Removing stains from marble, granite, and other natural stone surfaces can be difficult. So the best thing you can do is to take some precautionary measures.
What to Do with Spills and Stains
It’s crucial to clean any spill as soon as possible. You can do it by blotting spills with a paper towel or clean rag. At this stage, you should only blot a spill because if you try to wipe it, you may spread it over a larger area and make a larger mess. Use only cold water and stone soap or a neutral cleaner and rinse the area several times.
If a stain is still present, you will need to remove it. But you should avoid using any chemicals until you know which chemical cleaner to use for this type of stains and specific type of stone.
Types of Stains and First Step Cleaning Actions
In this section, you’ll find recommendations on removing different types of stains and what household chemicals to use.
Oil-based
These are stains from grease, cooking oil, milk, tar, or cosmetics. They will typically darken the stone, so you should remove them by chemically dissolving them. Then, you need to flush or rinse away the source of the stain. Oil-based stains can be cleaned with a soft liquid cleanser with bleach, ammonia, household detergent, mineral spirits, or acetone.
Metal
These are stains from iron, rust, bronze, or copper. Iron and rust stains follow the shape of a staining object (nails, cans, screws, bolts) and are brown. Copper and bronze stains are caused by the action of moisture on nearby or embedded copper, bronze, or brass items. They can be green or muddy-brown. Metal stains are not easy to remove, and you will need to use poultices.
Organic
These are stains from tea, coffee, tobacco, fruit, urine, food, bark, leaves, or bird droppings. These organic substances may cause pinkish-brown stains that may disappear after you remove the source of the stain. If a stain is outdoors, the sun and rain will typically bleach it out after you remove the source. If stains are indoors, you will need to clean them with 12% hydrogen peroxide mixed with a few drops of ammonia.
Biological
These stains are caused by algae, mildew, lichens, moss, or fungi. You can clean them with diluted ammonia (1/2 cup in a gallon of water), bleach, or hydrogen peroxide. Be cautious: Never mix bleach and ammonia because this combination creates toxic gas!
Paint
You can scrape off small amounts of paint with a razor blade or remove them with lacquer thinner. But you will need a commercial heavy liquid paint stripper that contains caustic soda or lye to remove heavy paint coverage. You should strictly follow the manufacturer’s instructions and protect yourself with eye protection and rubber gloves. Never try to use flame tools or acids to remove paint from stone.
Acrylic and latex paints won’t normally cause staining, but oil-based paints, linseed oil, putty, caulks, and sealants may cause oily stains. You will need to follow the instructions for oil-based stains to remove them.
Ink
These are stains from magic markers, pens, and ink. They can be cleaned with bleach or hydrogen peroxide if it’s a light-colored stone. If it’s dark stone, you should use lacquer thinner or acetone.
Water spots and rings
They are caused by the surface accumulation of hard water. You will need to buff them with dry 0000 steel wool.
Etch marks
These are a result of acids left on the surface of the stone. Some materials will etch the finish of the stone but won’t leave a stain, while others will both etch and stain. You will need to remove the stains, wet the stone surface with clear water, and sprinkle on marble polishing powder.
You should rub the powder onto the stone with a damp cloth. You can also do it using a buffing pad with a low-speed power drill. You should continue the buffing process until the etch mark disappears. If there are any problems, you should contact your stone dealer or call a professional stone restorer to refinish or re-polish etched areas that you can’t remove.
Fire and smoke damage
Smoke- and fire-stained fireplaces and older stones are not easy to clean, and it can be very time-consuming to restore their original appearance. So you should use commercially available smoke removal products that can save you a lot of time.
Efflorescence
It’s a white powder that may appear on the surface of the stone. Efflorescence occurs when the water rises from below the surface of the stone and evaporates, leaving behind salt deposits on the stone surface. If you see this powder on a new installation, you should dust mop or vacuum it. Most likely, you’ll have to do it several times as the stone dries out. If this problem persists, you should contact your installer, who can help you identify and remove the cause of the moisture.
Poultices
A poultice is the combination of an absorbent medium (it must be more absorbent than the stone) mixed with a chemical or a liquid cleaner, which is to be selected in accordance with the type of stain that you need to remove. You need to spread the poultice over the stained area with a wood or plastic spatula (to a thickness of about 1/4 to 1/2 inch). Then, you’ll have to cover it with plastic and leave it to work for 24 to 48 hours. The chemical or liquid cleaner will draw out the stain into the absorbent material.
Poultice materials include kaolin, powdered chalk, diatomaceous earth, whiting, fuller earth, talc, or white molding plaster. You can also use white cotton balls, whitepaper towels, or gauze pads.
Cleaning Agents or Chemicals
The choice of a cleaning agent or chemical will depend on the specific type of stain you need to remove.
- Organic stains – make a poultice with one of the powdered poultice materials and 12% hydrogen peroxide solution, or you may use acetone instead of the hydrogen peroxide.
- Oil-based stains – you should make a poultice with baking soda and water or one of the powdered poultice materials and mineral spirits.
- Biological stains – make a poultice with dilute ammonia or bleach, or hydrogen peroxide.
- Iron stains – make a poultice with diatomaceous earth and a commercially available rust remover.
- Copper stains – make a poultice with one of the powdered poultice materials and ammonia.
How to Apply the Poultice
Before you make an attempt to remove a stain, you should make sure you know what has caused it. Then, you need to prepare the poultice. If you use powder, mix the cleaning agent or chemical to a thick paste that has the consistency of peanut butter. If you use paper, soak it in the chemical and let it drain.
Follow these steps to apply the poultice.
- Pre-wet the stained area with distilled water.
- Apply the poultice to the stained area, overlapping the stain by at least ¼ inch. Don’t make the application too thick, or it will take a long time to dry.
- Cover the poultice with plastic and tape the edges to seal it using low-contact tape.
- Allow the poultice to dry for about 24 hours. Then, remove the plastic cover and allow the paste to dry thoroughly.
- Remove the poultice from the stain by scraping. Rinse the area with distilled water and buff it dry with a soft cloth.
- If the stain is not removed, you may need to repeat the process. For difficult stains, you may need to repeat the process up to 5 times.
Unfortunately, some stains may never be completely removed if you try to do it yourself, so you will need to consult with a stone professional to find out what additional steps might be taken.
