Marble Sealing - Before or After Grouting

I apologize for the basic question but my contractor insists on grouting the marble floors (18X18 polished Cararra) and then sealing at the end. I have read multiple sources that it can be done before and/or after. Are there any issues with sealing AFTER grouting? My concern is bleeding from the grouting.

 

After ensures that both the grout and the stone are sealed.

 

I could perform a 2nd layer of sealant. Yes, afterwards would ensure grout is sealed but then why do people INSIST on sealing BEFORE grout? I have read that polished marble shouldn't need to be sealed first. Is that because honed has a higher tendency to stain?

 

What's the reasoning for sealing before? The only one I can think of is if you go with a dark color grout.

Polished marble isn't as open was honed would be. I just installed honed marble and plan on grouting before I seal.

 

To remove chance of staining I believe. The product specifications state to seal BEFORE grouting:

http://miraclesealants.com/msds/s_511_porous_plus.pdf

 

Sagosto,

Let the contractor do it his way, he's right. The only reason to use sealer before grouting is as a grout release. As long as you don't select a contrasting color grout. (which you should never do), it'l be fine. He's using white unsanded grout, right?

I think you may have misunderstood what Miracle Sealants has to say in that link. Remember it's marble not ceramic tiles. They even say to clean with acid. Not a good thing with natural stone.

Jaz

 

Apologies for questioning everything but I have read such conflicting opinions on this from 1) You need to seal before, after, and then a few days later 2) seal BEFORE to avoid "seal haze" 3) seal afterwards (as in this thread)

I am nearly positive it is unsanded Bostik in "Silver Bullet" to match the marble.

 

That color should be light enough to not stain the marble from the edges. What does the contractor think? White is usually the safe bet.

Jaz

 

He insists that sealing should occur after grouting. I guess the only issue would be staining from the grout. He doesn't know what color I am using so I wonder why he has no concern. However, his best interests might not be my best interests.

 

As I said before, he's right. Seal after it's grouted and cured, per directions.

Why doesn't he know? He may have no concern perhaps because why would he think you want anything other than white? You need to tell him and see what he thinks. He's obviously assuming white. I would recommend white too.

Jaz

 

The white will stand out against the marble. that color blends in better. I'll tell him it is a more gray color to see if he thinks differently. You don't have any concern over staining during grouting (e.g. grout haze)?

 

This is what I said in #6 above.

The color you selected isn't contrasting, but it does have pigments. I'm not concerned about grout haze, that's a surface problem. It probably won't be a problem, but then again who's gonna guarantee that? It'l be on you if there's a slight staining.

The main staining would be from the edges, so you'd have a picture framing situation. That can be alleviated by sealing the edges prior to grouting. Lots of work and extra $$$ to you. We don't like to get sealer into the grout lines.

Jaz

 

Installer is confident no issue will occur while sealing after grouting. He also said he puts some sealant in the grout mix. Is that normal?

 

Depends on what he's using. Did he say, you ask? Almost all grouts today have a latex/polymer in the blend, so it could be one of the new miracle additives. Many people have had issues with some. It would be nice to know what he's using.

However, a sealant in the grout has nothing to do with what we've been discussing lately which is grout staining the tiles. Also, if he's adding a sealant in the grout, will the additional sealer applied later be ok? Is it all compatible with marble?

Jaz

 

With utmost respect for the knowledge and experience of the others posting in this thread, if'n it wuz my house, my floor and my money, I'd want to seal the tiles before grouting, then grout, remove any grout discolouration on the tiles, and then seal again.

The reason why I say that is because when I tiled my kitchen counter top, I chose a cream coloured mosaic tile and I grouted with a reddish brown colour grout. After that, I had a reddish brown cast to all my tiles, and I attribute that to the fact that the reddish brown iron oxide particles in the grout were so small that they got into the tiny surface roughness of the tiles I was using. If I had sealed that tiling first, that surface roughness would have been filled with sealer and that would have kept the grout from staining the tiles.

