Q. I know that you have a lot of replies but I'm really hoping you can help me with this. My father decided to try to clean our floors (marble) with Clorox and water, but I think the mixture might have been slightly too strong. Since the marble floors were not completely without cracks to begin with, the Clorox seemed to have dried and hardened into white clumps in certain areas? I don't know how to clean it, and if I have to live with it, would using other cleaning products on it still be dangerous? I have tried to scrub at it with water, but it just comes back.

A. I am so sorry about your floor, and wish I had better news for you. We recommend against using Clorox® Regular-Bleach to clean marble and other porous stone surfaces. From your description, it sounds like the problem is mainly in the cracked areas. This makes a lot of sense in that the main surface was probably sealed to protect it, but the cracks wouldn’t have that same protection. Therefore, a negative reaction with the bleach will be much more pronounced in the cracks. The white clumps you have are probably water insoluble deposits resulting from the calcium carbonate in the marble chemically reacting with the bleach. You can try to remove them with vinegar (acetic acid) because it will dissolve calcium carbonate—the trick is to remove the deposits without damaging the surrounding marble (vinegar is also not recommended for marble), which might be possible depending on how much sealant remains on the marble and how quickly you work. However, your floor probably won’t be completely restored in that the cracked areas will still be etched whiter than the surrounding area. The biggest problem with marble is that it should only be cleaned with pH neutral solutions like water, which protect the marble at the expense of powerful cleaning.