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General Cure / Clean 
Issue: sandblasting, staining, grout, color enhancing, etc.

Q 2348: My wife and I just purchased a condo on the Gulf of Mexico. A lot of the unit is tiled with travertine. Many of the tiles sound hollow when tapped with something hard, and some tiles actually creak when they are walked upon. Is there a solution short of tearing up the tile and replacing it? ben, July 30
R1: Dear ben: Nope. Maurizio, USA
Q 2309: I would need to sandblast the exterior of the building which is made of stone with mortar infill and the oak beams inside which are painted lightly with emulsion and pitted with old (and possibly new) woodworm exit holes and powder debris in places. basically the beams are sound however and once the top surface is cleaned off from its emulsion cover and the woodworm holes I will treat them with a proprietary liquid commonly available in France.
The question really is based on the cost that the French master builder is charging to do this job which, may or may not be fair as I cannot assess it out of ignorance. If I could find - someone in the trade who could advise on cost it would be helpful. Thanks, Leo, July 26
R1: Dear Leo: I really have no idea of what one should be charged for a sand-blasting job 
in France. What I do know is that -- if it were up to me -- I would put in jail, without even the benefit of a trial, all the sand-blasters of the world. And I would throw away the keys, too!! There are much better ways to clean exterior stone surfaces without badly damaging them (all too many times for good). Maurizio, USA
Q 2285: My daughter colored her hair and got stains on my sink. What can I use to get the stain out? barbara, July 23
R1: Dear barbara: You want to try a poultice with talc (baby powder) and Hydrogen Peroxide (Salon grade, 30 / 40 volume), Maurizio, USA
Q 2276: I have a stone table in the dining room, but it is so porous that it is getting stained. What do your recommend we seal it with so it acts more like tile when we use and wash it? Thanks, Keith, July 22
R1: Dear Keith: Tell me what stone it is and, most importantly, describe how the stains look 
like to me. Only then will I be able to tell you what to do. Maurizio, USA
Q 2258: Hi! I recently purchased a table from a school science laboratory, and I'm told that the table top is slate. Since I am very unfamiliar with this material, I have many questions. First of all, how can I tell if the top is really slate? And, if so, how can I tell if it's a natural slate or some type of compound? My main concern at this point is that it has some type of black rubberized protective coating which appears to have been painted onto it, and I'd like to remove the coating without damaging the "slate" underneath. I have scraped off some of the coating in order to examine the stone beneath it. It is a smooth black/charcoal gray stone with a rather dull finish. The coloring is consistent with little or no color variation. Any ideas on what this stone material is and how to remove the protective coating? Thanks for any advice you can offer! Laura, July 19
R2: based upon your description, your stone is probably a slate chem-lab table. Use a paint stripper containing methyl-chloride to remove the coating. Observe manufacture's warnings and rinse thoroughly. After the stone dries, apply one or two coats of penetrating sealer. 
Mike, USA.
R1: Dear Laura (if you'd pronounce your name LOW-RAH, you'd be my wife!!):
I don't think that anybody can teach you over this site how to recognize if a stone is slate or something else (I would exclude the possibility of a manmade compound). Typically, however, many a school science lab table were made out of soapstone. The way you describe the stone part of the where you have removed the coating, seems to confirm that. but, of course, it's just a (n educated) guess.
To remove the coating you will need to use a paint stripper based on Methylene Chloride. No solvent would ever damage stone. besides, the reason why soapstone was so popular as science lad table top is due to the fact that it's quite impervious to harsh chemicals. Maurizio, USA
Q 2239: Last year we installed a flagstone walkway which was set in a sand base. Recently we noticed dark stains appearing on several random stones. We cannot identify the stain nor the reason why this is happening? Thank you, Roseanne, July 15.
R1: Roseanne: You do not identify the type of stone ( flag stone describes a specific form, but not type) but aside from that, it is the nature of all stones to begin to darken and eventually turn gray/black because of a phenomenon called weathering, especially when directly exposed to the elements. The staining you are seeing is probably the beginning of this process, and is probably occurring where it is because these particular areas 
1) stay a little wetter than the rest of the walk way, or 2) there is overhanging vegetation, or 3) your dog has taken a shine to these particular stones, or 4) a mineral streak in the stone that is oxidizing, or 5) a combination of the above. If you find it impossible to live with what is essentially Momma Nature's way of putting a protective coat on the stone, then you are going to have to do it for her. First, try some bleach on the stains and see if it removes it. If it does, great! Then apply a sealer,, so that the little mildews and alga that cause this to happen have a harder time getting a toe hold on the stone. Then repeat this process oh once a year or so. Or sit back, let nature take its course, and enjoy walking your flagstone walk as it gently ages and settles into its new environment. JVC, USA
Q 2191: I just closed on my house about 3 months ago. I am very concerned for my stone (limestone, granite and slate). I was advised that sealed granite kitchen countertop (Atlantic black Granite honed) can be cleaned with soap and water or a glass cleaner without ammonia. My kitchen floor is unsealed Slate (M-1 Ebony Slate). 