I can't see any reason why the same kind of staining wouldn't happen on a marble tile floor. I'm thinking that while it might be possible to remove any staining with acid, you don't want to use acid on marble. Marble is nothing more than compressed limestone, and just as limestone will be dissolved by acid, so too will marble. If you try removing any discolouration on the marble with acid, then you're going to muck up the surface of the marble.

If you seal the marble first, then at least you have a better chance of using acid to remove any grout staining on the tiles cuz of the thin film of sealer between the acid and the marble.

 

Nester, you used a reddish brown grout on textured light colored porcelain tiles. That's a completely different situation. Maybe you shoulda used a grout release product or not used contrasting grout.

No, no, no! Why are you bringing acid into this? You do not use acid on marble. Then you change your mind and think a sealed marble will prevent acid from hurting the stone? No it will not. For one thing, sealer does not stay on the surface, it's penetrating sealer, there's virtually none on the surface. But even if you used a topical acrylic finish, I'm pretty confident acid would do a number on that too.

Jaz

 

JazMan:

Well, all I'm saying is that without sealing those mosaic tiles on my counter top before grouting, I found that they were stained reddish brown after I finished grouting. The same colour as my grout. I don't know that a "grout release product" would have prevented that from happening since I never used one. All I know is that the tiles were stained after grouting, and at the time I was sorry I hadn't sealed the tiles on the counter top before grouting to prevent that from happening.

The purpose of this forum is for people to exchange their ideas, experiences and knowledge, and it would not be helpful to the OP if I were to keep silent about the problems I had with grout staining my tiles simply because it wasn't in agreement with what you were saying.

Regarding using a film forming grout sealer on the floor, I can assure you that a thick coat of acrylic film forming grout sealer will protect the grout and tiles from acid. I don't want this post to be unnecessarily long, so I'll tell you how I'm certain of that in a PS at the bottom of this post. You can read it or not, as you wish.

You're saying to use a penetrating grout sealer on a floor. I've always been told it's best to use a film forming sealer there, and I'm wondering if I was misled.

Penetrating grout sealers work by lowering the capillary pressure of the grout so that it doesn't wick up water the way unsealed grout would. By keeping the interior of the grout dry, mildew won't grow on the grout because of a lack of sufficient moisture. And, the fact that the sealer is right inside the grout protects it from erosion by the shower spray, and that makes it last longer than a film forming grout sealer. So, I couldn't agree more that that's exactly what you need in a shower.

But, on a floor you generally don't get enough water spilled often enough for mildew growth on the floor to be a concern. Maybe on the floor right beside a bathtub or directly under an uninsulated toilet tank it might be, but for most floors, especially a tiled kitchen or dining room floor, the bigger concern is soft stuff like peanut butter, ice cream, dog poop, cat barf and lemon merangue pie being mooshed into the porous surface of the tiles and grout and providing a food supply for bacteria as that stuff rots.

I could see how a penetrating grout sealer on the floor would prevent spilled liquids from being wicked into the grout, but I can't see how it would prevent soft foods, from getting mooshed into the grout and rotting there. Or, for that matter, how a penetrating sealer would prevent even household dust from accumulating in the porous surface of the grout and making it dirty and discoloouring it at the same time.

I can see how a film forming sealer (which I think you referred to as a "topical" sealer, just so we understand each other) would keep both the floor tiles and grout clean and free from stains and bacterial growth. So, I can't help wondering where the advantage would be in using a penetrating sealer instead of a film forming sealer on a floor? Or, at least, why would you use a penetrating sealer on a floor instead of a film forming sealer?

Sorry if these questions might sound dumb, but I expect I'm only asking what lots of other people in here are wondering about, but not daring to ask. Happens all the time.




PS: How I know that acrylic sealer protects my grout

I expect that I have a thicker coat of acrylic grout sealer on the grout lines in my bathrooms than the OP would put on his floor, but I find that a film forming acrylic sealer DOES protect the grout in my bathrooms from acid.

