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Limestone Cure / Clean 

Areas: floors, benches, external walls, interior walls, building walls, countertop, bathrooms, kitchens, fireplaces, pool deck
Problems: dirty, darkening, stains, spots, scrathes, holes, wear&tear, chipping, powdering

Q 2336: We have a limestone floor that after a upper level flood, the water staining caused yellow/ brown stains. We think it may have been from the dye in the carpet that was upstairs. We applied a poultice to draw out the stains and it worked really well but now have a powdering problem. It seems that the stained areas are still drying out after over a month.
Is that all it is? They have shrunk by about 50% and we dust off the powder almost daily. Any more input would be grateful. Derek. July 29, Reply
R1: Dear Derek: It looks like you're doing all right on your own! Maybe, to speed up the
drying process, you my consider operating a de-humidifier in that room. but if you don't have one, don't bother buying one, It will dry by itself, eventually. Maurizio, USA, Expert Panelist
Q 2231: We have a bench in front of our brick fireplace made of light gray limestone that is cut and smooth, but not polished. Over the years, the place where people sit on the bench in their grubby jeans has turned the surface dark and greasy-looking. The ends of the bench are still light gray. I've tried the usual household dirt/grease cleaners, but they don't do a thing. Help, please.... Cheryl, July 15, Contact
R1: Dear Cheryl: Have your friends sit on the clean areas of the bench until they become dirty, too!!
Jokes aside, try a solution of hot water and household bleach (3:1), a natural fiber brush (tampico -- like the ones they used to do laundry), and a few gallons of elbow-grease!! Ciao and good luck, Maurizio, USA
Q 2210: I have just moved into a 130 year old house in Sheffield in the UK with limestone external walls. The walls are unsurprisingly very grimey after 130 years and I am interested in the most suitable solution for cleaning - is it best to sandblast, waterblast or chemical clean? Whichever method is the most suitable, what products (chemicals, biocides etc?) should I be using? 
I am thinking of doing it myself (fairly good at DIY) and am keen not to use a method which would require extensive repointing - the pointing is actually fairly good as the house was repointed a few years back (but the stone wasn't cleaned). 
Could someone also advise what should be applied as a protective coat once the cleaning has taken place? Many Thanks, ben, July 12, Reply
R2: Dear ben: Firstly I would really think twice about using an abrasive method of cleaning such as sand blasting or using chemicals short term they may have a pleasing aesthetic result. Long term you may impair the stone face aesthetically and structurally. 
You can send me a picture and I will try to help you. I am familiar with conditions in industrialized cities such as Sheffield. 
Any restoration should start with preparation so first make sure that no organic material is in touch with the stone to avoid any dissimilar reactions in future This includes anything that may be climbing the stone fašade such as creepers or Ivy Make sure flower bed earth and any other material is not in contact with the fašade above the DPC level. It is also important to note that a healthy fašade is one that sheds moisture not retains it. It may be worth your while testing various parts of the fašade with a damp probe (you can rent them or if you have a friend who is a building surveyor you might be able to borrow one). Ensuring adequate ventilation is a must you actions in cleaning the fašade with high pressure water may cause more damage than you think. 
It is quite common in your climate that buildings are damp. When you clean your fašade you may find that the colouration of the limestone varies significantly. Where moisture content varies and in trying to achieve a homogenous finish during cleaning you could damage the surface of the stone. be very careful around rain water goods as you may well uncover stains where iron fixings have been used and the current patination is covering this. 
The most appropriate method of cleaning will be using a high pressure hose system with an action nozzle such as a pulse effect. 
Select a neutral area were you can test the effects of your labours. Try spraying in circles and don't try to have too much effect in one go (You can always let it dry and give a second treatment later). Try to vary distances, action and angle to achieve the best finish. Note the time and application to try to devise a way of achieving the most appropriate homogenous finish. If surface treatment is evident, such as sealants or anti graffiti paints or other because chemical treatment, cease treatment immediately and consult an expert as often when surface treatments have been applied to limestone delamination of a surface layer occurs during the cleaning action. Delamination occurs because surface treatments lock in moisture beneath the application changing the physical make up of the stone. Natural patination can also cause the same effect especially in heavily industrialised atmospheres and where the stone has been well exposed (such as West facades against the prevailing winds). Always try to avoid over saturating the stone especially where the fašade is shaded or where surface salts may be present. If salt emission is high (if salt debris collects on the surface), then you should correct this before you consider cleaning as you may well provide the catalyst for future structural damage.
