What caused my limestone tile to develop a yellow/brown stain along its edge?

QUESTION

Hi, I have limestone laid on new concrete last year and this year some edge around the grouting area turn brown or yellow. I have someone professional using efflorescence cleaner to clean and it’s still there. Can someone tell me what is it?

ANSWER

ANSWER -  Normally if you have a  yellow/brown rust-like color stain it is due to a combination of the stone being subjected to excessive moisture and due to the presence of metal, or that the limestone contains the ferrous oxide mineral.  It is not uncommon for natural stone to contain ferrous oxide or other metal based minerals that under a wet environment could lead to staining.

There are stone poultices that can be used to remove these stains depending on the source of the stain and how long it has been present.   You can normally purchase these poultices through companies who produce stone sealers and cleaners or you can hire a professional stone restoration company to attempt to clean it for you.

43 thoughts on “What caused my limestone tile to develop a yellow/brown stain along its edge?

  1. Andrea Kokinakes says:

    Hi, we have a white lime stone back patio with the yellow/brown rust stain spots. What can we use to get these spots out? Trying to clean then seal patio. Help!! 🙂

    • Donato Pompo says:

      Rust stains in natural stone is one of the hardest stains to remove. Many types of natural stone naturally has iron oxide minerals within it and if the stone is subjected to excessive moisture it can develop rust stains.

      If there is a metal material in contact with the stone and subject to moisture it can develop stains. If there is metal in the stone substrate that can develop stains.

      The superficial rust stains on the surface of the stone can be easy to remove, but underlying metal causing rust can be difficult to remove.

      There are some products on the market off the shelf that are rust removers for natural stone. You can experiment with those by doing an out of the way stone to see if it works satisfactory. You can buy poultices for removing rust stains. You can hire a professional stone restoration company to clean and seal the stone and they can attempt to remove the stain.

      • Dina Merritt says:

        I have the same stains on my porcelain pavers in my lanai. I removed all polymeric sand in those spots and cleaned the stains. Now I don’t know why it’s happening or what to do. Can you help?

        • Donato Pompo says:

          If you are using polymeric sand then I assume this is a sand set installation system. If so there should be at least 4″ of compacted base with an inch or two of sand where the tile is compacted into it. Normally the polymeric sand is then vibrated into the paver joints. I have seen with natural stone that the underlying sand or marble dust has contaminates that migrate up through the stone, but this should not happen to an impervious tile.

          If you have a true porcelain tile then it’s absorption should be less than 1/2 of 1 percent (<0.05%) which is considered impervious. If you have a glazed porcelain tile then I would not expect it to stain. Unglazed porcelain tiles can stain depending on how it was manufactured. Even though it is impervious there is off-gassing where small particles can get trapped in these candy-kiss configured pores and can be difficult to remove. The polymeric sand is a dry latex based material, so that should come clean. You might need to use some poultices to dry to draw up the stain. If you don't know what caused the stain then you have to test trial by error.

  2. Amber Schrimsher says:

    We had travertine laid for our new pool deck and covered patio. Within a week the travertine under the patio started to turn yellow. They laid our travertine on top of old pavers but told us that wasn’t the issue. They have come out several times to “treat” the stone but the yellow always returns. Then they came and removed the pavers and poured a concrete slab. They laid the same travertine and now the yellow has turned almost brown, it is much worse. They are now trying to tell me that it is a natural stone and there’s not much else they can do. We paid a lot to upgrade to travertine and it looks awful. I was just hoping there was something I could say to them to make them fix it.

    • Donato Pompo says:

      Recently I worked on a large residence that had Iranian Titanium Travertine installed on the exterior walls of the house that sits on the ocean bay. They developed yellow like staining. They were able to remove it with a phosphoric acid solutions but it bleached the stone and kept returning.

      We performed laboratory testing and found an abundance of invisible soluble manganese in the open voids of the travertine stone. When the stone is subjected to moisture the soluble manganese migrates to the surface of the stone and becomes oxidized by the damp ocean surroundings that converts it to an insoluble manganese that turns yellow.