When I'm cleaning a bathroom in preparation for applying another coat of grout sealer to the grout lines, which I do every ten years or so, I paint a phosphoric acid based toilet bowl cleaner on to the tiles high up on the walls around the tub with a wide paint brush. I kinda scrub the tiles with that brush until they look clean-ish, and then I use a rubber squeegee to move the phosphoric acid into the grout lines. Then I use that same brush edge-wise to scrub the grout lines to dissolve the soap scum in those grout lines especially well. I work my way down the walls like that, always adding new acid with the paint brush to ensure effective cleaning. Then I use my carpet shampoo'ers water pump to spray the tiling down with water to wash the acid off with a spray gun. And finally I vaccuum up the water on the tiling and surrounding ceiling, walls and floor with a tool called a Taski Vertica wall squeegee that I connect to the suction port on my carpet shampoo'er.

Then, after allowing the wall to dry overnight, I apply new grout sealer to the grout lines. I do that by holding a trouble light and small container of grout sealer in one hand and an artist's paint brush in the other hand, and I can see by the way the light reflects off the grout lines that I'm painting the grout sealer over a smooth surface, not a dull rough one. That smooth surface is the surface of the old grout sealer. I know the grout wasn't dissolved by the acid because I would see something funny going on as I'm painting over each horizontal grout line, and literally inspecting every inch of horizontal grout as I do so. I can see that the acid isn't harming even the grout sealer because the surface of the grout sealer is smooth and hard. If the acid were harming the grout sealer, it wouldn't be as smooth and hard like it was just applied yesterday, but that's what I'm seeing. I wouldn't clean my bathroom ceramic tiling that way unless I was confident that I wasn't harming my grout.

I do concede though, that I have plenty of sealer coating my bathroom grout lines. The manufacturer's instructions call for one or two coats. I'm probably averaging about 7 or 8. But, the fact that the grout sealer doesn't appear to be in the least bit affected by the acid suggest to me that a thin coat of sealer would protect the grout just as well as a thick coat.

 

Nester,

I had written a reply to point out the things I disagree with you, but had to pause for a short time. When I continued, this forum's program asks you to login again at which time everything gets trashed. I'm not gonna waste more time on this.

Anyone that has specific questions can ask here or start another thread.

I recommend you try harder to keep your replies shorter, that way more people will read what you have to say.

Jaz

 

The marble is being laid down right now and the grey thinset is coming through from the bottom. I am not sure if that is due to the thinset or the moisture. Does that go away? Or is that staining from the bottom?!

 

Grey thinset? Why do have have idiots installing your floor? Where did you find them?

Jaz

 

OK, OK, I don't mean to blame you unless you searched all over for the cheapest price or?

It's obvious this person is not a tile setter, at least not a marble setter. Is he/she really a licensed tile setter or a contractor that claims to also do tile? Have him show you his license and/or look it up in the NJ database. What room is this again? The problem with small contractors often is that they have to do everything themselves, some of which they're not qualified or maybe know just enough to get by...................

Jaz

 

Master BA on 2nd floor. I didn't ask regarding color choice as a google search indicates it was by preference related to grout? Nothing jumped out. He is a license contractor in NJ with 15 years experience but that doesn't mean what quality. No, he was not the cheapest by far.

From other reading, it appears that it is moisture which will take days to dry to come to correct color. This is concerning.

 

Google didn't know you're using marble, light colored marble.

What is he licensed/qualified to do? Maybe he's a carpenter or plumber, that does't that make him qualified to set marble or do electrical?

Too late now but we never got to the subfloor requirements for marble over wood. Not the same as for ceramic. Ask if you wanna know more, but I hate to rub more salt.........

Moisture from the adhesive is part of it, but you do not use gray thinset, especially for light colored marble. You also need to butter the backs 100% before setting. Even with the correct thinset the tiles may stay dark/wet for weeks. With gray mortar, they will cure darker than they should be, I guarantee it 99%.