In my bathroom, I have honed Gasgogne blue (which only today have I figured out to be a limestone and not a marble) it's very lovely but we're having problems with the tile in the shower area. About 2 months ago, we decided that we wanted to seal the bathroom tile. We've been trying to seal it and have waited 8 weeks for it to dry. It feels dry when touched but has about 8"-12" on all walls with stains which look like water stain. This mark goes all the way around the shower. We don't think that there is a leak because it should have showed up in the floor below by now. What do you think is the cause and remedy? Any clues? Anyway, if you could kindly sell me some products and tell me what to do with it, I would be very grateful. 
I know that you get annoyed with consumers like me who have to turn to an expert for help, but we are at the mercy of the seller/marble retailer. I bought my house from a developer and their subcontractor seems quite clueless. Where I can buy the products? Thanks. Michelle, Chicago. July 9
R1: Dear Michelle: One thing at a time. Atlantic black hone-finished "granite" (actually an Anorthosite, not ) can NOT be sealed with an impregnator type sealer. It 
would represent a maintenance nightmare, because all sorts of surface soiling will show and you'll become a slave of your tops! To minimize the problem, if the stone has been sealed already (along with the brains of the contractor who did it!) the sealer MUST be stripped with a Methylene Chloride-based paint stripper (anything else won't cut it). After that, a good-quality color enhancer should be applied to minimize the problem (if there's a sealer, the color enhancer won't have any chance to be properly absorbed by the stone the way it should to work). With that your countertop will turn permanently black -- though still dull, and will show less surface soiling. The cleaners the geniuses who sealed your countertops suggested you to use are quite wrong (what a surprise!!). Do NOT use either one of them. There are several postings on this particular subject on this very site.
As far as your kitchen floor is concerned, I have only one comment: I feel deeply sorry for you! You will find out why sooner than you may be afraid of. 
Unfortunately there's very little remedy. That stone does not belong on a floor to begin with, let alone a kitchen.
Finally your bathroom limestone. How do you want it, sugar coated or right in between your eyes? I'll make the decision for you:
Time and again I strongly advised people against using limestone in their homes. Most of the times there are no problems, but the few times that problems arise -- like in your case -- they're always terminal (with no discernible solution, that is). In your case, for instance, the problem you're reporting could be caused by a variety of factors, i.e.: 1) an unexpected chemical reaction between the setting material used to set the tiles and the stone makeup (nothing you can do about it). 2) Poor installation technique (the tiles have been butt-jointed, perhaps) and there's grout or caulk missing. And so on. Sorry about that. (Oh, by the way, that was the sugar-coated version!)
Finally, I never get annoyed by requests like yours. I do get annoyed at realizing -- day in and day out -- the hopeless specific ignorance displayed by the vast majority of stone operators.
See my 'Do's & Dont's' Unfortunately they won't do you much good at this point., Maurizio, USA
A 2156: Please tell me if I can re-apply new grout to good existing grout where too much was removed during the sponging off process. This grout is in good condition & has cured for several months. The grout has not been sealed yet. We were hoping not to have to remove the existing grout. Roxanne, July 3
R1: Dear Roxanne: You can try in a small area. It usually won't work though.Maurizio, USA.
A 1626: I have just purchased a new house (built 18 months ago) and have a stone tile floor in a bathroom.  A few of the tiles were cracked and the flooring subcontractor who built the house removed 10 tiles from the floor only to find that he couldn't get a good color match. The sample of the tile states that the name is "Silver Travertine" (with a supplier stock number of 1205). The original tile vendor still stocks the product; however, the currently available stock is significantly more brown than the original and would look terrible. How to get a dozen or so Silver Travertine tiles that might be a better color match. Matt in Dallas, TX. March 31,
R1: It is impossible for anyone to match a natural material without physical samples. I would suggest you or your installer remove the installation and start over to achieve a match. The other course of action is to put a sample back in the hands of the distributor and hope that they can find someone else who received the material at the same time. Regards, Steven, USA,
A 1504: I am in the process of buying a new house. Unfortunately, I am not able to pick the color of the marble surrounding the fireplace - I can only get white marble, which I don't particularly like. Is there any way for me to change the appearance of the marble once I move in? Can it be stained or painted, etc? I don't have the money to totally replace it. Any suggestions would be greatly appreciated. Thanks! March 8.