In a project like this, you should always ensure your fašade is working before attempting the cosmetic stuff, Steve, Poland. 
R1: Dear ben: Personally I'm very much against sand-blasting. If it were up to me, I'd ban 
it alltogether!
If I were you, I'd try to power wash it with a solution of hot water and bleach (4:1) keeping the pressure at no more than 900 PSI. Keep me posted. Ciao and good luck, Maurizio, USA
A 2152: I want to seal recently installed natural limestone blocks that are the exterior of my home. Wind driven rain managed to soak through onto one floor area I am in Lampasas, TX. Thank-you! Al, July 2, Reply
R1: Al: I have been putting limestone veneers on homes in Central Texas for 30 years now, and have never seen or heard of driving rain penetrating the stone. Also, to the best of my knowledge, none of these stone veneers where ever sealed. I am assuming that you have a standard 5 inch veneer wall What type of limestone is it? (chopped, flagging?) Most often, the water penetration you describe is due to faulty sealing around windows or doors, or it could be due to improperly installed flashing. 
I am not far from Lampasas, and would be glad to take a look at your problem (at no charge), and point you in the right direction. Good luck, JVC, USA
A 2122: We have a problem with staining from soap and toothpaste spatter on a Pietra Serena (light grey) limestone slab countertop in a master bathroom. The stone has a honed finish. We've tried the sealant that was recommended to us through the stone fabricator, but it still stains. The limestone is so porous, that it is so susceptible to stains, and the homogenous nature and color of stone makes the stains more pronounced. What can you recommend? Thanks. Jeni, June 26. Reply
R1: Dear Jeni: Your "stains" ain't stains. They are acid etches instead; therefore, you can keep sealing your top with an impregnator/sealer until you drop, but you will never be able to prevent them. Now, to repair your surface damage (that's what acid etching is) you need a professional stone refinisher. Maurizio, USA
A 2094: I have an apartment complex with a large French limestone lobby. It was put down about 6 years ago and is showing a lot of dirt and wear. I have a very capable maintenance staff but I need the product. Can you tell me where to get a cleaner. Please do not recommend a outside company as my owners will not approve it. Help! Charlotte, June 20, Reply 
R1: Dear Charlotte: Well, now that we know that your boss wouldn't approve an independent contractor that know what they're doing, and insists at solving the problem "in house" with some "special" cleaner, the only thing I can tell you is my salutation  trademark, that is ... Ciao and good luck, Maurizio, USA 
A 2086: I would be interested in a shower spray cleaner. Our limestone shower (sealed) was put in two years ago and we have a soap scum build up. I have cleaned it regularly with vinegar and water but it really hasn't taken care of the problem. I would appreciate a name of a stone cleaner for this purpose. Diane, June 19, Reply
R1: Dear Diane: They didn't give you much information about maintenance of natural stone where you originally bought it, did they! What a shocking surprise! Water and vinegar, uh ... That's a good one, all right, especially for calcite-based stones!! Maurizio, USA, Expert Panelist 
A 2076: I stupidly installed limestone in my kitchen and after a few weeks have shadows, and one area of white spots where lemon juice was spilled. The counters have been sealed already, should I however have it re-honed and re-sealed? Perhaps the original sealant was not of the best quality?,Vicki, June 17, Reply
R1: Dear Vicki: When you said "stupidly" you said it all. In fact, if there were a remedy to your situation, it wouldn't be "stupidly", would it!! :-)
The sealer has absolutely nothing to do with the etching (not staining) that you have when you spill something acidic on the surface of your top. Etching is not related to the porosity of the stone (which is what an impregnator/sealer deal with), but exclusively to the chemical makeup of the stone (Calcium Carbonate). No sealer under the sun can protect your stone from acid etching.  A good piece of advice: Get rid of it and get over with your nightmare. You made a mistake, don't stick to it. It's only money and, I believe, your mental health is more important than money, isn't it!
Sorry., Maurizio, USA
A 2040: We recently had a beautiful fireplace installed with a large light gray limestone mantle and header. A workman knocked over scaffolding and put a 1 inch chip in the top edge of the mantle. The masons have tried to patch the chip, but the color is too light (white) and the patch doesn't have a crisp edge. Is there anything that can be done to repair it so the damage isn't so noticeable. The fireplace is the focal point of the room and the chip is very obvious. Duwes, June 10. Reply
R1: Dear Dewes. What an unfortunate accident. Patching of chips and other surface damage is an acceptable practice, and there are companies that have spent a lot of time and research in developing patching material to match different limestone. Obviously, whoever tried to put the patch on your fireplace mantle did not have very much experience. See if there is a stone restoration company in your area that can handle the job, and make sure the contractor responsible for the initial damage is going to pay. Now for the disclaimer. Patch is not stone, and it will always have a different appearance, no mater how skillfully applied. This becomes particularly obvious when a sealer is applied, or the stone gets wet. Maybe having the contractor replace the stone is the best fix for your problem Good luck, JVC, USA
