RE-CRYSTALLIZATION-REVISTIED

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.

REACTION 1




REACTION 2






REACTION 3






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.

Designing a Sustainable(Green) Stone Floor Maintenance Program

Designing a Sustainable (Green) Stone Floor Maintenance Program
By Frederick M. Hueston PhD



Walk into any stone, terrazzo or janitorial chemical supplier and you will find an endless selection of cleaners, sealers, restorers, etc to keep you terrazzo and stone floors looking new. The problem is many of these chemicals can be harmful to the user, occupants and the environment. How does one design a program that is not only sustainable and safe but to also keep your terrazzo and stone flooring in like new condition?

Fortunately there is an effective way to not only maintain these surfaces but also to keep them looking new. The following guideline will show you how to develop a sustainable maintenance program. This is especially important for schools, hospitals and other buildings were children and people sensitive to these harmful chemicals are present everyday.

The dangers of floor strippers, finishes etc have been studied by many organizations including universities, etc. Here is a partial list of those studies

- Green Seal Report
Floor Care Products: Finishes and Strippers
www.greenseal.org/resources/reports/CGR_floorcare.pdf

-Safe and Effective Use of Floor Finish Strippers
Janitorial Products. Pollution Prevention Project
Sponsored by US EPA
www.wrppn.org/janitorial/factsheet/floor.htm

-Health Hazard Evaluation Report 95-0313-2589, University of Michigan Hospitals, Ann Arbor, Michigan

-NIOSH [1990]. NIOSH criteria for a
recommended standard: occupational exposure to
ethylene glycol monobutyl ether and ethylene
glycol monobutyl ether acetate. Cincinnati, OH:
U.S. Department of Health and Human Services,
Public Health Service, Centers for Disease
Control, National Institute for Occupational
Safety and Health, DHHS (NIOSH) Publication
No. 90–118.

-Ruth JH [1986]. Odor thresholds and irritation
levels of several chemical substances: a review.
Am Ind Hyg Assoc J 47:A142–A151.
WHO [1983]. Indoor air pollutants: exposure
and health effects. World Health Organization
Regional Office for Europe. WHO–EURO report
and studies no. 78, Copenhagen, Denmark.



Program Guidelines

Step 1. A good sustainable maintenance program starts with proper identification of the stone. Is it granite, marble, terrazzo or limestone? If it’s marble is it soft or hard? What type of finish does it have? Polished, honed, flamed, etc.? Is the type of stone the proper material for the traffic it is to receive? If not maintenance costs will be higher. If the answer to these questions are unknown, I suggest you contact a reputable stone supplier or restoration company to find out. A complete understanding of your particular stones characteristics is an absolute must for designing a sustainable maintenance program.

Step 2. Once the stone’s characteristics are identified determine the quality of the installation. Are the tiles flat and even? Do they contain lippage (uneven tiles). If so, proper maintenance may prove difficult. The floor should be ground flat, honed and polished using sustainable restoration procedures that utilize non-chemical methods. Are there any cracked tiles? Dirt will have a tendency to accumulate in these cracks. These tiles should be replaced or if replacements are not available at least repaired.

Step 3. What is the present condition of the stone? Has it been coated with waxes, acrylics, urethane or other coatings? If so these coatings need to be ground off to determine the condition of the stone as well as eliminate any toxic and unsafe properties. I have seen stone floors that appear to be in great shape until the coatings are removed to unveil a pitted, scratched mess. If a poor condition is found, complete restoration is necessary before a successful sustainable maintenance program can begin.

Step 4. Once the stone is restored to like new condition, then and only then will a sustainable maintenance program provide good results. This applies not only to the following program but any program. If the stone will be exposed to water, coffee, spills etc, an application of a an approved Green impregnator is recommended. These impregnators are designed to penetrate into the stone, without leaving coatings on the surface and still allowing the stone to transpire(breathe). They contain no harmful vapors or off gases when cured.


Step 5. Daily Maintenance

The three most important tasks that can be done on a daily basis to keep the stone looking new and extending the time before restoration is required are: Dust Mop, Dust Mop and Dust Mop. The most destructive material to most stone is sand, dirt and miscellaneous grit. If these substances could be eliminated, maintenance of the stone would be almost non-existent. A stone floor can never be dust mopped too often. Use a clean, non-treated, dry dust mop at least two to three times a day in high traffic areas and less often in low traffic areas. Walk off mats placed outside and inside an entrance will also eliminate a good portion of sand, dirt and grit. It takes approximately seven steps to remove all loose dirt from the bottom of ones shoes. Walk off mats also need to be removed and cleaned daily. Keep this in mind when purchasing walk off mats. Remember if sand, dirt and grit are eliminated there will be nothing left behind to scratch and dull the stone.

Note: Coatings in addition to potentially being hazardous contribute to accelerate wearing of the stone or terrazzo surface by acting as a magnet for dirt and debri. It has been shown in studies that a stone or terrazzo floor without any coating will be easier to maintain as well as more cost effective.


Step 6. Cleaning

All natural stone, both polished and unpolished should be cleaned daily in high traffic areas and less often in lower traffic areas. A clean rayon or cotton string mop should be used with cold to warm water with the addition of a quality Green Approved neutral cleaner or stone soap. Approved Green Neutral cleaners are defined as surfactant type detergents that have a Ph of 7. Acidic and alkaline cleaners should not be used. Be sure to follow the directions very carefully.






Why Does Stone Shine?

All stone is taken from the earth in a raw block form. This block is cut into slices that we call slabs. The slabs are then cut further to a smaller size such as a tile or countertop. It is then polished using a series of abrasive materials. The mechanics are relatively simple. A piece of stone is rubbed with a series of abrasives starting with a course grit size followed by
Finer and finer grit sizes. The scratch pattern left behind from one grit is removed by the next grit creating finer and finer scratches. This process is continued until the scratch pattern becomes microscopic. The process is similar to refinishing a piece of wood, starting with a course sandpaper and ending with a fine sandpaper. The shine is placed on the stone by continuing this abrading process using very fine powders. With sustainable(Green) restoration methods no chemicals are used.



Restoration

Periodically the stone will need to be restored. Perhaps you have not followed a proper maintenance program or the type of stone you have is not suited to the conditions it receives or for what ever other reason it is not responding to maintenance, then restoration is required. How often this will need to be done is difficult to determine. Generally if all the precautions above are followed, restoration may only be needed as often as once per year or as little as once every five years or so. The restoration process re-hones the stone to remove deep scratches and is then re-polished. Do not attempt the re-honing process yourself, this requires a great degree of skill and experience, please call a reputable restoration company who specializes in sustainable methods for this task.

Natural stone was the first building material used by man. Its care and maintenance is one of the oldest tasks performed by our ancestors and was maintained without any of today’s modern chemical products. The above guidelines were developed by our years of experience with this beautiful material and with the addition of sustainable practices will provide many years of beauty.


Written by

Frederick M. Hueston, PhD
Stone University
E-Mail: Fhueston@aol.com
Web Site: www.stoneuniversity.org