Are Floor Strippers Safe

Are Floor Strippers Safe

 

By Frederick M. Hueston

 

Almost all schools systems and public buildings apply acrylic finishes to there , terrazzo and stone flooring to keep them shiny and looking clean.  Often these finishes have to be striped off and a new finish applied.  The strippers that are used to remove these acrylic coatings often contain hazardous chemicals that are harmful to humans, animals and the environment.  The following information will explore how dangerous these strippers are and offer an alternative.

 

I examined the Material Safety Data Sheets(MSDS) of over 20 popular strippers used to remove acrylic floor coatings. I found that there are several common ingredients found which are the following:

 

Monoethanolamine

Butoxyethanol

Ethanolamine

Ethylene Glycol Monobutyl Ether

Sodium Hydroxide

 

I next examined the dangerous of these ingredients

 

Butoxyethanol

 

Butoxyethanol goes by several names including ethylene glycol monobutyl ether, ethylene glycol butyl either, ethylene glycol n-butyl ether, Butyl Cellosolve, butyl glycol, butyl oxitol,glycol butyl ether, Dowanol EB, Gafcol EB, poly-solv EB, and Ektasolve EB.  If you see any of these ingredients on an MSDS for the stripper you are using you are dealing with Butoyethanol.

 

Butoxyethanol is used  in many products other that floor strippers, including  paints, varnishes,  lacquers, paint thinners, agricultural products, herbicides, silicon caulks, cutting oils, fabric dyes and inks and household cleaners and even in some floor cleaners.

 

Butoyethanol is a dangerous chemical in many ways. It can pass into the air from water and soil as a vapor. This means that the vapors are emitted when you  mix your strippers in water and apply them to the floor.

 

Butoxyethanol is very harmful to humans and has been shown in laboratory testing to cause the following:

 Irritation of the nose and eyes

Headaches

A metallic Taste

Vomiting

Breathing problems

Low blood pressure

Lowered levels of hemoglobin

Blood in the urine

Metabolic acidosis

Birth Defects

Kidney and liver damage

 

Butoxyethanol and the Environment

 

Butoxyethanol can be absorbed by soil and can make its way into the water supply.

 

 

The warnings on many labels of floor stripper containing Butoxyethanol say the following:

 

Avoid breathing vapor or mist.
Avoid contact with eyes, skin and clothing.
Keep container closed.
Use only with adequate ventilation.
Wash thoroughly after handling.
Keep away from heat and flame.

 

Do you want this harmful chemical used in your school or building?

 

 

Monoethanolamine

 

Monoethanolamine is another common chemical found in strippers.

 

Monoethanolamine also goes by several names such as  Colamine, Glycinol, Olamine, Ethanolamine, 2-Aminoethanol, 2-Hydroxyethylamine, beta-Ethanolamine and beta-Hydroxyethylamine.

 

Some of the potential health effects include the following:

 

Extremely harmful to the eyes.

Harmful to lungs, skin.

Tissue damage can occur around mucus membranes

Can cause burns on the skin

Maybe toxic to Kidneys, Lungs, liver and central nervous system.

 

Monoethanolamine in also combustible.and corrosive

 

Harmful to animals and the environment.

 

Monoethanolamine can produce very harmful byproducts due to degradation in the environment.

 

Sodium Hydroxide

 

Another chemical found in many strippers is Sodium Hydroxide.  Sodium Hydroxide

Is commonly known as lye. Any one who has ever worked with this knows it can easily burn you skin, not to mention what it can due to your eyes and mouth.  It is classified as a poison and is very corrosive.

 

Since it is a poison it is harmful to animals and fish.

 

 

Conclusions and Alternatives

 

As you can see the common chemicals found in numerous stripper formulas are not safe for humans or the environment and cannot be classified as a sustainable practice if using them.

 

The good news is there are alternatives to these chemicals.

 

Acrylic coating on terrazzo and stone flooring can be removed mechanically with abrasives using no chemicals other than water.

 

Many Chemical companies are manufacturing strippers that are safe to work with and are Green Certified.