      Whether or not this is your situation, we would have to investigate it. The industry standards for travertine states that Travertine shall be free of minerals that may cause objectionable staining under normal environments of use.

  3. David says:

    This is a very helpful thread as I’m seeing similar issues with my travertine on my pool deck. The edges are yellowing on certain stones and noticed it more after a major rain. I chose not to seal it as I prefer the dry look and like the travertine to absorb water on the pool deck. It seems like it is pretty easy to clean out, just takes some elbow grease. Anything I can do to prevent this? Is this a similar issue of iron oxide?

    • Donato Pompo says:

      Travertine is normally fairly dense and should not have a water absorption greater than 2.5% and can be less than 0.5% absorption that would make it impervious.

      We normally recommend sealing the stone. There are sealers called penetrating sealers that doesn’t change the color. There are enhancer sealers that will give the stone a wet look. Although sealers on exterior stones normally need to be reapplied at least annually. Sealers do make it easier to clean the stone because the sealer acts as a bond breaker and keeps moisture out of the stone.

      It is normal for stones to contain various minerals like iron oxide that can cause a yellow stain. Water is the medium that transports the minerals and precipitates the minerals that can cause the stains. So if you can keep the water out of the stone, both from the top, bottom and sides then that can prevent the staining.

  4. Andrew D Lonabaugh says:

    Amber, I am so glad i came across this post. I hope you were able to find answers to your problem as we are going through the exact same thing. We had shell-stone placed around our pool and in our covered lanai. Everything by the pool is fine but similar to you all the pavers under the covered deck are turning yellow/brown. Were you ever able to resolve your issue?

  5. Katie warren says:

    I just laid a limestone path next to a limestone wall that is and.
    The new stone is a brilliant white and looks awful next to the wall.
    What can I easily do to soften the harshness of this white stone.

    • Donato Pompo says:

      If you installed the path limestone directly over soil then the limestone will likely change colors over time as it absorbs the moisture and the minerals in the soil and stone.

      There are sealers that are enhancers that will give you sort of a wet look that might help. In theory, depending on the absorption rate of the limestone, you can stain the limestone if it absorbs. There are sealers that are meant to stain concrete that might work, but it will wear over time.

  6. Deb says:

    I too put shell stone in our lanai and around the pool. The worst rust staining is in the uncovered part of the lanai but still some in the covered part. My builder has put 50% bleach on it and it works to get rid of it but it comes back. Builder said it will go away once we have rains. Doesnt make sense to me. I dont want to battle this constantly, should we replace it. Builder said it came from the quarry in Turkey 6 months ago and hasn’t seen sunlight-also why it is rusting…??

    • Donato Pompo says:

      Shell Stone is a relatively weak and porous limestone with fossilized shells encapsulated within it. It is popular in some Florida beach areas, but tends to degrade and develop microbial growth due to its porosity and open pores.

      The rusting might have to do more with how it was installed rather than due to the tile itself. Often staining is due to the stone being subjected to excessive moisture possibly due to the lack of waterproofing, slope and adequate drainage. If there is any metal below or adjacent to the stone that can cause rusting.

      There are other types of brown staining that can come from other conditions. There can be soluble manganese that leaches to the surface and oxidizes turning a brown color.

      I doubt that the stains will go away by themselves. You need to determine what is the source of the staining so you can determine how best to remediate it.

      • Shane says:

        Hey, what a great thread! I’m currently cleaning outdoor travertine tiles which have developed an almost brown paint/ stain looking coloring along the wall and step by the pool on a certain side of the pool deck which is on the beach. I’ve cleaned the deck with multiple chemicals which got everything else out minus this stain? Can you help?

        • Donato Pompo says:

          Travertine tiles are very dense and can range from less than 1% absorption to 2.5% absorption so it normally doesn’t readily absorb. The first thing is to try to determine if the stain came from something on top of the stone or is it migrating from the bottom of the stone or did it develop within the stone.