A 2035: Help! Our kitchen floor is a disaster area. We have laid 32sq m limestone "Florence" from Mandarin. Prior to sealing it with 'lithofin' stain stop we were trying to ensure the beautiful stone was perfectly clean from grout etc. We used Wickes' patio cleaner (less than 10% hydrochloric acid aaarghh) mixed with water 20/80 thinking this would be a weak enough solution to do no damage. Unfortunately we were wrong. We have a nude stone floor with sweep marks and splashes which seem to be permanent and do not know which way to proceed. Any ideas? Any magicians? Yes we were stupid, but the heartbreak is punishment enough. Thanks for reading - depressed yet still hopeful of Chester. UK. June 9. Reply
R1: Dear Chester: And we don't want no broken hearts, do we!! It's not hopeless, but there's only one answer for you: Get a professional stone refinisher. They will be able to re-hone your floor to a finish very close to the original, thus eliminating the surface damage made by the acid. It will cost you a pretty penny, but it's only money and your heart will be mended! ,Maurizio, USA
A 1989: I just read the attached answer
R2: I am very much against sandblasting. I declined good job opportunities (to restore monuments or such), because the specs prepared by the bureaucrats required sandblasting. If you're not convinced enough, just take a look at the mess they did with Capitol Hill! The safest way to clean limestone is to power-wash (with a pressure not any higher than 900 PSI) the stone with plain water. This sound concept is pretty old, and is due to the fact that back then there were not many specialty chemicals available. Nowadays, however, there are some good cleaning products that can be safely used to power-wash (still at a low pressure) stone surfaces. The fact is that they do clean better than just plain water. I hope I was not too late. Good luck, Maurizio, USA, 
Maurizio: In your opinion is cleaning slightly sandblasted limestone in pool deck with a power-wash (pressure of no higher than 900 PSI) still the best way to clean the limestone. Thanks, Aida, MEXICO, May 31. Reply
R1: Dear Aida: Yes, it is Ciao and good luck, Maurizio, USA
A 1721: We had tumbled Jura gray limestone installed in a steam shower. After 10 days of use, rust spots are appearing on the stone surface, not confined to any particular area of the shower. They are not showing up near the shower head. Can you tell me why this is happening, and what measures can be taken to stop this if any? Jurri, April 17. Reply
R1: You can try a commercial rust remover. Without seeing the installation or knowing how it was installed I can't direct you. You probably want to prepare yourself for an eventual removal of the material. Regards, Steven, USA
A 1654: What product can be used to clean the surface of a variegated beige limestone countertop that had a penetrating sealer. This is new in a new bath/master suite area, the space still unused. Various items were stacked on the countertop during 'moving in', mostly books. A dull appearing dotted bluish residue is in scattered areas. Rubbing with a micro fabric cloth removes almost none. Advice? Garner. April 5. Reply
R1: Dear Garner: I have no idea as what your problem is. Staining? ... From books? ... I really don't know. What I do know is that -- like I have had the opportunity to emphatically state countless times -- I would not consider limestone in my own house if they'd pay me to get it! Way too many problems of uncertain diagnosis and, most of the times, with no solution. 
but I guess it's too late now!... Ciao and good luck, Maurizio, USA
A 1393: I just got a problem of scratch and spot hole (about 5x5x5 mm w/h/d) with my limestone floor on few places due some tools dropped, and black stains some areas due wet surface. Is there any product / glue can repair those scratch and spot holes? And how to clean the black stain? Thank you. Prasong, Jan 31. Reply
R1: The only way to repair the scratch is to sand it off. For the holes, if it's deep enough, you can fill it with epoxy glue to match the color. About the black stain, I have no idea how it was formed & therefore, without that information, I wouldn't know how to remove it., Maurizio, USA
A 1360: We had a limestone floor installed 2 weeks ago. The installer put the thinset on in the middle and around the edges of the tile. The tile has remained dark where the thinset was and where he did not put the thinset there is a lighter ring. It's on all the tiles. because the stone is dark gray, the installer used a dark thinset. We've since been told by others that this was a mistake, that white thinset should be used with limestone. Short of redoing the floor, do you have any solutions? Mira & Tim, Jan 22, Reply 
R2: I don't know if the the thinset is completely dry. How much time has elapsed since the limestone was installed? If it is less than a few weeks, you may take the do nothing approach for a few more weeks. Maybe it will continue to dry. I fortunately, have not had much to with remedy this type of problem. Regards, Steven, USA
R1: Dear Mira & Tim: Nope. Ciao and good luck, Maurizio, USA