 

 

 

 

 

 

 

 

 

 

A New But Old Polishing Procedure for Natural Stone/Terrazzo Flooring

A New But Old Polishing Procedure for Natural Stone/Terrazzo Flooring

By Frederick M. Hueston 

Putting New and Old in the same sentence is somewhat of an oxymoron. But in this case  both of these adjective apply. What I am talking about is a polishing system for stone flooring that was used many years before chemicals came into existence and is now fast becoming  the preferred method specified by architects and others.   The word   “Green” has entered our industry and I am finding that many projects across the US are now specifying that a green and sustainable restoration process be implemented in restoring both natural stone and terrazzo surfaces.   This article will present not only what is sustainable but will give you an alternative to traditional polishing methods that is fast becoming the preferred method.

 

What is Green?

Everywhere you look individuals, government agencies, universities and schools and even private businesses are going green.  As we hear news about global warming and how we are polluting our own environment, it is of utmost importance that we all do our part in saving our planet not only for our present generation but for generations to following.

What Does Going Green Mean?

The term Green or Going Green has entered our vocabulary but few really know what the term means. Going Green is principles that minimize the use of nonrenewable resources and seek to prevent air, water and ground contamination and other activities that degrade the environment.  According to The US Green Building Council worldwide buildings account for 17% of fresh water withdrawal, 25% Wood Harvest, 33% CO2 emissions and 40% material and energy use.

Going Green is simply changing the way we build, operate and maintain buildings to reduce the negative impact it is having on our environment.

Many small businesses feel that they are too small to make an impact on the environment. Even individuals feel the same. Take a look at the following facts and you will see this is simply not true.

·        A single quart of motor oil, if disposed of improperly, can contaminate up to two million gallons of fresh water.

·        A 1/32" leak in a faucet can waste up to 6,000 gallons of water a month, or 72,000 gallons a year.

·        Americans throw away 25 billion Styrofoam coffee cups every year, and 2.5 million plastic beverage bottles every hour.

·        The amount of wood and paper we throw away each year is enough to heat 50 million homes for 20 years.

 

And the list goes on and on.

 

 

Stone Restoration and Green

Traditionally the  restoration, repair and maintenance of stone and terrazzo surfaces use chemicals that are harmful to the environment and to people in general. Chemicals such as polishing compounds contain harmful acids. Solvent based cleaners and sealers emit harmful VOC’s. Not to mention the carcinogens and toxic effects many of these chemicals have on humans.   The procedures used to restore stone surfaces also produce a copious amount of waste and use large amounts of fresh water.

I am currently working with a stone restoration company that is taking steps to eliminate all these harmful chemicals and processes. This company has developed methods to restore , repair and maintain stone surfaces using no harmful chemicals. As matter of fact the restoration and polishing of marble, granite, limestone and terrazzo uses no chemicals at all. Here is a summary of their process

The floor is ground and resurfaced using a fixed diamond abrasive and water. These abrasives are similar to sandpaper but differ in that there is no grit removed or left behind on the floor. The diamond abrasive is fixed to a pad. There are no chemicals used at all.

The water used will be recycled and reused in a specially designed system.

To polish the stone or terrazzo super fine abrasives are used. These abrasives contain no harmful chemicals.

Many stone restoration and janitorial companies are also using floor finishes to achieve a high luster on the stone or terrazzo surface. In addition to these finishes containing chemicals that are harmful to the environment. They also have a negative impact on the esthetics of the surface in the following ways:

-Most finishes used on stone and terrazzo are soft and tend to show wear and scuff marks in a very short time. This increase the amount of maintenance as well as cost for daily maintenance

-All floor finishes at some point will need to be stripped off. The chemical strippers used are caustic and can cause damage to the stone or terrazzo, not to mention the environmental impact.

-The old finish once it is removed will need to be disposed of. Most of these waste finishes are considered a hazardous waste.

-Most finishes do the opposite of what they are designed to accomplish. That is they become a dirt magnet.  I have conducted experiments that show a coated surface will attract more dirt than a surface restored using a green system.

Even today’s stone restoration companies are using polishing compounds that contain dangerous oxalic acid.

