RE-CRYSTALLIZATION-REVISTIED

                                By Frederick M. Hueston, StoneForensics.com

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. In addition keep in mind that the chemicals contained in this process are not sustainable(Green) and can be extremely harmful to the user as well as occupants of the building it is used in.

     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.

                                                                  REACTION 1

Ca CO3 + ----------------> Ca++AC  +H2O + CO2

                                                                         REACTION 2

MgSiF6. H2O + Ca++ ------------------>CaSiF6

                                                                   REACTION 3

                                    ZnSiF6.H2O + Ca++ -------------------->CaSiF6

     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.

OXIDATION OF ELEMENTAL IRON WITHIN STONE SURFACES(YELLOWING OF STONE SURFACES)

OXIDATION OF ELEMENTAL IRON WITHIN STONE

SURFACES(YELLOWING OF STONE SURFACES)

Frederick M. Hueston 

Sitting in my office one morning I received a call from a very upset homebuilder. He told me he was building a

two million-dollar home on the west coast of Florida. They installed nearly 3500 square feet of a white statuary

marble tile. Over the weekend one of the water pipes broke in a bathroom and completely flooded the home.

They managed to vacuum all the water and started to access the damages. Beside warped wood, soaked drywall

and an irate homeowner the marble tile seemed fine except for some minor water spotting. After several weeks

the replacement of warped wood and drywall began and then he noticed the white marble tile turning yellow. At

first he thought it might be some type of residue so they tried cleaning the marble with some bleach and waterthe

yellowing was still there. The homeowner was getting more and more irate and was threatening a lawsuit.

He asked if I could get down there right away and take a look at the marble and suggest what to do.

The above story is not uncommon and is a frequent occurrence on white marble tiles exposed to flooding. Can

the yellowing be removed or does it need to be replaced? What causes the yellowing and will it get worse. The

following is an explanation of yellowing in white marble and some techniques that may help.

Why Does White Marble Turn Yellow?

The problem of yellowed white marble is not uncommon. All over the United States I have encountered yellow

to brown marble. Although flooding is a common cause there are several other reasons this color change will

occur.

1. Improper Maintenance- As marble wears the highly polished surface begins to disappear. The wearing of

this polish causes the surface to become rough and is a magnet for dirt. If improper cleaners are used, this dirt

begins to accumulate in the pores of the stone and will turn yellow. It is surprising how often I have seen this

condition on marble. Upon investigation in these cases I have found dirty mops being used. Mops used to

clean the restrooms and/or kitchens were also used to clean the marble floors. Floors are mopped with strong

cleaners or wax cleaner combinations or with no cleaners at all.

Cure: If you suspect yellowing due to improper maintenance the marble tile will have to be cleaned with an

alkaline marble cleaner. I would suggest a heavy duty stone cleaner. Be sure the stone cleaner you buy is

alkaline and not an acid since acid cleaners will dull the polish. Apply the cleaner to the marble and scrub with

a soft brush. Be sure to rinse the floor throughly. It may be necessary to repeat this procedure several times to

remove all the imbedded dirt. If after cleaning the marble is dull I would suggest re-polishing and an

application of a good quality penetrating sealer(impregnator). If after several cleaning’s the yellowing is not

removed than proceed to the next cause.

2. Wax Build-up or Coatings- Many marble floors are coated with waxes, acrylics, urethane and other coatings.

Many of these coatings are not specifically designed for use on marble floors. Some of these coatings are of

poor quality and will begin to yellow. It is not uncommon for coating to be applied in multiple coats. As the

coating builds up it becomes soft and dirt is easily embedded in the soft layer. These coatings require frequent

stripping which is often neglected.

Another process used for polishing marble floors is a process known as recrystallazation. If this process is

applied to a white marble floor that contains moisture it will turn the marble yellow. If this process is to be

used, it is important that the marble be dry.

CURE: To remove yellowing due to a wax or coating buildup the marble will need to stripped with a

commercial wax stripper. I would strongly suggest using a stripper manufactured by the same company as the

floor wax or coating. This will help avoid incompatibility problems. Follow the directions on the stripper’s

label and be sure to rinse the floor throughly. These strippers often require the use of abrasive pads which can

scratch and damage the marble surface. Before undertaking the entire project perform a small test to determine

results.

If the marble tile has been recrystallized, it will be necessary to remove the recrystallized layer. This layer can

often be removed by polishing the tile with a powder marble polish containing oxalic acid. Apply the powder to

the tile, added water and work into a slurry with a hog hair pad and a standard buffing machine. Continue to

work until yellowing has disappeared. If this technique fails then the tile will have to be re-honed. It is strongly

suggested that the polishing and honing procedure be performed by trained individuals. If these techniques fail

to remove the yellowing then proceed to the next cause.