R1: Dear March 8: Are you kidding?! Ciao, March 16, USA 
A 1471: I have a river rock fireplace that needs an exterior sealant. I am looking for the appropriate product and haven't hand any luck. I wish to apply something that will bring out the color of the rock (as we see when they are wet) but yet do not want a high gloss look (preferable would be a satin sheen). I have tried a saltillo tile sealant on some of the rocks/ it produces a satin sheen but doesn't really retain the vivid color of the wet rock. Help! Scot, USA. Feb 24.
R1: Try removing the topical sealers that you have applied. Then use a color enhancer. Once it looks the way you want it to then seal it. regards, Steven, USA
A 1344: I have a Green stone counter top that was just installed. before I could seal it my dog got on the counter and urinated on it. Can you tell me what kind of poultice to use to extract the stain. Thank you, Robert, Jan 17.
R2: Dear Robert: It's shouldn't be much of a problem. Poultice with CLEAR Hydrogen Peroxide 30/40 volume, available at a beauty salon near you. I like baby powder as the absorbent agent. Maurizio, USA
R1: What kind of green stone is it? Generally, clean with 12% hydrogen peroxide and a few drops of ammonia. Test a scrap piece for color fastness before proceeding. Regards Steven, USA
A 1416: I found that a paper towel soaked in Acetone (Nail Polish Remover) does the job way better than poultice. again, put the paper towel over the stain, cover the whole thing with cling wrap and tape the sides with tape. Wait until the paper towel becomes dry 12-24 hours - and the stain should vanish.  However, now the sealants have also been taken out. You should use any granite silicone based sealant to seal this area. Sridhar. Feb 7.
R1: For starters, paper towel soaked with acetone (forget the nail polish removers: In the past few years they've been heavily reformulated) IS a poultice. 
Second, acetone only removes oily stains, period. For organic stains you need something else, and yet something else for biological stains, and again something else for metal stains, etc. 
Finally, a poultice with acetone only take a couple of hours, tops (after you remove the plastic cover) to dry completely. Ciao, Maurizio, USA
A 1307: I have a client Whose main concern above all is their grout to get cleaned. The stone needs a hone and a polish as well. I think this will do a good job as far as getting the grout cleaned. They told me last time When, the floor was serviced with the same request, the company ended up removing lots of the grout and putting new in. How would you approach the job. Its a upscale clothing store and the stone they want the work done in is the public restrooms. I haven't see the floor yet but this is the information that I have. What are your thoughts? Randy, Jan 8.
R5: Randy, The newest and most innovative method of cleaning grout lines is the Vapor Steam cleaning system. You may use nothing but the hot penetrating power of the Vapor Cleaning System or you can use a grout cleaning chemical in conjunction for real difficult stains and jobs. Good luck Jerry, USA
R4: You do not need to remove the grout, All what you need is a grout grout cleaning product. I, personally as a stone restorer, for the past 18 yrs, use an intensive grout cleaner with a soft brush, It does a very good cleaning job. You may try it to see the result. Freddy, USA
R3: I refinish at least 100 marble floors a year (honing & polishing). Since I actually polish the stone surface (I use a polishing powder -- my own ), many a times most of the grout gets cleaned, too. It much depends by the type of grout, how recessed it is over the surface of the tiles, etc. My formal contract, however, specifically excludes -- in bold letters and non uncertain terms -- the cleaning of the grout as part of the job. I am stone refinisher, not a cleaning contractor. I used to offer such service on the side, but then I just pulled out of that business altogether. Too many aggravations and risks, too: several times part of the grout was coming loose and they expected me to rectify the situation for free. Some other times, no matter what I was doing to it, the soil was so deeply inbedded in it that it would never come clean, or, maybe, it would not come as clean as the areas near the walls, etc.. Conclusion: since there's no such a thing like a sure formula on how to go about cleaning grout, the gamble was such that they could not pay me enough In my neck of the woods, there's a company specializing in cleaning grout, and I believe is some sort of a franchise thing. Man, I've seen some of their works and I can tell you that they are darn good! When some customer insists on the cleaning of the grout, I refer them to this company and everybody's happy. I seldom do commercial work (I make it my business to be the highest bidder all the time!), but if I would ever face a situation like the one you're describing, I would hire them as a subcontractor (and even make a little money in the process!). That's what they do. That's all they do. Maurizio, USA
R2: Dear Randy: This is a very common problem. I am not aware how the stones have been laid and what is the grout width. If they are laid "bUTT" that is with minimum grout spacing then hardly any grout would show. but from the problem, it appears they have left a certain gap say 3 -5 mm or more for grout. Honing does clean up the area but if the joints have been chamfered and are in a groove form then it is difficult to clean it by honing. We had recently carried out a similar job wherein the grout width was 4 mm and the stone were a mere 50 mm x 50 mm hand tumbled. the area was LARGE. 60,000 sq. feet in all. We did acid cleaning of the grout taking care to use very dilute HCL (hydrochloric acid) and then using a detergent to clean up the grout. This attempt was not very successful as the stones were being affected by the acid. We then used high pressure water jetting along with high pressure stem cleaner to clean up and this did the trick. The dirt actually came out without damaging the grout. Later we sealed the grout with a penetrating sealer and then topped it with a water repellent silicone layer (just the grouts). It has been six months now and the area still looks as good as new. I hope this information comes in handy. We also stock and sell special grout cleaning formulations. Arun, India