          The stains coming up from under the stone is almost impossible remove. Often it is because there is some metal below the stone that has oxidized causing a rust condition to migrate up through the stone.

          For surface stains you need to determine whether it is a organic stain or an inorganic stain. There are poultices, which are compounds of absorbing material, that can be prepared and applied over the stain to pull up deep stains.

          I have seen in a Persian Travertine where it naturally had organic manganese minerals within the voids of the travertine that migrated to the stone surface where it oxidized making it an inorganic stain that cause a yellow/rust kind of stain. The house was right on the Ocean so that perpetuated and intensified the oxidation of the stone. The temporary solution was using a special acidic mix and it would take it away, but it tended to reoccur.

  7. Iris says:

    Very informative post. I see that with limestone pool coping there is a good chance of it discoloring where it meets the water. What about bluestone for pool coping? Will that discolor over time as well? Thanks.

    • Donato Pompo says:

      Any natural stone at a waterline doesn’t tend to hold up well. Water is constantly condensing and evaporating over it so it tends to develop a calcium build up. Plus if water is getting behind the stone, depending on how it is installed, it then has water migrating through it further leading to the surface of the stone spalling/degrading. Bluestone is a type of sandstone and it normally doesn’t hold up well to excessive moisture conditions. Better to use a porcelain ceramic tile that looks like stone that is easier to maintain.

  8. chris lazzaretto says:

    Hi,

    We recently installed a black limestone floor in a bathroom. When we were finished with the project we had cleaners clean the floor, I’m not sure what product was used. It now looks like there’s little white/tan specs in the surface of the stone. Any idea what this may be and what the solution would be?
    Thanks!

    • Donato Pompo says:

      limestone is a sedimentary stone found on ocean floors. Often it has fossils embedded in the stone so it could be a fossil that you didn’t notice before the floor was cleaned. If the cleaner was a strong acid, which most retail cleaners for floors are not, it is possible it bleached or etched the surface. In theory if it is just a surface condition it can be refinished to remove it. But if it is just an inherent characteristic of the stone it can’t be removed. Being a natural product every piece can vary in its physical properties to some degree.

  9. Chris says:

    Thank you very much for the quick response and all the Info! I came to realize that the material that was laid is a black limestone basalt. We’ve tried many different options to get the white spots off and we don’t see a solution. After reading more about basalt I am hearing that this material is very porous and that the back of the pieces should be sealed prior to installation so that the thinset does not suck up into tile and cause the minerals and salts to expose themselves on the surface. Does this sound right?
    Do you see any other solutions to on fix the problem other than remove and replace?

    Thank you!

    • Donato Pompo says:

      Limestone and basalt are entirely two different geological types of stone. Limestone is a sedimentary material from ocean floors and basalt is lava from volcanos that cools. Basalt is a igneous rock commercial known as granite. Unfinished basalt does have a lot of pores, but is generally impervious material.

      You should never seal the backs of stones. Sealers are normally bond breakers. There are a few companies who sell sealers and recommend it to be applied to all sides of a stone, but require a very high strength adhesive to compensate for the sealer. You want the adhesive to both mechanically and chemically attached to the substrate.

      We do recommend installing a tile liquid applied waterproof membrane that meets ANSI A118.10 over the concrete substrate that you then adhere the tile to it. This helps prevent moisture migration and efflorescence in the stone.

      I think what you more than likely have are what we call inclusions of other minerals in the stone that are natural. I think you should just enjoy the natural variation of the stone rather than wanting it to me monochromatic. Unless you do have clear evidence that it is an unnatural stone of some sort.

  10. Chris says:

    Thank you again for the information, it’s been very helpful.
    Is there a way I can send you a photo of what the stone looks like so you can get a visual and see what the “issue” is we are dealing with. If it were mine I would leave it, but the homeowners do not like it.

