This is a great interview regarding the polishing process known as "crystallization." Not to be missed by anyone considering having their marble, limestone, or travertine floors polished. Must see!
 http://www.youtube.com/watch?v=mwkmDsBfzaI&feature=youtu.be

Choosing a stone care service provider.

Loved this little YouTube. Whole lot of truth packed into just a few minutes. Certainly true in my market area.


Topical Coatings vs. Honing and Polishing

From Stone World Magazine, Nov. 2004

The maintenance of stone flooring in the U.S. today is a million dollar annual business and continues to grow. Much of this increased growth results from the desire to maintain a highly polished mirror finish. As of this date, there are basically two methods to keep stone in this condition over the long term. One method is to place some type of a coating on the surface of the stone. These coatings can be natural or synthetic waxes, acrylics, urethanes and epoxies. The majority used today on marble are composed of acrylics. The second method used to maintain stone is to polish the stone with the use of abrasive diamonds and polishing powders. This method uses no coatings. It simply smoothes the stone to produce a high shine. The purpose of this study is to compare the advantages and disadvantages of these two methods as well as their labor and material requirements. (A third method is the use of flurosilicate compounds applied to the stone. This method is commonly called recrystallazation or vitrification and is applied as a final finish in place of powder polishing or it is applied on top of the polished finish for added shine. This study will not address this process.)
The maintenance procedures outlined in Figure 1 are typical. Frequencies will vary depending on traffic, type of stone and desired finish. Both procedures assume that the floor is in maintainable condition at the start of the maintenance program.

Method of study

In order to evaluate both methods, three commercial lobby floors were studied. In each case, the property began with a topical coating and shifted to a long-term maintenance procedure of polishing. All three cases have used both methods for a period of one year or more. Maintenance personnel and executive housekeepers were interviewed to obtain costs, advantages and disadvantages of both methods. Since hourly labor rates vary from state to state, this study will provide labor hours only.

Case Study #1

Property: Busy hotel lobby located near a major theme park. Floor Description: 12,000 square feet of Rosa Perlino marble in a Palandiana terrazzo pattern.
Usage: Very busy lobby. Traffic areas include large reception check in and four elevator banks. Floor is adjacent to a swimming pool area.

The floor has a topical coating. When the floor was completed, several coats of a carnauba-based sealer were applied. Maintenance is as follows:

1. Floor was dust mopped daily in the evenings during third shift.
2. Floor was wet mopped daily using a commercial, neutral floor cleaner.
3. Floor was spray buffed every night to remove scuffing, black heel marks and wear.
4. Floor was re-coated daily in heavy-traffic areas with a light coat of the carnauba-based sealer.
A total of 16 daily man-hours are required with this system. Comments on the maintenance program of coating from the staff and executive housekeeper were as follows:


  • The floors are very difficult to maintain. It appears to mar and scuff very easily.

  • Once floor is spray buffed, it looks great. But once traffic starts, the finish rapidly deteriorates.

  • The finish on the floor is turning yellow and becoming very dark and dirty looking.

  • The wax is accumulating in holes in the marble and turning black.
    A shift was made to a polishing maintenance program. The entire floor was stripped; the holes were filled and then honed and polished using standard marble polishing powders. Maintenance is as follows:

    1. Floor is dust mopped every evening.
    2. Floor is damp mopped three times per week using a stone soap.
    3. High-traffic areas are re-polished once every two weeks using standard marble polishing powders.
    4. As of this date no re-honing has been performed. Inspection of the floor and wearability indicates that honing of traffic areas will need to be about once per year.

    A total of 16 daily man-hours are required with this system. Comments from the staff and executive housekeeper on the polished program were as follows:


  • Our labor costs have been cut dramatically and the floor looks and stays clean longer.

  • Dirt doesn't seem to stick to the floor like it did before.

    Case Study #2

    Property: Busy hotel lobby, located next to major interstate exchange. Floor Description: 3,500 square feet of Rojo Alicante marble, 12- x 12-inch tiles.
    Usage: Busy hotel lobby floor. Constant traffic due to adjacent meeting rooms.
    This floor was initially stripped, and several coats of an acrylic floor finish were applied. Subsequently, maintenance procedures were as follows:

    1. Floor was dust mopped daily.
    2. Floor was wet mopped daily with a neutral cleaner.
    3. Once per month, the entire floor was re-coated with an floor finish. No spray buffing was performed between re-coatings.
    4. Once every three months, the entire floor was stripped and re-coated.

    In total, 4 hours of daily maintenance was required. Comments on the coating system from the staff and executive housekeeper were as follows:


  • The floor looks great for one day a month, immediately after it is re-waxed. During the remaining time, it looks just terrible.

  • The floor has a real plastic look; it doesn't even look like marble anymore.