A Green stone and terrazzo restoration process have no negative impact on the building environment or the occupants since  no chemicals or finishes are used. The maintenance requirement after the stone or terrazzo is restored is reduced by as much as 50% or more saving on labor and chemicals.

 

 

Objections:

There are many professional stone restoration companies as well as others who will object to the fact that stone can be restored, polished or maintained without some chemical procedure. The following are some of these objections:

 

Stone cannot be polished without the use of chemicals?

Many stone restoration companies will argue that it is impossible to achieve a deep high reflection on natural stone without the use of chemical polishes. This in fact is not true.  Mechanical polishing using diamond abrasives alone with the proper equipment can achieve results that are as good as or superior to chemical polishes.  There are several great examples of this. Take a look at the floors at Syracuse International Airport and Chicago Ohare and you will some great examples of sustainable polish. In addition I have worked with several school systems that have their terrazzo floors polished with this method.

 

It costs more to go green?

Again this is not true. As a matter of fact going green cost a lot less. This is especially true after the stone is restored and needs to be maintained. An independent study shows that the payback is under 3 years with a saving of around $1.85 per square foot per year.

As a small Contractor I can’t afford the large machines necessary to do this work?

I will not disagree that it takes large machinery that is expensive. In fact for small residential and commercial projects these large machines will be impractical.  However, technology is advancing and there are now diamond abrasives that will achieve a polish equal to or greater than a polish achieved by chemical methods.  I am old enough to remember when there used to be small corner grocery stores all over the US. Today the large chains have put these small stores out of business. I’m afraid this is what will happen to the small contractor if they don’t keep up with current methods and seek to develop sustainable methods to compete with the larger companies.

Even with small to medium hotels etc, it is impossible to use 220 V or three phase machines since they will require a large generator that is too noisy for these facilities?

Again, I cannot agree more and this is why there are propane powered machines available. These machines are quiet and are rated by EPA and OSHA to be used indoor. I know of several contractors who are using these  machines and methods vey successfully in small to medium size buildings.

Times are changing and technology is advancing. Sustainability is fast approaching and in no time it will be required in many states.  Yale University has already put policies into place that ban the use of any chemicals for not only restoration but for  maintenance. Several states now have legislation in place that will mandate that sustainable methods be used in maintaining flooring surfaces. 

The small contractor that fails to see the future and at least be aware of these advances will be zapped back to the Stone Age and struggling like a caveman hunting for his next meal.

 

Be Wary of Green Washing                                                                                                                                                                            

Caution must be exercised when looking at what constitutes a “green” product. Many chemical companies have reduced the percentage of hazardous chemicals in their formulations. However this does not make the product any safer. Many articles have discussed this and have called it Green Washing. A great example of this is in a article by The Environmental Working Group(www.ewg.org/schoolcleaningsupplies , which  uses the cleaner Simple Green as an example.  There article states that  Simple Green claims to be non-toxic and biodegradable but fails to mention that the principal cleaning ingredient it contains is a possible human carcinogen. The hazardous ingredient is still present along with all the dangerous it exhibits.  To be totally sustainable it is best to use NO CHEMICALS at all.

Tile Bond vs Coverage

Tile Bond vs Coverage  

Frederick M. Hueston, Stone Forensics

 

Experienced installers and inspectors are aware of the requirement for coverage on stone and tile installation. ANSI requires an 80% coverage in dry areas and 95% in wet areas for ceramic tile as follows:

 

ANSI A108.4- Installation of tile for floors and countertops

               A-4.2.2.4.2 Thoroughly beat all tile or tile assemblies into place with a beating block to obtain maximum contact of adhesive on the back of each tile, or back of each tile and back mounting material, and not less than an average contact area of 80% except on shower installation where contact area shall be 95% when no less than three tiles or tile assemblies are removed for inspection.

Many local and state codes also require the same coverage.

 

Natural Stone guidelines set by The Natural Stone Institute and the Tile Council of North America require 95% coverage in all areas.

So coverage is nothing more than the amount of setting material touching the back of the tile. No where in the industries guidelines does it state a percentage of bond.

Bonding is defined as something to join two things together. In the case of tile setting it would be to join the tile to a substrate via an adhesive.

