to Know Your Stone
first step in proper stone care and maintenance is to understand your
stone’s geological classification and composition. this information will
help you to identify what cleaning products to use and how best to care
for your natural stone.
stone is categorized into three basic geological classifications by their
respective formation processes: Sedimentary, Metamorphic and igneous.
Additionally, stones in each category can be either Calcareous or
stone is composed mainly of calcium carbonate, a chemical compound
commonly found in natural stone, shells and pearls. Calcium Carbonate is
sensitive to acidic solutions so mild, non-acidic cleaners are
stone, as the term implies, is one composed primarily of silicates, such
as quartz, feldspar, mica, etc. as such, a siliceous stone is generally
resistant to most acids found in kitchen settings, although acidic
cleaners are still not recommended, as these stones may contain trace
levels of minerals that are acid sensitive.
following chart will be a helpful guide:
get the longest life and preserve the beauty of your natural stone, follow
these simple tips:
Use coasters under all glasses, particularly those containing alcohol or
While many stones can withstand heat, the use of trivets or mats is
Mopping: Dust mop interior floors frequently using a clean
non-treated dry dust mop. Sand, dirt and grit are abrasive and can damage
Mats or area rugs inside and outside an entrance will help to minimize the
sand, dirt and grit that may scratch the stone floor. Be sure that the
underside of the mat or rug is a slip resistant surface.
cleaners: If used, be sure the metal or plastic attachments or
the wheels are not worn as they can scratch the surface of some stones.
Blot the spill with a paper towel immediately. Do not wipe the area, it
will spread the spill. Flush the area with water and mild soap and rinse
several times. Dry the area thoroughly with a soft cloth. Repeat as
stone surfaces with a neutral cleaner, stone soap, or a mild liquid
dishwashing detergent and warm water.
to any item cleaned in your home, an excessive concentration of cleaner
or soap may leave a film and cause streaks. Follow manufacturer
a clean rag mop on floors and a soft cloth for other surfaces for best
the surface thoroughly after washing with the soap solution and dry with
a soft cloth.
the rinse water frequently.
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 1/2 cup ammonia to a
gallon of water). Frequent or over-use of an ammonia solution may
eventually dull the surface of some stone types.
outdoor pool, patio or hot tub areas, flush with clear water and use
mild bleach solution to remove algae or moss.
suppliers offer products used for stone cleaning.
containing lemon, vinegar or other acids may dull or etch calcareous
powders or creams often contain abrasives that may scratch certain
commercially available rust removers (laundry rust stain removers,
toilet bowl cleaners) contain trace levels of hydrofluoric acid (HF).
This acid attacks silicates in addition to other minerals. All stones,
including granite and quartzite, will be attacked if exposed to HF.
not mix ammonia and bleach. This combination creates a toxic and lethal
is a common step taken on some stones as an extra precaution against
staining. In fact, the sealing products used in the stone industry are
‘impregnators’ which do not actually seal the stone, but more correctly
act as a repellent rather than a sealer. Sealing does not make the stone
stain proof, rather it makes the stone more stain resistant. When
consulting with your stone supplier, you may find that many stones do not
require sealing. However, applying an impregnating sealer is a common
considering sealing, remember that sealing the stone does not make the
stone stain proof, it makes it more resistant to staining.
a sealer is applied in a food preparation area, be sure that it is
non-toxic and safe for use.
with your supplier or sealing manufacturer specific to the type of sealer
and frequency of use recommended.
the type of stain on the stone surface is the key to removing it. Stains
can be oil based, organic, metallic, biological, ink based, paint based,
acid based. If you don’t know what caused the stain, consider likely
staining agents that may have been present. Here are some questions you
is the Stain Located?
it near a plant, a food service area, an area where cosmetics are used?
color is it?
is the shape or pattern?
occurs in the area around the stain?
stains can often be removed by cleaning with an appropriate cleaning
product or household chemical.
Type of Stain is It?
following sections describe the types of stains you may have to deal with
and the appropriate household chemicals to use and how to prepare and
apply a poultice to remove the stain.
(grease, plumbers’ putty, 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 one of the following: household
detergent, mineral spirits, or acetone.
(coffee, tea, wine, fruit, tobacco, paper, food, urine, leaves, bark, bird
May cause a pinkish-brown stain and may disappear after the source of the
stain has been removed. Outdoors, with the sources removed, 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.
(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 website on
Using a Poultice –
Deep-seated, rustystains are extremely difficult to remove and the stone
may be permanently stained.
(algae, mildew, lichens, moss, fungi)
Clean with diluted cleaning solution. Use a 1/2 cup of any of the
following: ammonia, bleach, or hydrogen peroxide and a gallon of water.
Reminder: do not mix bleach and ammonia.
(magic marker, pen, ink)
On light colored stones, clean with bleach or hydrogen peroxide. On dark
colored stones, clean with lacquer thinner or acetone.
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, and 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.
Spots and Rings
(surface accumulation of hard water)
Buff with dry 0000 steel wool.
and Smoke Damage
Older stones and smoke or firestained fireplaces may require a thorough
cleaning. When the smoke is removed, there may also be some etching (due
to carbonic & other acids in smoke). Commercially available “smoke
removers” may save time and effort.
(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. Contact your stone dealer or call a professional
stone restorer for refinishing or repolishing etched areas.
(a white powder that may appear on the surface of the stone)
It is caused by the deposition of mineral salts carried by water from
below the surface of the stone. 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.
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.
Go to www.marble-institute.com/consumers/poultices.cfm for more information, or call
a stone professional (recommended).