  • The bellman carts are leaving marks on the floor all over, and the area in front of the reception desk is very dull.
    In order to change this hotel's floor to a polishing procedure, the entire floor was stripped to remove all the old wax. It was re-honed and then powder-polished using standard marble polishing powders. The maintenance procedure was adjusted as follows:

    1. Floor is dust mopped daily.
    2. Floor is wet mopped daily.
    3. Traffic areas are re-polished once per week using polishing powder.
    4. As of this date, re-honing is required about once per year of approximately 800 square feet.

    Total daily man-hours required are 1-4 hours.
    Comments on maintenance program after polishing from the staff and executive housekeeper were as follows:


  • Our floor looks like marble again, and the carts are no longer marking the floor.

  • Dust mopping and wet mopping are now a snap. The mop seems to glide very easily over the floor, and we are not picking up as much dirt as before.

    Case Study #3

    Property: High-rise residential complex lobby, located in Canada Floor Description: 1,000 square feet of a Nero Marquina and White Carrara in a checkerboard pattern.
    Usage: Very busy residential condominium with approximately 80 units.
    This floor had a topical coating of wax for the past several years, with the following maintenance program:
    1. Floor was dust mopped several times per week.
    2. Floor was damp mopped several times per week; daily during the winter months.
    3. Floor was spray buffed once per week.
    4. Floor was stripped and re-coated with an acrylic floor finish once every three months.

    Under this program, total daily man-hours were 1 hour.
    Comments on coating maintenance program from the staff and property manager were as follows:


  • Floor always looks dull and scratched.

  • I can never seem to keep up with the floor; it is always scuffing.
    To shift to a polishing maintenance procedure, the floor was stripped, ground flat, re-honed and polished using standard marble polishing powders. After that procedure, routine maintenance was as follows:

    1. Floor is dust mopped daily every morning.
    2. Floor is damp mopped once per week; daily in winter.
    3. Traffic areas are re-polished once per month.

    Total daily man-hours were reduced to 25 minutes.
    Comments on the polishing maintenance program from the staff and property manager were as follows:


  • Our floor is shiny again; it looks great.

  • I can't believe how easy the floor is to maintain; no more stripping and waxing.
    Figure 2 on page 97 illustrates the man-hours saved in each of three case studies that shifted from topical coatings to polishing. Based on this information, it is apparent that the honing and polishing method is more economical than the use of coatings on stone flooring. Labor costs are reduced by one-half or more.

    Material costs

    Cost for materials and consumption was difficult to obtain from the housekeeping staff. Based on estimates, material costs were insignificant compared to labor costs. The costs of polishing powders and diamond abrasive were slightly lower than the use of strippers and coatings.

    Conclusions and discussion

    Although costs are a major consideration when comparing the above two maintenance programs, it is also apparent that there are distinct practical advantages to the honing and polishing program as well as some disadvantages to the coating program. Coatings will mar, scuff and wear very easily. It is a well-known fact that there are no coatings currently available for stone that are harder than the stone itself. For this reason, coatings will scuff and mar much more than the actual stone. It is often argued that these coatings place a sacrificial layer on the stone protecting it from dirt and staining. Although this would make sense, in fact, the opposite is true. These coatings are soft and will attract dirt faster than a natural polish. This is easy to prove if one takes a section of stone floor and applies a coating, while on another section, performs a hone and polish. After one or two days, it will be discovered that more dust and debris is attracted to the coated surface than the honed and polished surface. It will also be discovered that removing the dust and debris from the coated surface is much more difficult. Coatings also will build on the surface, producing a plastic like appearance. Some coatings will also turn dark and yellow rapidly. This is especially true if the stone is exposed to ultraviolet light. The removal of coatings by the use of harsh strippers can also damage the stone. Many strippers contain sodium hydroxide, which can form what is known as an alkaline salt. These salts can penetrate into the stone and cause premature spalling. Some coatings may also block the breathing of the stone causing it to suffocate and rot. How does one protect the stone from staining if coatings are not used? Stone can be protected with products known as penetrating sealers or impregnators. These materials are designed to penetrate below the surface of the stone and keep water and debris on the surface. Since they are not coatings, they will not require repair. They do not, however, add gloss to the stone surface.
    Figure 3 outlines the advantages and disadvantages of the two maintenance programs studied. Although only three case studies were used, many con-tractors and maintenance companies were interviewed to obtain these conclusions. Those who use the hone and polishing programs said they are very pleased and will not return to the old strip-and-coat method. Those companies interviewed who use the strip-and-coat method were not aware that another program existed.
    Although this study shows that the polishing method is more economical, caution is advised. Each case must be studied carefully. Labor skill, budget requirements and existing condition of the stone must be evaluated before choosing the proper maintenance system. Those using marble polishing powders and diamond abrasives must be trained in their proper application. There are many quality coatings available that may be a good alternative to the above system, if these special skills are not available. It is advisable to contact a reputable stone maintenance professional for advice.

  • Doctored Stone

    Ever hear the phrase "Doctored Stone"?  Well, it's not because the stone is sick.  Some stones, mainly granite, don't naturally have deep colour when quarried and dressed. These stones would not be very popular if it was not for "doctoring".