A 1278: After only a few months, our new limestone countertops are reminding us of every dinner party we've had since they've been installed. The "water marks" from wine glasses or Coke cans aren't so bad. but lately, we've noticed some "white scars" from spilled food. How can we refinish the surface to restore a consistency to the counter tops? Dick, USA, Dec 23. Reply
R1: Dear Dick: This goes to prove once more (as if it were necessary!) that calcite-based stones don't belong in a kitchen. It can be fixed, but it's not -- by far -- a DIY project. Hire a good stone refinisher and have him produce a totally flat finish (low-hone). It will help minimize the visual effects of etching. Have it sealed, too. At least it won't stain. I forgot the best piece of advice possible: GET RID OF IT AND LIVE HAPPILY EVER AFTER! Ciao and good luck, Maurizio USA

A 1165: I would be very grateful for any advice you can give me on cleaning bathrooms with stone (polished limestone and tumbled marble) floors. How do I clean the rest of the bathroom without damaging the stone? This problem is driving me crazy. The cleaning and disinfectant products typically recommended for the rest of the bathroom (walls and fixtures of glass, mirror, acrylic, porcelain, ceramic, and nicked) are either acidic or harshly alkaline, therefore potentially very damaging to the stone. There are patches on the polished limestone dulled by something or other (drops of toilet cleaner perhaps? Uric acid? Ammonia?). Can you suggest a repair which will restore the luster of the floor - as well as a simple (I am REALLY into SIMPLE) cleaning solution which is safe to use on everything? I never dreamt that cleaning a bathroom could be so complicated!!! Thanks !!! Ann, Nov 5, Reply
R1: To answer your question, we suggest you contact a stone restoration company in your area. A restoration mechanic can do the necessary repairs and perhaps seal the floor. The regular cleaning of the stone after the process should be very simple. Sincerely, Alicia, USA
R2: Dear Ann: I pledged with myself not to use this wonderful site to free advertise my products, although, to the best of my knowledge, my company is the only one that makes specific products for marble bathrooms (showerstalls). I feel it would be distasteful, as well as unethical. Therefore, unless you get in touch directly with me, I will answer your question in generic terms, such as, "You do need specialty cleaning products", which is something that you already knew. I want to take the opportunity of this subject to make a comment. Your inquiry begs a big question: "Why is it that you're coming to this site with your questions. Nobody here is making any money by answering questions like yours (I don't mean to be rude, just to drive home a point). How about the dealer who sold the stone to you, and the setter who installed in your home? They made good money out of the deal. Shouldn't they be the ones who ought to make sure that you're going to enjoy what they sold to you for years to come, by supplying you with some basic intelligence and proper products?" It makes sense, doesn't it. Well, probably that's exactly what's wrong with it! Ciao and get in touch with me, Maurizio, USA
R3: Hello Ann, I hear your frustration. I believe that simplicity can be achieved by recognizing that all the products can be "cleaned" with one cleaner. The nickel may be the exception but maybe not. It requires a neutral cleaner that can be left on without taking it off. There are neutral marble cleaners available in the market and I have recommended them many customers. I am aware of an excellent product. The man who helped formulate these products will not endorse them so I will. About the dull areas you will need to call a professional in to repolish them again. best of luck, Steven, USA

