Most stone will stain because it is porous. This allows fluids to enter and become embedded below the surface. The longer a stain remains, the deeper it penetrates and becomes more permanent; therefore, it is important to remove a stain as soon as it occurs. This applies to any stone used in the construction of your sink.
Granite is a very durable, resilient stone. For regular cleaning, use a soapy nylon brush in a circular motion and rinse thoroughly. Cleaning on a regular basis will help prevent the development of hard water deposits. If you develop persistent stains, try a non-abrasive cleaner such as dishwasher soap, a bleach solution, or Soft Scrub. Be sure to avoid strong alkalis such as ammonia and drain unblocking chemicals that involve filling the sink with water. If you encounter a rust stain, usually caused by iron particles from water, cookware, etc., use a cleaner containing oxalic acid. Do not use bleach directly on granite!
Marble has a shiny, elegant finish. Maintaining this look can be difficult due to the porosity of the stone. Sealing helps keep the stone from absorbing fluids, but acidic liquids, such as orange juice, lemons, soft drinks, various foods, and common household cleaners, will cause a dull etched spot. For this reason, do not use acidic cleaners on your marble. Wet glasses containing slightly acidic liquids can cause hard water spots. To avoid water spots, rinse and dry your sink after each use. The only way to remove etching and water spots is by refinishing and re-polishing by a professional. For regular care, use a soft, liquid cleanser with bleach or a common household detergent.
Limestone is known for the seashells and fossils embedded into it. Some Limestone is “soft”, so you should be careful about scratching or nicking the surface when using sharp objects. Limestone should be periodically treated with a penetrating sealant to protect against staining, especially when working with acidic materials.
For removing difficult stains on all stone types try the following steps before consulting an expert.
1) Clean the area using a stone cleaner with a neutral pH. If this does not help, try a more aggressive cleaner. Keep in mind what types of stones are sensitive to certain chemicals, as stated above.
2) Wet your surface with distilled water. This will keep the chemical from drying too fast, allowing it to stay in contact with the stain longer.
3) Prepare a poultice. This will be used to absorb the stain out of the stone. An easy poultice to create at home requires mixing one cup of flour and a few tablespoons of liquid dish detergent. Mix the two together until you have the consistency of peanut butter. You can purchase chemical poultices if you prefer. *For stains with red wine, replace the detergent with hydrogen peroxide.
4) Thickly cover the stain in the poultice you have created and cover with saran wrap and tape the edges down with masking tape (won’t create a permanent residue), then let sit overnight.
5) After 24 hours, remove the plastic. Let sit uncovered until poultice is dry. This step is important because the drying is what pulls the stain out of the stone. You can then remove the poultice by scraping it off with a razor blade or putty knife. Clean off the residue with water and a neutral cleaner. *Granite is more porous than other stones so it will retain moisture longer. If the stain appears to be gone, but the stone is a slightly darker color, give it a week or more to dry before reattempting the poultice method.