    Doctoring it the process of applying dyed resins to the stone to achieve the desired colour. However, problems can arise down the line as the colour fades from UV exposure, or if a spill occurs with a solvent that will remove the dye, and leave a light spot, which looks like an etch mark that you see on marble. This problem is very common with black granite.

    The practice of "doctoring" is becoming quite common and many consider it to be unethical. This is because the consumer is not made aware of what they are buying, and the product is mis-represented, as the colour is not "true". Unfortunately, there is no standard current to limit this practice. The author will be working with the ASTM C-18 committe to change that, hopefully very soon.

    For more information go to:  http://www.doctoredstone.org/index.htm

    Crystalization, Micro-Recrystalization, Re-Crystalization


    RE-CRYSTALLIZATION-REVISTIED

     By Frederick M. Hueston

    The following is a reprint of an article I wrote back in 1990. I have edited some of the text to bring it up to date. My opinion on this process is still the same as it was in 1990. With that said there are some uses for this process, however care must be exercised in its use. Most of the damage I have seen since 1990 by this process results from the overuse of the product as well as the lack of trained personnel who apply it. The following reprint should give you some useful information on this process and the care that must be used when using it.

    To answer the problems experienced by customers who had dull and scratched marble. I tried to find the best and most practical solution to the restoration of their marble floors, walls, etc.
    Since this is a relatively small industry, there weren’t too many good sources. I did find some self-proclaimed “experts” who introduced me to the idea of “re-crystallization” as a safe and easy method of restoring and polishing marble and stone. They touted it as a time proven process which had its roots in the marble industry in Europe. It was alleged to be safe, easy to apply and was both slip resistant and permanent. In short, it was the perfect solution for most marble restoration and maintenance problems.
    Having been raised in the “old” school, I instinctively doubt anything that appears “too good to be true”. Experience has taught me that most of those “too good to be true statements” usually turn out to be exactly that!

    My business reputation is at stake whenever I recommend or use a product or procedure. I don’t take that responsibility lightly. So, I endeavored to get answers to some specific questions about this “re-crystallization” process (from the systems’ promoters).

    Question #1. Does the “re-crystallization” process contain waxes?
    Crystallization Answer: No.

    Question #2. Does the process allow the stone to breath (transpire)?
    Crystallization Answer: Vague generalizations and evasive replicas.

    Question #3. How does “re-crystallization” react with stone?
    Crystallization Answer: Evasive generalizations.

    These evasive non-answers surprised me. Perhaps there was something that these crystallization “experts” did not know---or did not want me to know.
    Though I am in stone consultation business, my formal education is in Chemistry. I had a natural curiosity about this wondrous process called “re-crystallization”. After all, if it worked, it would be great for my business. I determined to do some research on my own. Following is a summary of my research.

    TERMS

    The term “crystallization” is defined as the process by which a substance takes the form of a crystal structure. Most minerals are crystal shaped. The term “re-crystallization” implies that a substance has been crystallization a second time. In other words, changed from one crystal shape to another.
    In geology, re-crystallization takes place---under great pressure at high temperatures--- deep in the earth and over thousands of years. My research showed that the natural re-crystallization of minerals such as those found in stone is unlikely to be obtained with the so-called packaged chemical “re-crystallization method” being marketed by a number of companies. We can therefore assume that the term “re-crystallization” is used only as a marketing term.
    For the purpose of this article, we will use this term---re-crystallization---only as a description of the chemical process that follows.

    METHODOLOGY

    I obtained Material Safety Data Sheets (required by OSHA for all chemical products) from a good sample of “re-crystallization” product distributors.
    From them, I learned that all the “re-crystallization products contained a fluorosilicate compound. All contained an acid of one type or another and almost all contained varying percentages of waxes and acrylics.
    To understand how these ingredients react with marble, one needs to understand the makeup(natural composition) of marble, itself. The main constituent of marble is a compound called Calcium Carbonate (CaCO3). Calcium Carbonate, along with other accessory minerals, makes up what we know as marble.
    When an acid is dropped on marble it will burn and etch the surface leaving a pitted, dull spot. The reaction (Formula 1) illustrates what happens when an acid and marble come in contact with one another. The bond between the calcium and the carbonate is broken, producing water and carbon dioxide gas and the calcium carbonate is destroyed. In other words, acid destroys marble. All re-crystallization fluids contain acids.
    If you have any doubts, place a drop of re-crystallization fluid on a piece of marble, wait just 30 seconds and wipe it off. You will find that it has etched.

