Identifying the type of stain on the stone surface is 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, bar, 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 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. 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)
Clean with bleach or hydrogen peroxide (light colored stone only!) or laquer thinner or acetone (dark stones only!)
Small amounts can be removed with a lacquer thinner or scraped off carefully with a razor blade. Heacy 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 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 pain. 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 accumulations of hard water)
Buff with dry 0000 steel wool.
Fire and Smoke Damage
Older stones and smoke or firestained 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 clean 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.
Poultice materials include kaolin, fuller’s earth, whiting, diatomaceous earth, powdered calk, white molding plaster or talk. 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
Poultice with baking soda and water OR one of the powdered poultice materials and mineral spirits.
Poultice with one of the powdered poultice materials and 12% hydrogen peroxide solutions (hair bleaching strength) OR use acetone instead of the hydrogen peroxide.
Poultice with diatomaceous earth and a commercially available rust remover. Rust stains are particularly difficult to remove. You may need to call a professional.
Poultice with one of the powdered poultice materials and ammonia. These stains are difficult to remove. You may need to call a professional.
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 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 1/4 to 1/2 inch think 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 buss with burlap or felt buffing pad to restore the surface.
A Few Things to Remember:
If a spill should occur, clean up before the stain has a chance to penetrate the surface. Granite is somewhat absorbent, and can absorb stains if spills are left any length of time.
- Granite is most prone to staining by oil and acid.
- Removing diamond rings before cooking is recommended.
- Generally, you can clean your granite countertop with a neutral cleaner and a soft clean cloth. Consider using a disinfectant cleaner made specifically for granite. With the growing popularity of granite countertops, these are easy to find.
- Using regular cleaning chemicals on your countertop will strip the seal and leave the porous surface of the granite exposed.
- Don’t be afraid to call us for suggestions on maintenance, care, and cleaning.
If stains and scratches do occur, there are many things you can do on your own to remove them. Here are a couple of examples:
Oil-based Stains (e.g. grease, oil, milk)
Mix a cup of flour, 1-2 tablespoons of hydrogen peroxide with water to make a thick paste. Smear the paste on the stain, cover it with plastic wrap and leave it over night. Scrape away the mixture with a wooden utensil and rinse. You can also remove oil-based stains with acetone, mineral spirits, or bleach or ammonia diluted in water. (NEVER mix ammonia and bleach together!).