R1: Hi, visit www.findstone.com/articles.htm. Pini, USA
A 1303: Attached are pictures of a shower enclosure I installed in the summer of 2000. I did not install the tile floor but did supply the tile. The installer seemed to know what he was doing and did some beautiful work around the house. He set the tile in an epoxy based thin set over a rubberized membrane, after I had installed the walls with Liquid Nails 602 over cement board. Several weeks later, still during construction, the staining in the floor showed up. Working on the belief it could be moisture, we let it be. Last January, while the owner was out of the house for 2 weeks, we put a commercially prepared poultice for oil on some of the stain. We covered the poultice for 2 days then removed the plastic and allowed the poultice to dry. Where we had put the poultice the stain moved into the walls as you see it in these pictures. The customer has been very understanding about the fact that the original stain was due to nothing we did, however he is upset about the stain moving up the walls (no more than 2 inches). Do you have any ideas as to the cause of this stain or how I can test it to find a proper stain removal tool? Any Advice will be appreciated Thanks, and Happy New Year George, USA, Jan 5
R3: The photos show that all the tiles around the edge are "stained" and the staining boundary appears to follow the edges of the tiles, i.e. the stain does not creep over to cover half a tile. because of these points, I suspect firstly that the stain is caused from below and the staining pattern is related to the laying method. Are the unstained tiles drummy? Are the stained tiles comparatively damp (check with moisture meter). The stain rising up the wall suggests an active staining agent or if it is just water, an active leak. I think your next step is to check if the floor is damp to determine if you are dealing with some form of leak to positively eliminate this possibility. It would be very helpful to know if the stain varies in intensity at all and if the colour variation is noticeable when the floor is wet on the surface. Regards Jim, Australia
R2: Dear George: Now that I had the opportunity to observe the pictures, I am more than positive about my diagnosis, which is that you have a lot of water under those tiles. Two other considerations come now into the surface: 1. The selection of that particular stone, which looks like Kashmire (granite? Yeah, right! And I am the emperor of China, too!) for a shower stall is disgraceful, to say the least. Unless those tiles were sealed only the Gods know with how many massive doses of impregnator, that stone is so absorbent that it WILL allow water going all the way through it. 2. the floor has been installed after the walls. This translates in a very weak "Achille Tendon" in the overall picture. In fact, even the minimum failure of the caulk, or grout that was applied where walls and floor meet, will lead to an immediate access of the water under the floor tiles, with the consequence that you can clearly see. The whole thing is screwed-up, George, and you can listen to all sorts of advice, but you will eventually have to conclude yourself that there's no other remedy if not ripping out at least the floor, let the shower enclosure dry completely until the staining in the lower part of the walls disappears (hopefully!), try to seal at best the new tiles before you install them (I would go as far as using penetrating epoxy in the back to try to seal them, let the epoxy cure for several days, then literally soak the tiles with a good quality impregnator), caulk as thoroughly as possible, and keep your fingers crossed. by the way, looking at the pictures it appears to me that the tile setter did a good job. I can detect a proper gap in between tiles for grouting. Further, you're reporting he had used epoxy setting. Nothing wrong there! Maurizio, USA
R1: It looks like you have two problems here. 1st the product called Sahara beige/Ghibli is a very absorptive stone. So the stone has absorbed the moisture and possibly what ever else that is behind it that could bleed. Quite probably it absorbed some of the poultice. Second, Maurizio told you that the deposit at the joints is efflorescence. I advise removing the the stone and reinstall waterproofing because the efflorescence seems to be coming up rather than looking like a hard water deposit. This stone is really not appropriate for a shower and you must institute a good impregnating maintenance program for the consumer to follow and you to supervise. You may have a problem with liquid nail bleeding through. There are many reports that it can happen. I tell you because you sold them a stone that was unsuitable for a shower and installed the cement board with liquid nail. I am curious about the pan though, I wonder if your installer used a full spread method of installing the pan tiles. If he did I question whether or not he used epoxy. This is your problem whether it was by ignorance or negligence. I am happy that you cared enough to go this far. best regards, Steven, USA
Steven, I've used Liquid Nails 602 on numerous installations never had a problem with it bleeding through the stone. George.