    Thanks again!

    • Donato Pompo says:

      There is no way to upload photos on this free forum. Photos won’t tell us what we would be looking at. If you need to further understand the condition then you will have to pay someone like CTaSC for doing the forensics, which may or may not be practical for your situation.

  11. George says:

    Hi,
    I’m in Florida and just laid Ibiza white marble (6x24x1.25) down for the pool deck. We had it sealed with an oil based sealer. It’s been a few weeks and I’m getting a lot of rust stains coming through. I understand that is from oxidation of the iron deposits in the stone. I was told the sealer would prevent this? Any suggestions since I’ve read it could be a variety of reasons from type of setting material used to not sealing and letting the iron deposits in the stone work themselves out. Thanks

    • Donato Pompo says:

      Generally speaking when you get rust stains it is because the stone is being subjected to excessive moisture. This often is because of how the stone was installed. The moisture is likely coming form beneath the stone. Sealers do not waterproof the tile and they don’t last that long. As long as the water beads up on the surface of the stone and doesn’t leave a wet spot after wiping it up then it is sealed. But that doesn’t prevent water from migrating through the grout joints or being trapped beneath the marble.

      • Deb says:

        Hello. If you seal the top of the limestone but the rust spots keep coming back then it was how it was laid? How should it have been laid to prevent this? Ours was just right on the fill for the build site. We have a huge pool deck we upgraded to limestone because they said it was maintenance free but we are battling rust stains non stop. Thank you for any information you can provide

        • Donato Pompo says:

          If the limestone was installed directly in contact with the grout then that is not how it should be installed and you are likely going to continue to have the same problem.

          The best way to install stone on an exterior deck is to put down a vapor retarder and pour concrete over it. Then put a mortar bed over the concrete to establish a slope and then waterproof the mortar bed and adhere the stone to it.

          There is a sand set method where the ground is dug out about 6 inches or so and then compacted. Then a 4″ gravel base is installed and compacted and then a 1″ sand bed is applied and compacted and then about another 12″ or so of loose sand is applied and the stone is beat into place. The surface of the stone has to be sloped 1/4″ per foot to a drain.

  12. Steve says:

    We just finished a pool remodel, which included an ivory colored Travertine stacked stone negative edge waterfall. My intent was to seal it before restarting the pool 2 days ago, but circumstances prevented it. Pool water has since contacted it and dulled the color very slightly. We’re prepared to live with it, but wondering if there is a product, retail or homemade, that could restore the original color? Oxyclean? Or would you recommend just sealing it when completely dry? Also, is Impregnator 511 Sealer a good choice in our application? Thank you for any assistance.

    • Donato Pompo says:

      Whenever you use natural stone in a pool or other water feature when it isn’t fully submerged it can lead to the stone surface degrading to some degree.

      You can’t seal a stone unless it is fully try or trap moisture in it. Sealers are only temporary and in water applications they don’t last that long. You can always restore the stone at a later date to look like new, but you have to drain the pool down to some degree so it is dry, but the condition will reoccur.

      Impregnator 511 is a good product, although I don’t know if it is suitable for a submerged application. There is a product manufactured by Prosoco called Natural Stone Treatment is a modified siloxane water repellent developed for limestone, marble and most other traditional masonry surfaces that is suppose to be a longer lasting sealer. You can find a link to their website on our Cleaner and Sealer Resource page at https://ctasc.com/category/resources/cleaners-sealers/

    • Jim Andrzejewskj says:

      Donato, you seem very educated on travertine pavers. Question, my contractor laid stone, the. Rebar, then about 4” of concrete then applied the travertine pavers to a mortar mix and placed on top of concrete bed. Admittedly, my pool contractor was leery of my stone contractors method being in the northeast (Pennsylvania). I sealed it with an impregnating sealer (Stain Proof Dry Treat) after installed last year.

