Cleaning your Stone

The beauty of natural stone is enhance by its ease of maintaining the surface.  To clean, maintain and preserve the natural elegance of stone just use warm water and a mild dishwashing liquid with a soft cloth. Rinse with clean water and buff dry and that will keep your countertops looking great for years to come.  However, should a stain occur, it can usually be removed with a poultice and by following the procedure below.

Know your Stone
One of the most common educational seminars I presented over the years has been defining the various types of natural stones that are being used in the industry today.  Knowing whether a stone is granite, marble, limestone or one of the many others that are marketed today is crucial to knowing what and how to effective clean natural stone.

There are two very general classifications that are based on the mineral composition of the stone: siliceous stone or calcareous stone.  What cleaners are effective on siliceous type stones can very well be harmful to calcareous type stones.

Siliceous stone is mainly made up of particles that are silica or quartz in nature. These types of particles tend to be very hard and durable, thus relatively easy to clean with mild acidic cleaning solutions. Types of siliceous stone include granite, quartzite, slate, sandstone, brownstone and bluestone.

Calcareous stone is composed mainly of calcium carbonate. Calcareous stones are sensitive to acidic cleaning products and frequently require different cleaning procedures than siliceous stone. Types of calcareous stone include marble, travertine, limestone and onyx.

How can you identify the difference?  A simple acid test can be done on the surface of the stone to determine which classification of stone you have.  Words of CAUTION! First pick an indiscriminate location to try an acid test because it can damage the surface of the stone if calcareous in nature. A sample of the stone would be great to experiment because some surface sealers may impact the effectiveness of the test. Second, always use proper head and body protection when using acids. An eyedropper with diluted phosphoric or muriatic acid will work as does household vinegar.  It the drop of acid bubbles or fizz, then you are looking at a calcareous type stone.  If nothing happens, then the stone can be considered siliceous.

Know your stain

Knowing what is the cause of a stain is paramount to correcting the problem.  As you can imagine, there are many different types of possible stains and below are some typical classifications.

Oil-Based Stains: Grease, tar, cooking oil and food stains.  Poultice with baking soda and water OR one of the powdered poultice materials and mineral spirits.

Organic Stains: Coffee, tea, fruit, tobacco, cosmetics, etc. Poultice with one of the powdered poultice materials and 12% hydrogen peroxide solution (hair bleaching strength) OR use acetone instead of the hydrogen peroxide.

Metal Stains: Iron (rust), copper, bronze, etc. Poultice with diatomaceous earth and a commercially available rust remover. Rust stains are particularly difficult to remove. You may need to call a professional.

Biological Stains: Algae, mildew, lichens, etc. Poultice with dilute ammonia OR bleach OR hydrogen peroxide. DO NOT MIX AMMO-NIA AND BLEACH! THIS COMBINATIONCREATES A TOXIC AND LETHAL GAS!

Ink Stains: Magic marker, pen, ink, etc. Poultice with Mineral Spirits or Methylene Chloride and powder.

DIRECTIONS:  Prepare the poultice.  What is a poultice? Clays (not iron type clays) and diatomaceous earth are usually the best. 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 about1/4 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.