    FORMULA 1

    CaCo3 + HCL ---------------à Ca+ Co3 + H2O

    The main ingredient used in re-crystallization fluid is a group of compounds called flurosilicons. Three types of fluorosilicates can be found in re-crystallization fluids: (1) Aluminum fluorosilicate (2) Magnesium fluorosilicate and (3) Zinc Fluorosilicate.
    First used in 1883, flurosilicate compounds were used in an attempt to preserve marble statues that were crumbling. The effects of these compounds on stone were studied by several researchers and were found to have detrimental effects on the stone.
    It was found that flourosilicates deposit an enamel on the surface of the stone which completely blocks its pores. The stone suffocates, begins to break apart and rot. The results of these studies can be found in the book Stone Decay and Conservation written by Glovanni G Amoroso and Vasco Passins---ELSEVIER, Amsterdam, Lausanne, Oxford, New York 1983.
    The re-crystallization process uses an acid that attacks the calcium carbonate in the stone (Reaction 1). This reaction destroys the calcium carbonate and releases the calcium ion. The fluorosilicate compound then attaches itself to the calcium ion forming a new compound (Reaction 2 & 3). This new compound, calcium fluorosilicate forms an imperious film on the surface of the stone---totally blocking its pores.

    Based on the preceding facts. I have reached the following conclusions:

    FACT: Marble and stone must breathe (transpire). If the pores are blocked, moisture from the slab (condensation, etc.) will be trapped and the stone will begin to break down.

    FACT: The re-crystallization process places an impermeable coating of fluorosilicates on the stone, completely blocking its pores.

    FACT: Acid will destroy marble and stone.

    FACT: All crystallization fluids contain acids.

    The above facts are clear and incontrovertible evidence. What is even more startling are the dozens of marble floors and walls I have seen that have been destroyed by this process.
    Along with other responsible stone restoration firms in the industry. I urge anyone---even thinking about allowing a “crystallization” process to be used---to test the proposed products on a marble sample and judge the results for yourself. You will find the rapid deterioration of the marble frightening.
    For the names of responsible stone restoration firms, you are invited to write Building Stone Institute, Marble Care and Maintenance Companies, 420 Lexington Ave. New York, New York 10170.

    AN OPEN LETTER TO THE PEOPLE IN THE TRADE:

    The extensive marketing of restoration methods using “re-crystallization “ is a very serious matter for everyone in the industry. The alarming increase in the number of complaints regarding permanently damaged marble and other stone floors and walls is hardly conducive to increased sales and use of our fine products. This damage could have--- and should have---been avoided, I urge you to advise all your customers of the potential damage from any of these “re-crystallization” methods being marketed. Now that we know exactly what this so-called “re-crystallization” process is, we can answer the frequently asked question---Can a floor or wall that has been “re-crystallized” be saved?

    Here are some guidelines:

    First, determine that crystallization has actually been used. For a start, ask the customer. Some will tell you, others will flatly deny it, and still others simply won’t know.
    If the shine on the marble or stone looks wavy (acrylic looking) then you can be fairly sure there is some type of coating on it. It is relatively easy to determine the type of coating. To do this two chemicals are needed: (1) a commercial wax stripper and (2) methyl chloride (wood furniture stripper).
    Place a small amount of each chemical on the stone. If the commercial wax stripper removes the film then you are dealing with an acrylic type finish. Simply remove the finish with the stripper before starting the normal restoration or polishing process.
    If the commercial stripper does not remove the coating but the methyl chloride does, then you have a urethane based coating. Remove it with methyl chloride or grind it off.
    If neither one of these strippers removes the coating, the chances are it has been re-crystallized.
    Another reliable clue is the presence of swirls on the marble (or other stone). These are caused by the use of steel wool during the re-crystallization machining process.
    Make sure that before you attempt any polishing or grinding that you have determined the type of coating on the marble (stone). Be aware that there may be more than one coating---possibly an acrylic coating placed on top of a re-crystallization” coating, test several areas, to be sure.
    If it is discovered that the marble (stone) has been re-crystallized---can it be saved?
    This will depend on the severity of damage. For example. Travertine and Crema Marfil will exhibit damage almost immediately. Other stones, such as granite, will take longer. Still others will not show any apparent damage until the re-crystallized layer begins to wear off. It pays to become familiar with the various types of marbles and other stones.
    There are a few general rules to determine the extent of damage.
    These higher the CaCO3, the more destructive the re-crystallization will have been.
    The greater the number of applications of re-crystallization---over a period of time---the greater the chance of irreversible damage.
    The veining in some marble will be adversely affected first. If these veined areas crumble easily, when probed with a blunt instrument, the stone may be damaged beyond repair. If the amount of veining is not too extensive, it may be saved by filling with a poly resin such as Akemi.
    Perform several Patch Tests. Grind the stone and bring it up to a polish. If the stone polishes, the chance are it can be saved. CAUTION: make absolutely sure you have removed the re-crystallized layer entirely. We recommend starting with a 60 grit for most stones.