Jaz

 

And to add to it... there's a small space (less than 1") between the bottom subway tile against the wall and the flooring. Not sure how that space will get filled....

 

When that gap should be about ⅛" and it's 1"..........I wouldn't consider it small.

It'll easily get fixed when they rip out the tiles, add a layer of ⅜" ply, then new concrete backer and finally new tiles done right.

What's your plan now, did they continue or did you stop the work or? I'd like to know if I'm wasting my time and if you care about your home.

Jaz

 

I don't know to be honest. I'll talk it over with the wife. I guess it is possible that the darkness is from the moisture and it will "dry" back to the lighter color. I need to see it in the morning.

The tile was laid between 9:30AM and 4PM today. Is it OK to walk on in the morning?

 

So, you are not curious why I stressed that the subfloor system must be stiffer for marble than for ceramic? This would be the proper time to decide whether they also messed up in that regard. You must have a double ply subfloor + the joists need to meet higher standards. Cracked grout and tiles are not a good thing.

Gray thinset behind Bianco Carrara will darken the tiles even 3 years from now. They will lighten once the water evaporates, (1-3 weeks maybe), but not to the original color. Plus it sounds like these guys probably don't know what "buttering" means. Ask them, and if they say toast...............?

Flat footed, but I don't know how much you weigh. Put down some walking boards if you have to get on them.

What are the layers under the tiles again? Please name each and how thick. Which thinset again?

Jaz

 

Just have to say....Jaz is the man for tile! Do what he recommends if you want a quality job.

 

Sorry for the slow response. I have a newborn and it has been hectic lately especially with all of the snow. Overall, I think the floor came out better than I initially thought. I found a few issues such as the "opening" for the tub drain was cut too big so the trim piece won't cover it and one cut around the shower wall wasn't cut well. This was the 1" gap that I referred to but it was more like 1/4" I would guess. However, the cut is off as you can see from the pictures. I suppose grout can be used around the edge of the trim piece but not sure it would work for fixing that corner cut. What is the correct method to finish the trim piece? With regards to the cut around the corner of the shower wall, I am planning to ask him to replace it but concerned it will delay the project even further. The current plan is to complete the grouting on Monday and install the vanity either Monday or Tuesday morning. I assume he would install the vanity on Tuesday morning to give the grout 24 hours to dry before installing the vanity but I am not sure. He did say he would be careful to not touch the grout lines though.

The dark color on the marble was definitely moisture as it has lightened quite a bit. I am not sure why white thinset was not used nor did I even think to ask. I guess I will never know how much the grey thinset affects the overall color. Most of the tile was white but there were some gray in the lot. The subfloor is the existing 3/4" plywood and then a new 1/2" plywood (which I insisted on) and then 3/8" "hardbacker". Unfortunately, this caused another problem as the transition into the bedroom is too high due to the raised subfloor. You can clearly see the subfloor/marble threshold from the bedroom. Any ideas? What do you think?

 

More pictures of the bathroom including the shower.

 

Oh boy, there's a shower too. I wonder what's behind those tiles and how it was waterproofed.

Jaz

 

Any opinions on what you see so far?

The shower pan was installed by my plumber and it was a rubber mat and they were very specific about the pitching of it. The remaining shower was done by the contractor (tile guy) who used "wonderboard".

 

Well shoot! I wish I knew they made subway tile with the bullnose on the edge. That would have been useful for my project. Lesson learned!

Anyhow, that miscut tile at the corner of the shower is not acceptable. Make them replace it. I would like to see the shower drain issue you are talking about. Probably not acceptable either. You paid a lot of money for that tile and you should not accept garbage like that. Don't let your excitement to have your project finished let you accept substandard work. Tell them to do it right and withhold final payment.

The wonderboard should have a plastic sheet behind it or a waterproofing membrane on top of it.

Fit a piece of wood under the marble threshold and paint it the color of the door casing.