Preserving the
Beauty of Your NATURAL STONE
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
under hot dishes and placemats under china, ceramics,
silver or other objects that can scratch the surface.
Cleaning Procedures and
Recommendations
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.
Do not use vacuum cleaners that are worn. The metal or
plastic attachments or the wheels may scratch the
surface.
Clean stone surfaces with a few drops of neutral
cleaner, stone soap or a mild liquid dishwashing
detergent and warm water. Use a clean rag mop on floors
and a soft cloth for other surfaces 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 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 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.
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 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.
In outdoor pool, patio or hot tub areas, flush with
clear water and use mild bleach solution to remove algae
or moss.
Know Your 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.
How to tell the difference
A simple acid sensitivity test can be performed to
determine whether a stone is calcareous or siliceous.
You will need about 4 oz. Of a 10% solution of muriatic
acid and an eyedropper. Or you can use household 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 away from the mortar
joint. Apply a few drops of the acid solution to the
stone surface on an area about the size of a quarter. If
the stone is calcareous, the acid drops will begin to
bubble or fizz vigorously. 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 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.
Stone Finishes
A polished finish on the stone has a glossy surface that
reflects light and emphasizes the color and marking of
the material. This type of finish is used on walls,
furniture tops 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 threads, thresholds and
other locations where heavy traffic will wear off the
polished finish. A honed finish may also be used on
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. 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 or 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 in
this brochure 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 around the stain?
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 and First Step Cleaning Actions
Oil-based (grease, tar, cooking oil, milk, 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.
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) 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 or embedded bronze, copper
or brass items. Metal stains must be removed with a
poultice. (See section 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 diluted (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 only with a commercial “heavy
liquid” paint stripper available from hardware stores
and paint centers. These strippers normally contain
caustic soda or lye. Do not use acids or flame tools to
strip paint from stone. Paint strippers can etch the
surface of the stone; repolishing 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 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 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 repolishing etched areas
that 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 from below the surface of the stone rising
through the stone and evaporating. When the water
evaporates, it leaves the powdery substance.
If the installation is new, dust mop 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;
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. Deeper scratches and
nicks in the surface of the stone should be repaired and
repolished by a professional.
Making and Using a Poultice
A poultice is a liquid cleaner or chemical mixed with a
white absorbent 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
absorbent material. Poultice procedures may have to be
repeated to thoroughly remove a 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
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.
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 the
hydrogen peroxide.
Iron Stains: Poultice with diatomaceous earth and
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 dilute ammonia OR
bleach OR hydrogen peroxide. DO NOT MIX AMMONIA AND
BLEACH! THIS COMBINATION CREATES A TOXIC AND LETHAL GAS!
Applying the Poultice
Prepare the poultice. If using a 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 ½ 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 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.The natural
stone you have purchased for your home or office is an
investment that will give you many years of beautiful
service. Simple care and maintenance will help preserve
your stone's beauty for generations to come. The
information to the left is developed for you by the
Marble Institute of America to offer routine cleaning
guidelines as well as procedures for stain removal,
should such become necessary. This information is
provided for reference only and is not to be construed
as contractual.
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