    A FINAL WARNING: some of the companies have begun to eliminate the term “re-crystallization” and are substituting “marble polishing” or “Vitrification”. Be cautious. Even if it carries the name of a nationally known chemical firm, check their claims. Ask to see the Material Safety Data Sheets. If the process contains fluorosilicates, do not use it. The hard sell “marketing” (selling franchises) of these products is bringing us very close to an epidemic of severely damaged marble (stone) floors. A few clients (who simply did not know better), having just installed brand new marble floors, have had terrible damage done to them. We all know that there is no such thing as a totally “maintenance free” floor. Marble, granite, slate---whatever---must be maintained. The type of maintenance varies with use. Obviously, an entrance foyer of a residence requires a very different maintenance schedule than the lobby of a downtown high-rise office building or a major hotel.

    Maintenance can be done quite simply, using recommended products and procedures. However, after extensive wear and tear---over a long period of time--- a client may wish to have professional restoration work done. This can best be achieved by employing a responsible firm using traditional methods. These firms will look at an installation and provide a written estimate not only of the costs involved (usually figured on a square foot basis) gut also the materials to be used. They should have their own equipment---and trained crews--- who have quality experience with the marble and other stone floors.
    Update: Since 1990 I have conducted several vapor emission test on marble and stone surfaces to determine if this process in fact does not allow stone to breathe. In my testing I have found that in most cases this process does in fact block vapor emission.

     

    Engineered Stone: What is it?

    Engineered Stone is not a popular term among it's manufacturers. They prefer the term "Quartz" which sounds much more natural. Ceaserstone, Stone Italiana, Smart Stone, Quantum Quartz, are a few of the more popular engineered quartz surfaces offered here in Australia.

    Engineered quartz slabs are all, for the most part, manufactured the same. They are all produced using the same production line equipment, either the Breton system which was created in 1977, or another system closely modeled after the Breton system. The ingredients are blended dry; approximately 93% crushed dry stone material and 7% dry polyester epoxy resin and dyes. Then it goes through the steps; mixing, blending, homogenizing, and molding. The slabs are then compressed with 100 tons of pressure and cured at a temperature of 90C for 30 minutes. Finally, there is a stringent regime of quality control to ensure the consistency in finish and colour, which is vitally important as consistency is the main selling point with engineered stone.

    If you would like to learn more about manufacturing you can watch the entire process here: http://www.youtube.com/watch?v=Tv6bhy4WT8g

    The engineered quartz finished product has some very attractive qualities for the tradesman, with a very high Flexural Strength (ASTM C-880), it will not easily break under stress or if it is mishandled, and a high Abrasion Resistance (ASTM C-241) means it is difficult to accidentally scratch. It also has a very low Absorption Rate (ASTM C-97), which means it will not easily stain and does not require sealing.

    There are many colours and textures to chose from, and the colour consistency is an attractive quality for designers, providing a low degree of risk...the client will get a bench top that looks exactly like the sample square they were shown. This cannot always be said for natural stone.

    Because the matrix is polyester resin engineered stone is not suitable for external applications, which will break down the resin due to UV exposure. Therefore, granite is recommended for external applications, and epoxy resin glue ups for all edgework.

    Engineered stone can also burn if hot objects are placed on them, like a frying pan from a hot stove, this is due to the resin binders which are not heat resistant. 

    Engineered stone will not etch because both the quartz matrix and the resin binders are not reactive to common acids. Even though limestone and marble is acid sensitive, the marble/limestone based engineered stone is not acid sensitive because it is so saturated with the resin binders, it actually changes the structure of the material- it's not a natural stone.

    In comparison, a true granite will not burn or etch and is almost impossible to scratch (depending on the type), but does require sealing in many varieties (all Juperanas, Kashmere, Ubatuba).

    Seams are easily disguised with engineered stone as the cuts can be very smooth, and joined together nicely. Epoxy seams appear to look better because the colours are easy to match and are already part of the material. Flat polishing seams can be a problem because the 3000 grit diamond polished finish will not match the factory finish, which has a freckled look. There is a three part kit one can purchase from the US to perform this, but it is $300 and a bit of a drama to do. This is also what makes scratch repairs such a problem on engineered stone. There is a way to return the diamond polished finish to a factory look, but that is a trade secret I will hang on to.

    Engineered stones can also develop "resin scratches" which appear to be small scratches in the stone, but are actually just in the resin binder, which is much softer. Tip: This is can be repaired by buffing with fine steel wool and acetone.

    CONCLUSION 

    All in all the appearance does have a manufactured look which is easily recognised to a discerning eye when compared to natural stone. It lacks the unique look of granite, that each granite piece is an original work of art from nature, and each bench will not look exactly like the house next door.

    The manufacturing however provides a great deal of control- you will know exactly what the bench will look like, and this offers security.

    The difference in regards to design is simply this: engineered stone is safe and natural stone is art, and art is objective. But you can love art to a greater degree.

    From a practical standpoint; both are similar in regards to durability, and engineered stone is much better for the fabricator due to the much lower breakage rate. Engineered stone will however burn, and it can discolour (I have restored some very badly stained engineered stone surfaces). Granite is superior in regards to longevity, will not scratch as easily, will not burn, and is not UV sensitive. But it also can stain and must be sealed with a high quality impregnating sealer.