3. Iron Staining- Many white marble tiles contain naturally occurring deposits of iron. Iron is a mineral found

in stone and can occur randomly throughout the stone. If iron is present in the marble tile, it will begin to

oxidize when exposed to water or other oxidizers such as acids and household bleach. White marble tiles can

remain on a floor for years without yellowing then over time may slowly turn yellow and in severe causes may

turn completely brown. This oxidation process is accelerated when the tile is saturated as in the flood in the

above example. This process of oxidation is similar to the rusting of metal. If you expose a brand new nail to

water and air it will turn brown and rust. The same process is occurring with the iron in the marble. If water

and/ or air is eliminated the iron will not oxidize. This is the reason certain white marble suddenly turn yellow.

The process is difficult to reverse and replacement of the tile may be necessary. The following stain removal

technique has proved successful in several cases. Before testing this procedure it is important to first determine

if iron is the cause.

Testing for Iron:

1. Before assuming the marble is yellowed due to iron be sure to attempt cleaning and stripping as outlined in

#1 & 2 cause above. If these procedures fail then testing for iron will be necessary.

2. If a flood has occurred or excessive water was used first check the water for iron. There are several

inexpensive test kits available that can be used to check the iron content in water. Check with your local

plumbing supply store or store carrying water softening supplies. If any amount of iron is detected then it is

possible iron has entered the stone through the water supply. To eliminate the iron there are chelating chemicals

that can be added to the water to prevent the iron from staining. This is very important if the tile is cleaned withthis water.

3. If the water contains no iron and even if it does the tile should be checked for iron content. Remove one tile

and contact a testing lab and have them analyzed the tile for total iron. If there are spare tiles that have never

been installed also have them tested for total iron. If iron is present naturally in this stone, it will probably be

detected in the spare tile. If the results return with iron present then the following procedure should be tested.

4. Check the tile for moisture. A moisture meter is a useful instrument that can be employed to check the tile

for moisture. If the tile contains water, it is very possible that iron is beginning to oxidize.

Removing Iron Staining:

1. Prepare a solution of water and the following chemical: Sodium Hydro sulfite and Sodium Metabisulfite.

These chemicals are available in a product called Iron-Out(TM) from your plumbing supply or home center.

Mix a solution in water and apply to the effected tile. Allow solution to soak into tile and keep wet for several

hours. Do not allow solution to dry. After several hours pick up excess solution with a wet vacuum and rinse

throughly with water and a chelating agent such as EDTA. Be prepared to repolish the marble since these

chemicals can cause etching.

2. If the above procedure fails than prepare a poultice with diatomaceous earth and the Iron Out(TM). Mix the

poultice into a thick paste and apply to a small area. Cover the poultice with plastic and allow it to sit covered

for 24 hours. After 24 hours remove the poultice paste and rinse the area with water and a chelating agent. If

the stain is removed, the entire floor can be treated. If the stain still remains then replacement is the only

solution.

3. There are also some new chemicals that are available which contain Ammonium Thioglycolate which look

promising for removing iron oxidation. Check with several stone maintenance supply companies.

Before the above procedure can be performed, it is important that the effected tiles be dry. If water or moisture

are still present, oxidation of iron may continue

The yellowing of white marble is a common problem. New installations should be sealed with a good quality

penetrating sealer(impregnator) Which will help prevent oxidation of the iron by eliminating moisture.

The above procedure has proven successful in some cases of iron staining however if the outlined test does not

produce the desired results I would recommend replacement of the effected tiles.

Written by:

Frederick M. Hueston

Stone Forensics

www.stoneforensics.com

Black Granite Fading

Black Granite Fading

By Frederick M. Hueston

I have received numerous calls lately concerning the fading of black granite counter tops.
The most common complaints seem to be on Absolute Black, Black Galaxy, Zimbabwe Black and a few others.  I have heard many fabricators try to blame the fading on the mis use of cleaning chemicals, acids etc.  While one should not use inapropriate chemicals on granite surfaces, this is not the reason for the increase in black granite fading.

Why does black granite fade?
The answer is, black granite should not fade. Black granite imported from Asia and India is sometimes doctored with dyes and oils to darken the surface. Dyes can include home made blends such as charcoal and linseed oil.  Pre packaged color enhancers are also used to darken granite. The fading is nothing more than the dyes and oils being removed. Of course the wrong chemical will take the dye out faster but I have seen many of these dyes removed using simply water and a mild cleaner.


                   
Here we see fading of a dyed Black Absolute Slab

Dye dripping down the sides of black granite

This picture was taken in India showing a worker applying dye to the granite.
Testing for Dyed Granite
Before purchasing a granite slab perform the following test to find out if it has been doctored.
Take a clean white rag and apply some acetone to the surface of the granite. If any residue or black color is observed on the top, do not accept it, it has been dyed. If you get no dye from the acetone then take some MEK(Methyl Ethyl Ketone) and apply to a different part of the slab. If you get any color transfer the stone is dyed. These chemicals can be purchased at most home improvement or paint supply stores.
Can Dyed Granite Be Repaired?
The reason granite is dyed is that its natural color is gray and it doesn’t have that deep black color that some black granites have. For this reason many factors use deceptive methods to doctor these slabs pawning them off as deep black granites.
Unfortunately, there is no fix. Other than to dye the granite again.