      However, just this year a lot of the travertine is turning green in the veining and on the edges. I contacted the travertine supplier who provided a oxy cleaning agent that did not remove the green. I also used “wet and forget” which also was unsuccessful. Have you ever heard of travertine turning “green”. Algae and or mold come to mind but I would’ve thought the cleaning methods and/or power washing would’ve gotten rid of it but no such luck. Everyone (stone contractor, pool contractor, travertine distributor) seems to be baffled and Google is of no help.

      Any insight would be fantastic and much appreciated.

      • Donato Pompo says:

        I assume this is an exterior application. There should have been a varpor retarder laid over the ground first the the rebar suspended up at least 1/3 the thickness of the concrete. The concrete surface should be sloped 1/4″ per foot to an area drain or a trench drain. I would have specified to apply a waterproof/crack isolation membrane over the concrete or mortar bed, if there was a mortar bed over the concrete slab. The membrane should be sloped a 1/4″ per foot towards a drain or drainage area. Then you bond the tile to the membrane per industry standards.

        Interesting that Stain Proof Dry Treat now is called Premium Impregnating Sealer. Of course no sealer is stain proof. As they state on their website it is only stain proof if stains are cleaned up immediately.

        Regarding the travertine stones turning green, normally if you have a low spot where water is collecting, and not draining away, you can get microbial growth. But as you said, normally that is a surface stain that can be cleaned.

        Last year we did perform an investigation on what was called an unfilled Titanium Travertine from Iran that developed a yellowish stain. Our laboratory testing showed that the open voids of the stone contained a soluble manganese mineral. When the stone was subjected to moisture the mineral dissolved in the moisture and migrated to the stone surface where the moisture evaporates. As the moisture evaporates it precipitates the manganese mineral, which as it oxidizes from exterior environment it converts to an insoluble manganese and turns yellow. A diluted acid solutions temporarily removed the stain, but it would return. They hoped that eventually the soluble manganese would deplete and the stain would not return.

        You should hire an experienced and knowledgeable stone restoration company to experiment to see if they can clean it. It is possible to take a sample of a stained stone and have it evaluated chemically in a testing laboratory to identify the chemistry of the green material.

    • Donato Pompo says:

      If what you mean by your ground has turned into a swamp is that it is saturated with water then there isn’t anything you can do to remediate the problem without it returning. The nice thing about natural stone is you can restore it in theory to it original condition by grinding the surface down and re-honing or polishing it. But if the stone is constantly saturated with water I am not sure if you can adequately restore the stone. Travertine is very dense, so applying a stain to is will not adequately absorb it. If the stone is wet, then paint won’t last either. Unless you isolate the moisture from the stone or from a new product installed over it, you will continue to have problems.

  13. Seref Tastan says:

    We have a limestone application we used (Freska and Myra ) limestone Pavers outdoor. After a while and some rainfall , it seem to be leaving behind on the surface chalky almost white sand like substances all over and the home owners are insistent the stone is crumbling and deteriorating . We explained its due to the moister and mineral within the stone being pushed out and should go away after a awhile. Do you happen to know if this is correct information and what exactly that white chalky/sand like substance is?

    • Donato Pompo says:

      It is normal to have maybe a little efflorescence staining (mineral migration), but if it is excessive and if the stone is deteriorating/spalling then that suggests the limestone installation is being subjected to excessive moisture.

      When you have excessive efflorescence and the stone is deteriorating then likely the limestone installation either wasn’t designed correctly to evaluate water or it was not installed correctly resulting in the stone being subjected to excessive moisture.

      • Seref Tastan says:

        Lastly would you recommend us to seal the surface of the stone , with an impregnator sealer to try and help? Were familiar with efflorescence , but I have never ran into a situation like the one I’m having now , its literally white sand like mounds all over the surface.

        • Donato Pompo says:

          What you describe sounds more like the limestone is degrading, which we refer to as spalling. If it is spalling or efflorescence, and it is that excessive, then that is a symptom of a problem. The problem is the stone is being subjected to excessive moisture; likely due to how it was installed.