    So there is a lot to consider. The choice will ultimately come from the client, and their being properly educated will help them get what they're after. I hope this will help.

    The Bare Truth about Stone Impregnating-Sealers

    The past 12 to 15 years witnessed the birth and phenomenal surge of a type of product for which nobody had ever felt the need for since mankind started to use stone, which means since the stone-age. All of a sudden, the last decade of the twentieth century brought about the awareness that, without it, we could no longer live.

    I’m talking about sealers for stone, also more appropriately referred to as “impregnators.”
    What happened, that caused this kind of frantic need for something that nobody ever needed before just about overnight?

    Ignorance happened!

    North America and most Northern European countries (that had no stone culture to speak of) were fascinated by a product that they always admired and craved for, but could never afford. The affordability factor, however, was not as much a cost issue, as it was an issue of lack of the specific craftsmanship necessary to process it. I’m talking about marble, limestone, granite, etc.

    Up until a couple of generation ago, stone tiles finished in the factory had not even been invented yet, and the slabs were delivered to the fabrication shop right off the gang-saw; that is, neither one of their two faces were calibrated and polished like they are now. It was the fabricator that had to process the surface of one side of the slab, by calibrating it (grinding), honing and polishing!

    All this without mentioning the machinery and tooling that were available back then! Marble and granite floors were made by using unfinished cuts of stone (the only ones available) that were set directly on the mud bed, then ground and finished on the premises (“grind-in-place” method). And that – all the processing, that is – is the main factor that makes the craftsmen involved understand stone.

    New processing techniques in the quarries and manufacturing plants, brought about an impressive reduction of costs, along with the great idea of ready-to-use products, such as polished marble and granite tiles, or almost ready-to-use, such as pre-finished marble and granite slabs.

    All of a sudden, the whole world was flooded with such enticing and legendary materials like marble, granite and other stones, which were offered in a way where expertise and craftsmanship were no longer needed (or were they still?) and at prices that were getting more and more affordable.

    Buying and selling stuff that’s manufactured in some mysterious way, in some far off factory, doesn’t make anyone any more intelligent about whatever it is that one’s trading. Processing it does. But it’s not the case here, remember?!… All the processing had been done by the factory; all we needed were just plain setters, or contractors that could use a saw and learn how to polish edges; and we could find plenty of them at a dime a dozen!

    Installing and cutting material that was made ready-to-use in some mysterious way, in some far off factory doesn’t make anybody anymore intelligent about such material, does it? Once again, only processing does. That’s why stone restoration / refinishing is the very pinnacle of all stone related activities: It’s the only one that actually processes the stone! And to do that, one must know stone.

    Are we beginning to get the picture? If you add to the mix the huge number of “new” stones that all of a sudden started appearing on the marketplace from all corners of the planet (and counting), and the almost total lack of self-regulation of the stone industry, which has been desperately trying to “keep things simple” with the consequence being that the situation is so confusing that nobody knows what actual stone one’s looking at, you have a big melting pot where only one ingredient is brewing: Ignorance. And to the best of my knowledge, nothing intelligent ever came out from it.

    Without knowing which one stone was good for what, and without any official guidance, wrong choices and specifications became the rule, rather than the exception (the exception, in fact, was a strike of pure luck in many instances), and problems of an unknown nature started springing up from all over the place, and still counting, of course!

    A solution was badly needed. But, alas, with the benefit of a precious few exceptions, the importers/distributors don’t know the first thing about stone. The fabricators are just about there themselves, since they get their stone “education” from salesmen and invoices. And the setters? What on earth have they got to do with stone knowledge? They only install it! What about the original producers? Well, quarry owners/operators usually know their own stone, period. So, if for instance you’re considering a marble quarry and processing plant, and you go back to the owners and question them why their marble “stains” so easily when it’s installed, say, in a kitchen, all they could honestly do would be to break the news that’s the wrong material for the wrong application, but such a “solution” – the only sensible one — would certainly not be satisfactory, would it? It would mean going back to school and learn something about stone, and nobody has time for that! Something “better” and “easier” was needed!

    It is the general perception that when a material turns out to be delicate and difficult to maintain, it needs to be “sealed”. The picture that most people have in their mind about a sealer and its expected performance is of some sort of “cocoon” that envelops the item to be preserved and protected, and turns it into an enjoyable, bulletproof material. With this picture in their minds, the major operators of the stone trade started soliciting chemists from all over the planet to find a sealer for stone that would solve all problems and could make them go away without stone knowledge. Of course the chemists – who don’t know the first thing about petrography – started out by asking the BIG QUESTION: “What seems to be the problem?” The answer came in like a unanimous choir: “STAINING!” Hearing that, off they went to work to solve a problem that they perceived as related to absorbency, due to the natural porosity inherent of all dimensional stones.

