paints will not cause staining. Oil-based paints, linseed oil, putty, caulks and sealants may cause oily stains. Refer to the section on oil-based stains.
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 fireplaces may require a thorough cleaning to restore their original appearance. Commercially available “smoke removers” may save time and effort.
Etch Marks are caused by acids left on the surface of the stone. Some materials will etch the surface but will not leave a stain. Others will both etch and stain. Once a stain is removed, wet the surface with clear water and sprinkle on marble polishing powder, available from a hardware or lapidary store, or your local stone dealer. Rub the powder onto the stone with a damp cloth or by using a buffing pad with a low-speed power drill. Continue buffing until the etch mark disappears and the marble surface shines.
Contact your stone dealer or call a professional stone restorer for refinishing or re-polishing etched areas you cannot remove.
Efflorescence is a white powder that may appear on the surface of the stone. It is caused by water carrying mineral salts to the surface of the stone and evaporating. When the water evaporates, it leaves the powdery substance. If the installation is new, dust or vacuum the powder. You may have to do this several times as the stone dries out. Do not use water to remove the powder as it will only temporarily disappear. If the problem persists, contact your installer to help identify and remove the cause of the moisture.
Scratches and Nicks Slight surface scratches may be buffed with dry 0000 steel wool. Or, refer to the section on Etch Marks and follow the polishing procedure. Deeper scratches and nicks in the surface of the stone should be repaired and repolished by a professional.
Making & Using a Poultice:
A poultice is a liquid cleaner or chemical mixed with a white absorbant material to form a paste about the consistency of peanut butter. The poultice is spread over the stained area to a thickness of about ¼ to ½ inch with a wood or plastic spatula, covered with plastic and left to work for 24 to 48 hours. The liquid cleaner or chemical will draw out the stain into the absorbant material. Poultice procedures may have to be repeated to thoroughly remove the stain, but some stains may never be completely removed.
Poultice Materials:
Poultice materials include kaolin, fuller’s earth, whiting, diatomaceous earth, powdered chalk, white molding plaster or talc. Approximately one pound of 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.
Cleaning Agents or Chemicals:
Oil-based stains: Poultice with baking soda and water OR one of the powdered poultice materials and mineral spirits.
Organic Stains: Poultice with one of the powdered poultice materials and 12% hydrogen peroxide solution (hair bleaching strength) OR use acetone instead of hydrogen peroxide.
Iron Stains: Poultice with diatomaceous earth and a commercially available rust remover. Rust stains are particularly difficult to remove. You may need to call a professional.
Copper Stains: Poultice with one of the powdered poultice materials and ammonia. These stains are difficult to remove. You may need to call a professional.
Biological Stains: Poultice with one of the poultice materials and dilute ammonia OR bleach OR hydrogen peroxide. DO NOT MIX BLEACH AND AMMONIA! THIS COMBINATION CREATES A TOXIC AND LETHAL GAS!
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 in the chemical and let drain. Don’t let the liquid drip.
- Wet the stained area with distilled water.
- Apply the poultice to the stained area about ¼ to 1/2 inch thick and extend the poultice beyond the stained area by about one inch. Use a wood or plastic 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 up to five applications for difficult stains.
- If the surface is etched by the chemical, apply polishing powder and buff with burlap or felt buffing pad to restore the surface.
Do’s and Don’ts:
- DO Dust mop floors frequently.
- DO Clean surfaces with mild detergent or stone soap.
- DO Thoroughly rinse and dry the surface 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 scrub 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.
Call your professional stone supplier, installer or a restoration specialist for problems that appear too difficult to treat.
This information is provided to you by the Members of the Marble Institute of America. Look for the MIA logo for quality services in natural stone products and installations.