R1: Hi George, I know. We did too for a few years. The manufacturers of liquid nail started excluding their products from areas with natural stone because many of them are too absorptive. Liquid nail in a direct wet area is something I have never done because we never found it to work. So what I will publicly say is this; the liquid nail should not have been my focus at all. I am sorry about it being construed as if it were. The most salient issue is the Ghibli and it being in a wet area. The staining problem you see is because of the sheer absorptive nature of the product. The probable efflorescence is why I mentioned liquid nail. If this is efflorescence, then water is getting to the core of the installation. This means that possible cementious nature of the backerboard is leeching. If this is the case then you have to stop water from getting into the substrate. How do you do this? Ghibli is tough to seal for a countertop and I consider it improbable to be able to stay ahead of the curve in a shower. Improbable because I have never taken the chance. If the installation was done with full spread epoxy adhesive, then efflorescence should not be occurring. That is why I question the adhesive. As an advisor on this forum, I only try and help all parties affected. I still appreciate the fact you are working on this. It speaks well for you. Regards Steven, USA
A 1279: Have water stains around the faucets in my bathroom. Seems to be slightly chalky. How to remove and seal? Cecil, USA, Dec 23.
R1: Dear Cecil: Try with a brand new razor blade. If the mineral has already dug into the stone surface, however, (pitting) there's nothing you can do, short of hiring a professional stone refinisher. No sealer will ever help you for that particular problem. Maurizio, USA

A 1230: I have a natural stone hearth and wall section for a wood stove. The stone is as if split in two with the split surface facing the room. This stone is from the Adirondack Mountains area & contains a lot of garnet. The stone is clean but shows no depth to the beautiful colors. Can you suggest a specific product to give me the color depth? Jack, Nov 30
R3: You will need to contact a marble or stone restoration person. Atkin, USA,
R2: Make the stone wet. If you like this look, then you can use a color enhancer and then impregnate the stone with a good quality stone impregnator. Quite possibly, you could try having someone (with proven experience) to come out and polish the stone for you. Messy and expensive. best of luck, Steven, USA
R1: Dear Jack: There are specific products called "color enhancers". You may want to check into the company listings in this site to find a manufacturer that makes one of them., Maurizio, USA

A 1108: I've laid Niagara marble for flooring of my house. After polishing, fine hair line cracks radiating in all possible directions just like a tree are seen. What could be the causes? Soudhamini, USA, Sept 24.
R2: The dimensional stability of the mortar / adhesive used to lay the stones may be suspect. The fact the cracks radiate in all directions suggest that the stresses are also in all directions. More information is really needed to solve this one such as how were the tiles adhered, what were they laid on, how thick are the tiles, have the tiles undergone any other treatment or exposure such as flooding, how long have they been down for. Regards, Jim, Australia,
R1: Wrong sub-flooring, or poor installation work. Ciao, Maurizio, USA,

A 1057: I'm tired of replacing and/or cleaning my carpet which was used to cover the natural stone on the stairs of our home. After removing the carpet however, the stone is in bad shape. There are holes from the nails, brown discoloration which has seeped in from the glue and other spots from the carpet which has been in place for many years. How can I clean and refurbish these natural stone stairs. The home was built in the early 1930s and it is beige in color. Carol, USA, July 30.

R1: You don't mention the kind of stone that was used, and the cleaning treatments do vary depending on the stone. Please stay away from any cleaning solutions that are acid based. If the stone is limestone, or marble, acid will have a very negative effect on the stone.  If the stains are surface stains, the stone can probably be refinished (i.e. sanded). Sometimes bleach will help. Sanding will also help with the nail holes, although some will probably need to be filled with a stone patch. Stains that penetrate the stone can often be lifted by using a poultice. The composition again varies depending on the stain.  Please check with your local tile store, or with a local fabricator to determine what the best course of action should be. JVC, USA.

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