    And “The-miracle-in-a-bottle” made its trumpeted appearance on the international scene of the stone industry, and in a very short period of time became the “necessity” and what I consider one of the most overrated, over-promoted and over-applied (not to mention ill-applied) products in mankind’s history! A domestic company – one of the pioneers of the bottled solution – even called itself “Miracle” to anticipate what one could expect from their “one-medicine-cure-all” product!

    Did it work?

    When something sounds too good to be true, it usually is. What’s more, no matter how you slice it, there’s no substitute for true knowledge and professionalism. The much heralded “miracle-in-a-bottle” was not to be an exception!

    The was majority of the problems related to stone were stemming from their wrong specification, in part due to sheer ignorance about the real nature (geological classification) of the stone itself, and in part due to the total hostility at listening to reason displayed by all too many specifiers. No canned “solution” will ever be able to overcome that!
    So then, are all these sealers (impregnators) nothing but a bunch of useless marketing gimmicks?

    No, they are not. But before we go any further, let’s try to understand what a sealer for stone is, how it works and what kind of protection it offers.

    For starters, impregnating sealers are two-part products: one is the carrier, which could be mineral solvent or just plain water, while the other part is the solid, a resin of sort that will do the actual sealing. The most popular resins are silicone, silane, siloxane, ester epoxy, fluorocarbon alphatic (a.k.a. fluorochemicals). Currently, the latter are recognized as the best and longer-lasting performers, plus they are the easier to make in a formulation that can be carried by water, thus eliminating the use of volatile and hazardous mineral solvent.

    Second and very important, is the fact that sealers for stone are not topical products like any other sealer people are familiar with. In fact, they are below-the-surface sealers. The first implication of this is the fact that a sealer for stone will not offer any protection to the surface of the stone itself from wear and tear or chemical attacks. The second implication is the fact that a sealer for stone will not alter in any way, shape or form the original finish on the stone surface that was either produced by the factory, or by a stone refinishing contractor. The most important phase of the application of a sealer for stone is to make sure that every residue of the product is thoroughly removed from the surface of the stone, before it has a chance to dry. This means that, at the end of the application of the sealer, the surface of the stone will be as bare as it was before the sealer was applied to it.

    That being said, let’s now elaborate the principle of a below-the-surface sealer. The product goes inside the stone; the carrier (water or mineral solvent) evaporates, while the solid part (the resin) will remain inside to clog the pores of the stone to an average depth of approximately 1mm. (The more porous the stone is, the deeper the impregnator will go.) Now how does an impregnating sealer go inside the stone? Quite simply, by being absorbed by it: the product is applied on the surface of the stone, which in turn will absorb it.

    So far, so good! But… Mother Nature never meant to make things simple and equal. While every stone this side of mono-mineral rocks (e.i.: most gemstones) are absorbent to a certain degree, when their degree of absorbency is 0.2% by weight or less, it will hardly absorb anything: the surface tension of the stone will not allow anything in, if not under extreme circumstances. What this translates into is the fact that many stones will not absorb the sealer, but on the other hand they will not absorb any staining agent, either. Hence, the application of an impregnating sealer to those stones is a total waste of time, money and also with the distinct possibility of the development of future “mysterious” problems if the residue of the product (actually 100% of it!) will not be completely removed, which is seldom the case.

    Another factor to be taken into consideration is the way the surface of the stone is finished. The absorbency rate of stone is measured by the increase of the weight of a given sample after being totally immersed in water for a pre-determined period of time. The percentile represented by the difference in weight before and after is the rate of absorbency of the given sample of rock. But… the sample is just a rough piece of rock with all its pores open to the max. However, stone is not delivered and installed in that way: one face of the slab or tile will be finished by the factory, either to a polish-finish or hone-finish or whatever. This can make a huge difference; for instance, if we take travertine, we can see that its absorbency rate is on or around 0.4-1.0%. It’s a rather dense stone, but in its natural state it will absorb liquids – even if not much; but once it’s finished either polished or honed or even tumbled, the surface tension of travertine will become so tight that liquids will rarely go in – including the sealer, of course. Most marbles have absorbency rates between 0.1% to 0.5%. When highly polished their surface tension will not allow any liquid in. What’s interesting noticing, however, is that certain hone-finished marbles will absorb some liquid. Why is that, if on paper they are less absorbent than travertine? Because for some strange physical phenomenon, the surface tension of travertine is higher than the surface tension of the average marble, and therefore, in real life term, travertine will effectively absorb less than marble.

    Yet another factor to be taken into consideration is if the stone is installed on grade and/or outdoors. After some serious investigation and testing we reached the conclusion that the application of an impregnator to outdoor installations is not only totally useless, but, in all too many instances, deleterious to the stone, as well. Stone needs to breathe to endure; it’s a scientific fact that nobody debates. While we’re certainly not generalizing this scientific true (stone doesn’t need to breathe all the time: it must be able to breathe only if the circumstances demand it) the typical case when a stone need to breathe is when set outdoors, especially when installed on grade, which is often the case. That is the reason why all manufacturers of impregnators but me flaunt the “fact” that their impregnator allows up to 95% vapor transmission.

