Hello Tom: Just discovered your web site. Its great. I have 1″ polished china white marble hex on my new bathroom floor. Before using the shower, I cleaned and sealed the floor with a Solvent Based impregnator/Sealer. Over a couple weeks I put three coats in the shower area (I was waiting on the glass panel).

Now after three days of use areas are turning grey (like the “White Marble Gone Grey” question on your site); however this was pretty much white to begin with. It seems like moister is getting to the thinset. Did I use the wrong sealer? Do I need to pour it on thick to get it in to the grout since there is so much grout with a 1″ hex? Do I know need to wait for the greying to dryout before I reseal? Secondly I too have the same problem as with White Marble Gone Grey question. My walls are a 5″x2.5″ Polished China White marble. I waited a couple weeks to let the thinset dry prior to sealing and resolved at the time that there was going to be some tiles greyish and some more white. I sealed the walls and now I’ve read your response to the “Gone Grey” question. Have I forever sealed the moister in? Will it eventually dry out, albeit slowly? Could I apply heat with a salamander to draw the moister out of the tiles even thought its been sealed.

Thanks, David.

Hello David,

Basically the sealer is not working effectively in the grout but it is working on the marble. The water is soaking into the grout and wants to wick out the marble; however, the sealer is blocking the moisture from evaporating. I am sure that you probably guess this by the way it looks.

The problem is two-fold. First all, the sealer is probably a high viscosity sealer that is commonly used to penetrate the tight pores of natural stone. With non-sanded grout joints this works well as long as the grout joints are sufficiently sealed as well. However, with sanded grout (common with joints over 1/8″ wide) the low viscosity sealer just wants to suck down in deep in the grout and leaves the grout surface unprotected. You can test this by simply wetting the grout and seeing if it becomes darker. If it darkens, then the grout is not sealed sufficiently.

Secondly, grout joints, especially in mosaic patterns, are difficult to grout because they are slightly concaved from the marble surface. As you wipe on the sealer, you miss the grout surface. Combine this with a low viscosity sealer and you basically have no sealer on the surface layer of the grout.

For the fix, here is what I recommend. First you need to see if you can pull the moisture out of the marble by using a salamander heater or equal. It could take several hours and a few tries. Given that you have applied several coats of sealer, this might not work at all. In that case, you need to effectively decrease the volume of sealer in the marble. Do this by cleaning the surface with Acetone, sponging it on the surface and letting it sit there for about 20 seconds before wiping off. This should allow you draw the moisture out with the salamander heater. If the tiles do not turn back to white, then you have probably sealed the moisture in before the thinset or the grout fully cured. If this is the case, you need to try Acetone again and heat until the moisture mark are gone. You need to wait a couple days after they finally disappear because they will dry on the marble surface first, and then deeper. If you think they are gone, wait a couple days to see if a little more moisture wicks to the surface.

Finally, you have to re-seal the grout. I’d recommend using a higher viscosity natural stone sealer like Miracle Sealants 511 Porous Plus or equal. Don’t be concerned with sealing the marble, just focus on the grout. The marble mosaic will get covered if you just worry about sealing the grout. Watch for all the grout to darken from the sealer as you seal it to confirm the sealer has contacted it. The grout color will come back to normal once the sealer dries. Let is dry for 24 hours before use.

Best wishes!

My new marble countertop in bathroom has some cloudy spots in it. How can this be fixed and what causes this? Please help because I don’t know if it is my fault or if Contractor(stone) did not seal properly. I have only had them for a month. - Jerelyn

Hello Jerelyn,

The elegance of the soft deep brown background and while veining of the Imperator Dark marble that you have installed is truly beautiful. However, what you really have on your countertop is a metaphoric calcium carbonate based natural stone that must be sealed with a silicone/siloxane sealer in order to prevent acid chemicals from reacting with it. Common bathroom items such as hairspray, makeup, and even toothpaste contain small degrees of acids that react with Calcium Carbonate minerals. The result is microscopic etching due to corrosion of the stone. The only way to repair it is to re-polish it. The only way to prevent it is to seal the stone so that the acids are blocked. The dark color of the marble also accentuates the etching.

There are products that claim to ‘fix’ such dull marks and some are reasonable remedies if your expectations are not that high. Search, ‘Stone Care’ on Google and you should find a do-it-yourself product that you can order.

My wife and I are designing a pool which will have a planting area as a wall of the pool. The planting area will be covered with marble but we are not sure how the chemicals of the pool can affect the marble. If not marble what other durable choices we should consider?

Robert

Hello Robert,

There are several things to consider here. Some new pool systems clean the water without the need of routine Muriatic Acid treatments. If this is your design, then that eliminates one of the problems with using marble around pool areas. This acid is basic commercial granite Hydrochloric Acid. If your pool design requires this acid or any other acid that reacts with calcium carbonate (marble), then keep in mind that the acid(s) will literally dissolve your marble.

In addition, even sunlight and air pollution will noticeably damage the finish on marble within a year or two. If you do not desire an ancient weathered look, then do not use marble outside and especially not around water features that are designed to required acid treatments.

My recommendation is to use granite. Muriatic acid and sunlight will not harm granite at all. There are hundreds of colors that you can see on www.GraniteStock.com and I am sure you would find one that you like. Note, that a few exotic granites are coated with polyester resin at the factory. Do not use these granite colors outdoors because the resin will deteriorate and ‘yellow’ from sunlight. Just ask the supplier if the granite you like is resin coated or not.

Best wishes,
Tom Cordova

I purchased a bathroom vanity from HomeGranite.com a while ago and just love it. Hope you can help with a problem I am having with marble that I have in another bathroom on the shower floor with a honed finish & counters that are polished. There are some dulled spots on the polished counters where cleaning solution has left marks. On the honed shower, the finish has either come off or it is completely stained with white. Can you give me an idea of how to deal with this. May we call you and if so, a phone number please. Thanks for any help you can give - Bonnie

Hi Bonnie,

The marble in your shower and on your other countertop have been etched by the chemicals used to clean them. Marble is a Calcium Carbonate based rock which is sensitive to even mild acids and chemicals. You need to stop using those cleaners and have the marble professionally refinished if the damage is too aesthetically displeasing. Remember to use a penetrative marble sealer after the surfaces are refinished. My overall recommendation is to use a marble cleaner in the shower, then seal it after it dries. For the countertop, have it re-polished and then seal it.

Read my article about Maintenance and Cleaning for more helpful information.

Best wishes,

Tom Cordova