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Marble sealants


Jim Morrison
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Sealants are a double whammy. They seal as much water in the marble as out.

I know you understand the fundamentals of moisture migration in stone, but in my experience (which involves several thousand stone and marble showers), when it gets to having to "seal" the marble/stone, there's something else wrong.

What are your specific conditions that you're seeing, or is it just a general "hey, I oughta seal the marble" thing?

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Sealants are a double whammy. They seal as much water in the marble as out.

Kurt,

Would you recommend Not sealing marble (or travertine, porcelain, ceramic etc, etc) when installing? Or just when moisture has had a chance to penetrate the stone?

Reason why I'm asking; got a friend that's finishing out a basement bath, and while we are at it(Meaning mostly him, if I play my cards right), I'm probably going to start a little remodel at me casa. Getting a great deal on marble and other stone if we buy in bulk.

Frank

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First, I have polished marble in one of the baths at my house. I'd never install it again. It's beautiful but it's a maintenance nightmare. We squeegee the bath surround every time we use it, many cleaners etch it, hard water etches it, it scratches easily and it requires a semi annual polishing if it's used regularly.

Our main bath is all porcelain tile. It's maintenance free and nearly damage proof.

We maintain the marble with Bri Wax. We just use the porcelain.

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Kind of off the topic, but....

I don't know how many of you have been in a Marble Slab Creamery (Ice cream shop). They mix ice cream and other goodies on huge marble slab tables. I asked the owner of the one down the street from us how they keep the ice cream, etc from staining the marble. He said that about once a week they coat the slabs in a thin coat of food grade oil and then they buff it into the marble. Yes, it does darken the marble a little but it also keeps "stuff" from soaking into it.

Now, I don't recommend doing this to a shower floor. However it is something to think about.....

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Sealants are a double whammy. They seal as much water in the marble as out.

I know you understand the fundamentals of moisture migration in stone, but in my experience (which involves several thousand stone and marble showers), when it gets to having to "seal" the marble/stone, there's something else wrong.

What are your specific conditions that you're seeing, or is it just a general "hey, I oughta seal the marble" thing?

Kurt and Chad (and others),

Thanks for chiming in. I know you two have more experience with this than I do.

The marble in our shower is just stained and I know that the generic advice is that it should be sealed regularly (annually?). We have no leaks. Any advice you can give me that will convince Kelli that this is unnecessary would be most appreciated. Failing that, I'd love to learn whatever you two can teach me about this marble showers. As you might have already guessed, I'm a born and bred ceramic tile a sort of guy.

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For a few years in the early nineties I had a job that included making things from marble (sills, fireplace surrounds, counter tops etc) with very basic tools: buffer/polisher, grinder, wet saw and a belt sander. After spending about a week making a counter top from white carerra marble only to have the client complain after she spilled red wine on it I decided I don't care for marble.

We would use marble sealers (can't remember the name) but they weren't terribly effective. The only really good way I found to keep marble from staining was to keep it away from people.

-Brad

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Well, marble is one building product that I've never worked with. However I have had an experience with it. When I was a kid, our neighbor, who was a builder, had a slab of marble leftover from a job. He didn't need it, so he gave it to us. We didn't really need it either but, what the heck, it was marble. So my dad stacked two pair of concrete blocks in front of the couch in the family room and set the marble slab on top of them to make a coffee table out of it. Our neighbor told us that it would stay clean as long as we never tried to seal it, so we didn't. He warned us that, if we tried to seal it, it would stain. It was just ground flat and, at one time must have been polished but we never put any kind of sealer on it.

That thing got everything imaginable spilled on it and nothing ever stained it. We spilled all kinds of food on it, put our grimey feet on it, did homework projects on it, and nothing ever stuck. Wine, tea, grape juice, you name it.

Maybe it was special marble.

- Jim Katen, Oregon

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It very well may have been "special" marble.

Stone is strange stuff. There are porosity and absorbency differences between various sorts of stone, and sometimes vast differences. Marble has several grades and there is a definite grain to marble with some portions of marble being highly absorbent and other areas of the same slab being reasonably resistant to staining.

Sometimes stuff will soak into stone, then dissipate into the mass of the material and stains will "disappear". Sometimes stains will sit there for a hundred years. I've seen hundred year old marble in downtown buildings that's stain free, and other brand new marble in fancy pants bathrooms that soaks the oil out of the wax ring on the toilet flange, tinting the flooring around the toilet a nice midlife turd brown.

Little known to the masses, some marble, particularly travertine, is flooded and filled with a polymer material; if it wasn't it'd soak up anything and everything that touched it. If you look at travertine, you'll see pockets of uniform color; that's polymer filling up the huge voids that naturally exist in travertine. Travertine is crap, and it's held up as groovy stuff, but anyone that knows stone knows it's cheap crap, made usable with polymer.

Sometimes that nice shiny surface isn't even marble; it's buffed polymer. All those Vegas motel rooms with the shiny marble are likely polymer coated stone.

One of the reasons I wouldn't ever eat any of that marble slab ice cream stuff is the marble holds bacteria. The goons putting food oil on the marble and then "buffing" it, don't even realize they're creating a wonderful little mess of bacteria and then holding it in with the oil. Read any of the readily available information on food prep surfaces, and I bet you'll never eat that ice cream again.

Back to showers.........

Marble sucks for bathrooms, including showers. It soaks up body oils, soap residue, conditioners, and since it's Jimmy, Lord only knows what else he's spraying around in there. I'd probably want to flame sanitize the place before soaking it in biocidal agents and powerful surfactants, but I digress......