    Why don’t we at MB Stone Restoration & Supply do the same?

    Because, no matter how hard we tried, we could never find a tool, a device, a contraption or what-have-you that would enable us to conduct any such test on a piece of stone treated with our impregnator.

    Why? Because such a device simply does not exist, we believe!

    So then, how did our competition ever come up with such bold statement? Well, for starters there’s the magic expression “up to” before the 95% thing; second, if there’s no such a thing like a device to measure the vapor transmission ability of a certain impregnator, there isn’t such a device to verify their statement, either!

    It is a fact, however, that nobody is ever denying that an impregnator, while allegedly allowing for “up to” 95% vapor transmission, will slow the transmission of the vapor down dramatically. It makes sense, if you think for a minute.

    Now consider this: certain stones set on grade (outdoors or indoors it doesn’t matter) will react funny to vapor transmission coming from beneath them, whether they are sealed or not. So we can have efflorescence, warping, oxidation and even spalling. (Needless to say, if they are sealed the problem will arise even sooner.) But there are certain other stones that will withstand the migration of moisture through their core; i.e.: many a travertine, certain specific slates, many a sandstone, many a limestone, most true geological granite and many a mercantile granite, etc., without any major problem. As long as they’re left in their natural state, though!… In other words, if the moisture developing under those stones has the chance of migrating through them at its natural speed rate, nothing bad will happen. (The formation of some mold and mildew, maybe, especially under humid climate conditions; but it’s no big deal.) But if you dramatically slow down the passage of the moisture by applying an impregnator to the stone, then all bets are off, and even stones that would be problem-free on that department, could become problem-laden and develop unforeseen phenomena with not easy solution, if any at all.
    Let’s make no mistake absorbency of stone is a fact indeed, and, under certain circumstances it could represent a problem (although not a dramatic one; after all removing a stain from a stone is usually child-play). Good-quality impregnating sealers can help a great deal. But it must be understood that the reduction of the natural absorbency of the stone is the only feature that anybody can expect from a sealer. No “cocoon” and no other “protection” whatsoever. What’s more, we must above all learn when a sealer is needed or is useless. As further examples, a granite (true geological granite, that is) countertop fabricated for a kitchen usually does need to be sealed. But let’s understand that the sealing is required because of the environment the stone is installed within, not just because of the stone itself. In fact, it wouldn’t make much sense to seal the same granite installed on a formal living room, or a foyer floor (where the likelihood of staining is minimal); as it would make no sense whatever to seal the same granite installed on the walls of a condominium lobby, where the likelihood of staining is totally inexistent. Remember, stone is a product of nature, and the more you leave it alone and don’t tamper with it, the better it is for it! It’s a scientific fact, not this writer’s opinion.

    However, what’ most important is the fact that true granites are no more than a dozen stones; a tiny minority compared to the over 2000 type of stones that are traded as granite! Take a couple of dozen of them out as next of kin of granite, and what you’re left with is a huge number of stones with no relation whatsoever to granite and to each other. Many of them have absorbency rates coming in at 0.2 or less. (Some as low as 0.01!) No staining will ever occur to those stones and, of course, they will never absorb any sealer!
    But what about all those stains on marble and travertine?


    They are NOT stains: they are rather “stains”, that is actual surface damage that only look like stains (see our other helpful hint about stain removal), and no sealer on the marketplace claims to even begin preventing them! As a matter of fact, most marbles and travertine are very dense stones – contrary to popular misconception. Their absorbency is very limited and, in most instances, they don’t need to be sealed. Green Marbles (Serpentinite) do need sealing, when installed in an environment where staining is likely to happen, however.

    Is there any easy way to find out if a given stone needs to be sealed?

    Yes: just spill a few drops of water on its surface, let it dwell for 5 minutes or so and then wipe it dry. If under where the water had been sitting you will notice a darkening of the stone (it will disappears once the water will evaporates) it means that some of it was absorbed; therefore, if the stone will be installed in an environment prone to staining, the application of a good-quality impregnator will be in order. If not, don’t bother.

    In conclusion, like I had the opportunity to state in my other and more formal editorial about stone impregnators, when properly and intelligently applied (stone is a natural product, and no blanket rule ever applies to a natural product), they do solve the problem of medium absorbency stones when installed in an environment where staining is a distinct possibility, but that’s all there is to them. Once again, buying into the possible suggestion that a sealer can do more than that, will inevitably lead to wrong decisions, which in turn will only lead to disappointment.

    © ITCS & Maurizio Bertoli – 1996-2008
    Maurizio Bertoli is the founder of MB Stone Restoration & Supply, Inc. (www.mbstone.com) and the co-founder and Director of Education of the International Training Centers for the Stone industry (ITCS).