Jan 31, 2015 5 min read

Wow, did we get a lot of responses from you guys on granite countertop issues. Seems like our sealing tip was both timely and needed. We do not have the space to print every question, but I hope to address all of your concerns here:

Q. Loved your video on sealing granite. I would like to seal our marble bathroom floor, but I am unable to clean the grout. We installed marble (10-by-10) tiles in our bathroom. The installer used white grout (we mistakenly chose the light color). Now the grout is very dirty and hard to clean. I’m always concerned that I will ruin the marble when trying to clean the floor. Any ideas?

A. I used to have a 4-by-4-tile countertop. What a mistake that was; it took no time for the grout to look nasty! The method I used back then to clean my tile grout would work for you. It involves baking soda and a toothbrush. Baking soda is amphoteric, which means that it can react as an acid as well as a base, allowing it to dissolve as well as neutralize compounds, making it a formidable, yet gentle cleaner.

Make a blend of warm water and baking soda and mix until you get the consistency of hand cream. Use a toothbrush to apply it, cleaning only the grout. Rinse with warm water, dry it immediately, then rinse and repeat until clean.

Alternatively, since you said “very dirty,” you may want to try a chemical cleaner designed for marble and grout. These cleaners contain phosphoric acid in their formulation, which will not etch marble or limestone.

These chemical cleaners are easy to use as long as you protect adjacent areas like wood floors, trim, and carpets. Once you are finished, seal your floor!

Q. When my granite counters were put in a few years back, the worker talked me into buying a marble- and stone-care kit. I have never used it. It has a cleaner, stain repellant, and stone polish. I do not know where to start, even though I have read the instructions several times. I thought I had my counters sealed, but the guy that came just did the edges. Can you recommend anyone who does this sealing? I don’t know if I can handle it. I watched your video and it sounds easy. Thank you.

A. Any handyman will do this for you, or call a local granite or tile store and ask them to do it.

Q. I have an oil stain that is a bit larger then a quarter on my new bathroom vanity granite top. How can I get this out so that I can properly seal the granite? If I seal the countertop before I remove the oil, the stain will then be trapped under the seal. Also does the sealer change the color of lighter granite? Is there a brand of sealer that lasts a long time before it needs to be redone? Thanks.

A. A tough call and a lot of questions! If you seal the granite without removing the stain, the stain will still be there, yes. Sealers can darken granite, so I would test it in an inconspicuous spot prior to applying it. As far as lasting a long time, I do not have that answer. Applying a sealant to a bath vanity takes a matter of minutes, so, for me, this is not really an issue. I would call and ask professional granite installers for a product referral.

I am torn about whether I would remove the stain myself or call my local granite and tile store for advice or a referral. If I had the intestinal fortitude, I would first try a paste of baking soda and cover it with plastic wrap, taping down the edges. I’d let it sit overnight and clean it off in the morning with dish soap and water. If that did not work, I would probably call for professional help.

However, If you are feeling gutsy, you can use pure acetone (not nail polish remover), a common and popular cleaner. I use it a lot in my trade, and it is a recommended cleaner for oil stains on granite. Acetone is low in toxicity but highly flammable, so it is essential to have good ventilation and keep it away from ignition sources.

To apply the acetone, you will need a delivery system. A granite installer I know recommends using an absorbent material, such as thick, high-quality paper towels, talcum powder, or diatomaceous earth to soak up the acetone and apply it directly to the stain.

If using talcum powder or diatomaceous earth, the mixture should be thick and pasty. Apply it to the stain only, cover it with plastic wrap, and tape the edges for 24 hours. Remove the tape and allow your mixture to dry completely before wiping with a clean rag. Wash normally with soap and water and evaluate the stain. Unfortunately, it might take you a few attempts to get the stain 100 percent out.

Again, I would probably hire someone to do this for me.