If it's the average marble, sealing it isn't going to do squat. It'll still stain. I don't care what you put on it. The folks that like sealers the most are the folks that manufacture and sell it, and the goofy interior design types that don't know anything beyond the square foot cost of the stuff and the fact that it's currently fashionable.

Read the label on any of the stone sealers. The fine print always says you have to reapply every couple weeks. Who's going to do that?

Unless it is a high tech modern sealant like silane or siloxane (which chemically reacts with silica to create a resin in the stone), the sealant is going to disperse into the stone just like any other material. Even silane and siloxane have reduced performance with each successive application because the silica that is necessary for the chemical reaction to occur is coated with the resin from the previous reaction. Surprise, all you folks that think sealing masonry with siloxane is the answer, but again, I digress.......

Tell the beautiful woman there's no particular answer for the conundrum of nastified marble shower enclosures. You can try all the sealants you want, but all they're going to do is seal in the stains, and it's an endless cycle of applications ending in frustration and wasted money, not to mention preserving the Jimmy spore in places it shouldn't be.

Porcelain, aka vitrified surface material, is the answer to sanitation and appearance concerns. Marble, while visually beautiful, is a complicated material that needs very careful selection and grading for specific uses (something it never gets), and I'd never use it in a bathroom.

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Yes, it does darken the marble a little but it also keeps "stuff" from soaking into it.

No it doesn't. Check out the porosity and absorbency characteristics of stones and marbles. If it'll soak up food oil, it'll keep soaking up whatever else is placed on it, including the dairy product in the ice cream.

This is folklore, just like the folklore of putting oil on your cutting board, or any other wooden kitchen utensil. All it does is soak the material in increasingly rancid oil.

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Mineral oil doesn't turn rancid, vegetable oils do. The only food prep surface you should put veggy oils on is cast iron.

As for the Jimmy oils...blech! [:-yuck]

Back on topic...

I used a spray on sealer for the glass mosaic tile in my kitchen, I don't recall the name but it came from Lowes and was specifically for stone tile, it was the only one that said it was safe for use on glass tile. Comes in cans like spray paint and is pretty smelly so ventilate well. It worked well on my tile, and it's cheap and dries fast, so if it's a waste of time and money it's only a little of each.

Tom

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It's 16 square feet of mosaic tile on the countertop, that means lots of grout in the food prep area.

Tom

Which is really the only thing you ever need to worry about sealing. Grout.

Jim, unless your going to power wash your vertical shower walls with wine, I'd say the link Dirks posted, has some useful info.

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From someone who sees historic marble architectural details fairly frequently and has been to some of the most incredible marble quarries, here's some things to to consider:

Marble was once limestone. Under intense heat and pressure, the crystalline structure became very tight, so there is very limited porosity. Properly polishing marble has virtually eliminated porosity. Polished, real marble will not stain, unless something acidic has attacked/dissolved the surface. Marble that came from dolomitic limestone was most often chosen for exterior details as it is more resistant to acidic contaminants than marble from calcite limestone. If there are stains on real marble, its due to loss of polish or the stains are only *on* the surface as a crust or by static attraction.

By the latter part of the 20th century, what's being sold and installed as marble often isn't the same material as the real marble seen in the historic buildings. Here's the ugly truth - many types of stone (that isn't a granite) that can be cut smooth and take a certain polish, can be called marble. That's right, a highly polished petrified mammoth turd can be sold as marble. When purchasing from a supplier, be sure to get authentication from the quarry, that it came from the correct spot in the earth to be true marble.

The problem of stains and idea of using sealers came about recently when folks started putting these polished rocks in their kitchens and used them as working surfaces. Um, many foods and beverages that are now contacting these surfaces are VERY acidic, resulting in loss of polish and allowing stains.

Working with a couple conservators in the UK, who are trying to protect historic, architectural marble and other unglazed masonry from potentially acidic pollutants, penetrating sealers are sometimes used (in very specific situations). One product name I've heard is Lithofin,

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There is almost no real polished marble being used in contemporary projects. It's all resin or polymer treated stuff; nice and shiny, but it isn't polished stone, it's plastic.

The few bits of historical architectural marble I see are astounding materials to see and touch. They are also never used in bathrooms or kitchens, only in decorative columns and details.

I did a house in Kenilworth about 10 years ago, built by the fellow that was the marble importer during the late 19th and early 20th centuries for Loop office buildings. The whole house was full of the good stuff, polished, and essentially in perfect condition. None of it was in bathrooms and definitely not the kitchen. He put ceramic and porcelain in those rooms.

Modern cleaners and atmospheric pollutants are the death of real marble.

Bathooms are kitchens are full of cleaning agents and "pollutants". Marble doesn't work in these locations.

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I was relating my experience in seeing the few architectural marble components remaining in my market. The sentence preceding the quoted one referred to what I see. I never see them in the bathrooms or kitchens. I guess I wasn't clear that this was my experience. The idea could have been related more clearly.

I don't know what you see.

The marble sinks I see are in the architectural artifacts warehouses, and they're invariably stained, pitted, and in poor condition, which is why (I think) many folks took them out.

On reflection, I do recall seeing a few sinks in completely bombed out crack mansions on the West side of Chicago, and a maybe a few more in rundown properties scattered around. The fixtures are mangled and stained (like the houses), the result of them being used in bathrooms and then neglected like the rest of the house, or so I suppose.

I'm sure there are marble fixtures still in use somewhere that have been maintained.

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