Why are there stains on new limestone floor?

Q. I bought lagos azul limestone back in December and it is getting installed in sections. I would greatly appreciate it if you could help me. I am hoping you might know a solution or can refer me to someone. My kitchen contractor installed the tile in the kitchen and laundry in January. The rest of the tile is destined for our long hallway which is scheduled for install in a couple of weeks. When they installed the kitchen tile, for some reason they did not seal it at the time. The contractor put that brown paper over it during the rest of the construction process. When we uncovered it when the kitchen was done I noticed the tile was not sealed and that some of the tiles seemed to have stains on them. I thought it was something from the construction process. I also thought maybe they would go away when we used the sealer. But actually the stains seem to be getting bigger and spreading. It almost looks like an oil stain. So now I think it has something to do with minerals and moisture from the cement floor. Our house is built on a slab on the ground -- no basement or anything under it...plopped right on the cement basically. So we decided to try a matte sealer with color enhancer which would bring out more of the tile color thinking that would help too. It got sealed yesterday and it does help a bit but the stains are still very noticeable. It actually seems like the sealant did not get absorbed where the stains are. OK. My question: 1. Since we have a huge hallway to do next, is there some kind of sealant we can use on the concrete before we install the tiles there? My contractor said that would not work as the thin-set needs a rough surface to adhere to. But he is not a tile expert so I am hoping there is some way to do this. Any suggestions? 2. If there is a concrete sealant we can use I assume that I could have them pull up the tiles in the stained area, seal that portion of the floor and then install new tiles. I think I over-ordered enough to cover that but we will see. 3. Can I fix the stains or should I just replace them??? Thanks so much for your time. I really appreciate it. Sincerely, Paul 

A. Considering the length of your question, we've broken it down in sections... 

I bought lagos azul limestone back in December and it is getting installed in sections. I would greatly appreciate it if you could help me. I am hoping you might know a solution or can refer me to someone. My kitchen contractor installed the tile in the kitchen and laundry in January. The rest of the tile is destined for our long hallway which is scheduled for install in a couple of weeks. When they installed the kitchen tile, for some reason they did not seal it at the time.

That was the right choice for your stone. You do not want to apply an impregnating sealer to a brand-new installation. You have to wait for at least 2-3 weeks, to allow the setting material to dry at its natural speed.

The contractor put that brown paper over it during the rest of the construction process. When we uncovered it when the kitchen was done I noticed the tile was not sealed and that some of the tiles seemed to have stains on them. I thought it was something from the construction process. I also thought maybe they would go away when we used the sealer. But actually the stains seem to be getting bigger and spreading. It almost looks like an oil stain. So now I think it has something to do with minerals and moisture from the cement floor. Our house is built on a slab on the ground -- no basement or anything under it...plopped right on the cement basically.

You're right about that. I highly doubt that the construction paper created those stains, considering that they are growing. The fact that the floor was set on a cement slab without the provision of a water-proof membrane is the culprit. It's easy to understand that there's not much that can be done now.

So we decided to try a matte sealer with color enhancer which would bring out more of the tile color thinking that would help too. It got sealed yesterday and it does help a bit but the stains are still very noticeable. It actually seems like the sealant did not get absorbed where the stains are.

And the more you will apply sealers to your stone, the worse the situation is going to become. Besides, what kind of sealer are you talking about? Sealers for stone are strictly below-surface products. What has a "sealer with a matte finish" got to do with all this?? We're not looking at a hard-wood floor, are we?

OK. My question: 1. Since we have a huge hallway to do next, is there some kind of sealant we can use on the concrete before we install the tiles there? My contractor said that would not work as the thin-set needs a rough surface to adhere to. But he is not a tile expert so I am hoping there is some way to do this. Any suggestions?

While there's nothing that can be done in the area already installed, this side of ripping the floor out, you want avoid the same mistake that was made so far. You do need a water-proof barrier.

2. If there is a concrete sealant we can use I assume that I could have them pull up the tiles in the stained area, seal that portion of the floor and then install new tiles. I think I over-ordered enough to cover that but we will see.

Try to get your money back. The sealers you've got are totally inappropriate to water-proofing the concrete slab. You need an actual membrane, not something in a bottle.

3. Can I fix the stains or should I just replace them???

I already answered that. To find a professional stone and tile restoration contractor in your area, contact us.