How To Clean General Grime from Natural Stone
Grime can be challenging because it is generally a greasy, combination stain, which requires a multi-prong approach. Additionally, natural stone varies in their reaction to stains and to the methods used to clean them. Generally speaking, non-abrasive, pH neutral or mildly alkali remedies are best. Natural stone surfaces, particularly marble, are sensitive to acids, so acidic remedies like citrus-based cleansers and vinegar should be avoided. Although many natural stone surfaces, whether sealed or simply polished, are attractive and durable additions to the home, they can be reactive to improper stain removal. The goal is to remove the stain while preserving the beauty, color and polish of the surface.
Because different surfaces can meet together, care must be exercised to prevent an inappropriate cleaner from getting onto adjoining surfaces. Keep clean dry paper towels or soft rags at hand to promptly wipe up stray cleaner that has landed on an incompatible material. Natural stone countertops are best cared for with mild pH neutral products, and should periodically be re-sealed so that they can continue to resist stains. If you don't know the nature of then stain you are working with or encounter a stain that resists removal, it may require the assistance of a professional. Taking the wrong steps can make the stain worse or damage the surface, so when in doubt, bring in a pro.
In the case of grime, it takes time to build up. That can mean set-in stains, but that also means that you can take your time removing it (whereas some fresh spills require quick action). Approaching a section at a time, working slowly and carefully will yield the best results. You will need a clean soft sponge, cotton swabs, clean rags or paper towels, a basin of water and a pH neutral detergent or soap like Dove. If you are concerned about hard water marks on marble, you can use distilled water rather than tap. Mix a lightly sudsy solution of cleaner and water. Apply to the caked on grime with the sponge, rubbing gently to help dislodge the stain. Avoid excess water build up, and periodically wipe away dislodged grime and sudsy solution. Use the cotton swabs for hard to reach areas like between tiles, in corners, and near appliance fittings. Although this technique should be sufficient to gradually dissolve the grime from the top layer down, it's possible that more creative techniques may be called for.
Corn starch is an item that's commonly available and is possibly already in your kitchen. For stubborn areas of caked on grime, put 1/4 cup of cornstarch in a shallow dish. Dip a cotton swab in the sudsy solution and then dip it in the corn starch. Apply directly to the problem areas with a gently rubbing motion. The corn starch will help to absorb the greasy portion of the grime, and break up the stain. If you don't have corn starch on hand, you may substitute baking soda. Keep in mind that baking soda is mildly alkali and abrasive. Test in an inconspicuous area and, if you decide to make this substitution, confine application to the grime itself rather than uncovered natural stone surface. Do not substitute cream of tartar or baking powder as they contain acid salts.
After the grime is removed, you may wish to follow with a light overall cleaning using fresh sudsy solution. Rinse well with water, particularly distilled, and use a squeegee to wick away extra moisture and help avoid pooling that may damage your natural stone surface.
If you notice an oily blot remaining, refer to our article on oil and grease removal from natural stone for precise directions on how to make a poultice to draw out the stain. If this is a flea market find or other type of restoration project, you may find commercially available natural stone color enhancers useful for returning color consistency to the surface.
Caution: Never mix cleaning agents or chemicals, the result can be dangerous or deadly. Before cleaning, always test the agent on an inconspicuous location to determine its suitability and to make certain it does not damage the material. Wear appropriate clothing such as gloves and protective eyewear, and work in a well-ventilated area.