In addition to dying many types of granite are also injected with resins, which can also darken granite. For further information on the resining process see my article titled  Resin Slabs, The Good, The Bad and The Ugly at www.stoneworld.com.

Fred Hueston
321 514 6845
www.stoneforensics.com

The Coronavirus and Your stone Countertops

The Coronavirus and Your Stone Countertops

By Frederick M. Hueston

stoneforensics.com

The entire world is in a panic over the new coronavirus, and as a stone expert, my phone is ringing off the hook with questions. Can the coronavirus survive on my stone countertop? If so, for how long? What do I use on my stone to properly kill the virus?

As of this writing, there are many unknown facts about the coronavirus, however, there are several studies that have looked at these questions in the past. One such study was recently published in The Journal of Hospital Infections entitled Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents. Following is a brief summary of this research.

How long can the coronavirus survive on stone surfaces?

The short answer is, we don’t know, however similar viruses, such as SARS and MERS, can survive for up to 9 days. The common flu virus can last up to 48 hours on a stone surface. Additional studies have shown that the virus can last for over a week but seems to have a shorter lifespan at temperatures over 86 degrees F. Of course, stone surfaces would rarely reach those high temperatures in an average kitchen environment.

Can you get the coronavirus by touching a contaminated stone countertop?

Again, there is not enough information or studies that confirm that the coronavirus acts similar to other viruses, however, some studies are showing that the virus can be killed with standard household disinfectants. One study showed that disinfectants with 62-71% ethanol, 0.5% hydrogen peroxide or 0.1% sodium hypochlorite (bleach) can inactivate the coronavirus within a minute. Although the study shows that the coronavirus is similar to SARS, it is not yet clear if the coronavirus will act the same as SARS. So, can you get the virus by touching a contaminated stone surface? According to The Centers for Disease Control and Prevention (CDC), touching a surface is not believed to be the main way the virus is transferred. The most likely way it is spread is from person to person from coughs and sneezing.

How do you properly disinfect your stone surface to kill the coronavirus?

Currently, it is believed that most household disinfectants can kill the virus, however, I have discovered that many people do not know how to properly use these sanitizing solutions. Many people will spray and immediately wipe a disinfectant. This method will not kill the virus. The disinfectant should be allowed to dwell on the countertop for 3-5 minutes to be effective. You can also make your own disinfectant by mixing one half rubbing alcohol with one half water. Spray the disinfectant on the countertop and thoroughly wet the surface. Allow the solution to sit for 3-5 minutes. Rinse with clean water and then dry with a microfiber cloth.

The best advise is to keep your stone countertop clean is by following these simple steps.

To keep your granite in tip-top condition, a few simple maintenance procedures are necessary. For best results, they should be followed very closely.

1. Clean the countertop daily with a soft white cloth and a neutral cleaner or stone soap. These products are available at most stone and tile suppliers.

2. It may be necessary to buff the countertop with a clean white terry cloth towel if streaking occurs.

3. Once a week, clean with a disinfectant

4. All granite countertops should be sealed.

5. If the countertop becomes stained, immediately blot the spill with a clean paper towel.

According to the World Health Organization (WHO) the best way to avoid the coronavirus is to:

1.      Wash your hands frequently. Regularly and thoroughly clean your hands with an alcohol-based hand rub or wash them with soap and water.

2.      Maintain social distancing. Maintain at least 1 meter (3 feet) distance between yourself and anyone who is coughing or sneezing.

3.      Avoid touching eyes, nose and mouth. Hands touch many surfaces and can pick up viruses. Once contaminated, hands can transfer the virus to your eyes, nose or mouth. From there, the virus can enter your body and can make you sick.

4.      Practice respiratory hygiene. Make sure you and the people around you, follow good respiratory hygiene. This means covering your mouth and nose with your bent elbow or tissue when you cough or sneeze. Then dispose of the used tissue immediately.

5.      If you have fever, cough and difficulty breathing, seek medical care early. Stay home if you feel unwell. If you have a fever, cough and difficulty breathing, seek medical attention and call in advance. Follow the directions of your local health authority.

A Final Word

As the coronavirus spreads, there is sure to be misinformation on how it spreads. The best way to the truth is to keep an eye on the CDC and WHO websites as well as your local health department.

References

1.The Journal of Hospital Infection; Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents; G. Kampfa,∗,Correspondence information about the author G. Kampf; D. Todtb; S. Pfaenderb; E. Steinmannb

https://www.journalofhospitalinfection.com/article/S0195-6701(20)30046-3/fulltext

2. World Health Organization-https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public

3. The Center for Disease Control and Prevention- https://www.cdc.gov/