          Sealing the stone is only treating the symptom and doesn’t treat the problem. Sealing the stone might slow the degrading down, but it is only temporary.

          The only way to fully understand what is causing the problem is to perform a forensic inspection and investigation. It likely would require to perform some laboratory testing to evaluate the stone and the mounds of stone. We can determine what caused the problem and we can determine if it is repairable or if it needs to be fully replaced and respectively specify how to do repairs or replacement. This process is not cheap. If this is practical then go to https://ctasc.com/ctasc-services/forensic-failure-investigations/ to learn more about our forensic services.

  14. Victoria Saavedra says:

    I’m having an issue with orange rust like stains , which seem to be appearing from beneath my limestone like its being pushed through from beneath, We were able to wash away and clean it out , but it has returned over the weekend after we got some rain fall. We did use a sand base and were hearing that its the sand affecting our stone and that it should eventually go away . Is this information correct , what can it be that’s causing this? Also do you have any recommendations as to how this should be installed other than a sand base?

    • Donato Pompo says:

      Limestones can container iron minerals that when subjected to excessive moisture may lead to a rust staining.

      Also we have seen where stone installed in a sand base or marble dust base can lead to different types of staining if the sand/dust is contaminated with certain minerals. The sand might be natural, but its source may contain iron minerals that will lead to staining migrating up through the stone, if the stone is porous enough.

      If there was metal imbedded in the sand it could develop rust if it is being subjected to excessive moisture and over time it could migrate up through the stone. Since it is a sand set stone, I would remove it and look at how it was installed. Maybe there is a void that collects moisture, or maybe there isn’t adequate drainage under the sand as there should be a 4″ gravel base for drainage.

  15. Elizabeth Reimertz says:

    I had Myra beige tumbled travertine installed around my pool. I am getting rusty looking stains. When it rains thry disappear. When it’s dry and sunny thry reappear. I clean it with baking soda and water. It does remove the rust stains but it does reappear. The communiy sprinklers are also wetting them. Will the rust ever just run its course and stop? Suggestions?

    • Donato Pompo says:

      The travertine stones naturally contain soluble minerals, which some are iron minerals such as iron sulfide. Travertine is quarried all over the world and in USA. So depending on the source of the stone and where it is extracted within a quarry it may have more or less of those minerals.

      Normally the staining doesn’t occur unless the stone is being subjected to excessive moisture either because of how it was installed and/or due to the environment and how often its is washed down or that they are subjected to overspray from sprinklers. You should ways adjust sprinklers so they do not get the stone wet.

      I don’t think you will ever run out of those minerals in the stone, but you can use various types of sealers to help minimize the staining. There are different types of breathable penetrating sealers that do and don’t enhance the stone that will vary how long they last, but you should expect to reapply the sealer every year or so.

  16. Sar Long says:

    I have a brand new limestone fireplace. Whitish limestone that on only the third day of use turned orange right above the fireplace. So obviously heat is part of this equation. What is causing it? And how can I fix it? I sealed it per manufacturer instructions so unsure if the issue is the sealant, the stone, or the gas fireplace.

    • Donato Pompo says:

      Normally when limestone develops an orange/yellow stain it is due to being subjected to excess moisture. I would not expect moisture to get to a location right above the fireplace, but since it is a new installation moisture could migrate from the thinset mortar adhesive that contains water when it is first applied. It does cure and dry by moisture absorbing into the stone or the substrate; plus there is a chemical curing through hydration.

      If moisture isn’t the problem then maybe if you have a gas fireplace the fumes are reacting with the sealer? Assuming it is only a surface stain, then there are stone cleaners that are slightly acidic that are used for removing rust. I have seen these diluted acidic cleaners remove orange-like stains. It would be best to hire a professional stone restoration person how has experience in cleaning these conditions. Whatever you do, test it first to make sure you get acceptable results.

Leave a Reply

Your email address will not be published. Required fields are marked *