Most stones will stain because they are porous. This allows fluids to enter and embed themselves 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 strong and very durable stone. For regular cleaning, use a soapy nylon brush in circular motions and rinse well. Regular cleaning will help prevent the development of hard water deposits. If you develop stubborn stains, try a non-abrasive cleaner such as dish soap, bleach solution, or Soft Scrub®. Be sure to avoid strong alkalis like ammonia and drain-unblocking chemicals that involve filling the sink with water. If you find a rust stain, usually caused by iron particles from water, kitchen utensils, etc., use a cleaner that contains oxalic acid. Do not bleach directly on granite!
Marble has a sleek, shiny finish. Maintaining this appearance can be difficult due to the porosity of the stone. The seal helps prevent the stone from absorbing liquids, but acidic liquids such as orange juice, lemons, soda, various foods, and common household cleaners will cause a dull stain. . For this reason, don’t use acidic cleaners on your marble. Wet glasses containing slightly acidic liquids can cause hard water stains. To avoid water stains, rinse and dry your sink after each use. The only way to remove etching and water stains is by professional repainting and polishing. For regular care, use a mild liquid cleaner with bleach or a common household detergent.
Limestone is known for the seashells and the fossils embedded in it. Some limestone is “soft”, so be careful not to scratch or nick the surface when using sharp objects. Limestone should be periodically treated with a penetrating sealer to protect it from staining, especially when working with acidic materials. Possible sealants include Safecoat MexeSeal®, Seal & Go “S” ®, and Seal & Go “Enhancer” ®.
Soapstone has a silky smooth finish. It is extremely dense so it repels stains well. This stone is the least porous of the stones that are used in kitchen or bathroom sinks and vessels. To clean, use a damp cloth or sponge with a mild cleaner. Your soapstone sink should be treated monthly with mineral oil.
To remove tough stains on all types of stone, try the following steps before consulting an expert.
1) Clean the area with a neutral pH stone cleaner. If this doesn’t help, try a more aggressive cleaner. Consider what types of stones are sensitive to certain chemicals, as stated above.
2) Moisten its surface with distilled water. This will prevent the chemical from drying too quickly, allowing it to stay in contact with the stain longer.
3) Prepared for poultice. This will be used to absorb the stain from the stone. An easy poultice to create at home requires mixing a cup of flour and a few tablespoons of liquid dish soap. Mix the two until it is the consistency of peanut butter. You can buy chemical poultices if you prefer.
* For red wine stains, replace detergent with hydrogen peroxide.
4) Cover the stain in the poultice you have created and cover with saran wrap and tape the edges (will not create a permanent residue), then let it sit overnight.
5) After 24 hours, remove the plastic. Let stand uncovered until poultice is dry. This step is important because drying is what removes the stain from the stone. You can then remove the poultice by scraping it off with a razor blade or spatula. Clean the residues with water and a neutral cleaner.
* Granite is more porous than other stones, so it will retain moisture for longer. If the stain appears to be gone, but the stone is a slightly darker color, allow it to dry for a week or more before trying the poultice method again.
For more information on stone sinks, whether for the kitchen, bathroom or bar, visit the Sink Gallery where you will find the largest variety of artisan and handmade sinks available anywhere. There are several more articles online in the “tips” section.