A 1174: Our building has been standing for about 30 years and the lobby wall & on each floor are covered up to half the height by polished limestone slabs. We are having the building renovated (very slowly!) & would like to know how to clean & restore the stone. (Here it is the basic lining material for walls) The stone is quite dirty & stained & of course quite dull after such a long time. Also small areas are slightly eaten away due to the fact that water leaked out from an apartment to the outer wall & of course one can see the white salts that have been pushed out on to the stone surface. Thanking you, Mervyn. USA, Nov 10. Reply 
R3: Mervyn, The process is two-fold. 1) You want to have the limestone cleaned sufficiently to reveal any damage. 2) You probably need the limestone restored in areas that have suffered the most damage.
For both of these tasks you need a professional marble restoration company with people with proven track records. best regards, Steven,
R2: This is a job that you should probably have a professional stone restoration person look at. Yes, there are ways to renew the stone, but the process will depend on the nature of the staining, the texture and density of the stone, etc etc. Surface dirt, and the accumulated patina of time may be removable by a light sanding... Random orbital sander or palm sander with a 60 grit or finer paper. Some penetrating stains may be lifted out using the appropriate poultice (described elsewhere on this site). Since most limestones do not, by their very nature, polish (although some of them do) after cleaning, there are special waxes, and/or sealers that would be appropriate. However, there are so many variables here, that you would be wise to seek out a professional in your area, and have the job actually looked at. Good luck, JVC, USA
R1: Hi, Grind, Hone, Polish & Seal. You need a professional to do it. Pini, USA
Thank you all for your information...I will bring your answers to the Apartments Committee & see what they have to say!! Gratefully, Mervyn
A 1076: Care: Please can you offer advice for specifying the correct sealant to use on honed 'Panna' Limestone floor tiles in bathroom areas? It is very urgent. Please could you respond as soon as possible, thank-you! Alexzander, August 25, USA. Reply
R1: If I were able to specify the "right" sealer for each and every stone available on the marketplace (and counting!), somebody would go as far as calling me GOD! Not one single sealer is universally good on any stone, including my own. In the case of this "Panna" limestone (by the way, "Panna" is Italian for cream), I have not the slightest clue. Never heard of it before. Maybe I know that stone very well, but certainly not under that name. The sealer that we make, is an impregnator for stone, it is a very good product (to the best of my knowledge is the only one that comes with a 20-year warranty), and covers a vast range of stones. All types of limestone we've tested it on so far were pretty much sealed.  All I can say to you is
that it represents a good bet. Good luck, Maurizio, USA

A 996: We live in the only hand cut limestone house in Oak Park IL. Lots of churches with the same stone but no residential homes. The house had old large shutters that have been taken off because we are having it tuck-pointed. Now we have dark dirty stones where the shutter hung. Should we sandblast or have a chemical limestone cleaner applied to the house?  Contractors that do the cleaning say never sandblast the limestone as it will pit and make it more prone to absorbing dirt. Some contractors are telling me that the chemical cleaners may not get the carbon monoxide out of some of the stone. I am most concerned about whether or not sandblasting will alter the stone or if chemical washing is the way to go. USA. May 24 reply

R2: I am very much against sandblasting. I declined good job opportunities (to restore monuments or such), because the specs prepared by the bureaucrats required sandblasting. If you're not convinced enough, just take a look at the mess they did with Capitol Hill! The safest way is to power-wash (with a pressure not any higher than 900 PSI) the stone with plain water. This sound concept is pretty old, and is due to the fact that back then there were not many specialty chemicals available. Nowadays, however, there are some good cleaning products that can be safely used to power-wash (still at a low pressure) stone surfaces. The fact is that they do clean better than just plain water. Good luck, Maurizio, USA

R1: Definitely don't sandblast !  You will definitely clean the stone, but surface damage is likely to be  extensive and lead to increased deterioration.  The stone should be treated with a biocide to kill any organic growth and then cleaned by hot water low pressure cleaning. An alkaline or neutral detergent can be used to assist removal of grime.  Make sure you use a contractor who has experience in heritage work - not someone who usually cleans brick walls or removes graffiti.  If biological growths on the stone are a problem, get the contractor to spray biocide on the stone after cleaning as well. Regards, Jim, Australia 

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