But is coverage and bonding the same.  I would argue that the two are not necessarily the same or in some cases not even related.

For example, a tile set in a sand bed would have 100% coverage but zero bond. On the other hand a quarter size dot of epoxy on the back of a tile would make it almost impossible to pull up which means it has a good bond.

As long as the proper adhesive is used a high coverage percentage can have a high bond strength, but experts need to be cautious when describing tile failures and not to confuse coverage vs bond. This is something I run across all the time where experts confuse the two terms. 

As many experts are aware there all kinds of bond failures that do not relate to coverage. Some examples are as follows:

1.      Incorrect setting mortar or adhesive. This is especially true when standard thin sets are used on resin back tiles.

2.      Bond breakers on the tile- Dust, sealers, curing compounds and other materials that can interfere with bonding often result in lack of bond

3.      Skimming over- This is when thin set mortar is applied to the substrate and it starts to cure before the tile is set.

4.      Improper mixing- Improper mixing of the setting mortar and/or adhesive can result in poor or no bond

5.      Flash setting due to hot substrate

6.      Improper beat in

7.      Failure to clean back of the tile

8.      Improper dilution of additives in the setting mortar

These are just some of the common reasons for bonding failures. Non of them can be contributed to coverage.

Failures that can be caused by poor coverage are the result of voids in the setting mortar or adhesive and can include:

1.      Cracking

2.      Hollow sounds

3.      Water intrusion in the voids of the setting mortar

These failures are related to coverage but not to bonding.

 

In conclusion one needs to be aware of the differences between bonding and coverage failures.

Graffiti Removal

Graffiti Removal Procedure for Stone, Masonry, and Tile Surfaces

By Frederick M. Hueston, www.stoneforensics.com

 

If your beautiful building, wall, or other surface has just become the unintended canvas for graffiti, your first reaction might be to call your maintenance staff to pressure wash the spray paint away. Unfortunately, pressure washing can leave stains behind or shadowing caused by the high-pressured water. If you are dealing with paint, markers, or other water-soluble types of graffiti, as well as post-cleanup stains or shadowing on stone, tile, brick, or masonry, this article offers some guidance on what to do next. 

Graffiti Types

 

There are many kinds of paints, markers, or other mediums that are used for graffiti. The most common types are aerosol paints and felt tip markers because they are easy to acquire and relatively inexpensive. Other graffiti mediums include chalk, charcoal, foods such as ketchup and mustard, red clay, and more. Any graffiti created with water-soluble material will be easy to remove with a mild washing.

Scribing is a type of graffiti that often causes permanent damage since a knife, screwdriver, rock, or other sharp object is used to scrape away the surface.

 

Graffiti Removal Rules

 

When it comes to graffiti removal, here are some very important considerations.

Time
The longer graffiti remains on a surface, the more likely it is to soak into the surface. The deeper it penetrates into the surface, the more difficult it will be to remove. For this reason, you will want to attempt removal as soon as possible.

Temperature
During summer months and in areas with warm climates, graffiti will dry faster and will have a tendency to penetrate deeper than in colder climates.

Abrasives
High pressure washing, and abrasive brushes should be avoided, especially on soft stone, brick, and masonry surfaces. These methods may remove the graffiti but could leave a deep mark or what is called shadowing which is nearly impossible to correct.

Cleaners
Be careful choosing the proper cleaners or stain removers. Certain chemicals will emulsify the paint and drive it deeper into the surface making removal even more difficult.

Removing Graffiti

 

Step 1 
Attempt to identify the graffiti type. Identification is key, since it will help you chose the proper chemical. Paint or marker are water-based or solvent-based mediums. Water-based paints can generally be removed with mild detergents, whereas solvent-based paints will require mineral spirits, paint stripper, or other solvent-based cleaning agents.  The best way to find out what type of medium you are dealing with is to test a small area as follows. Once you know the medium, proceed to Step 2.

CAUTION: Make sure to do the water-based test first, since water-based paints can give false-positive test results with the solvent-based test.

Water-Based Test
Mix some mild detergent, such as a pH-neutral cleaner or dish soap and water in a spray bottle. Saturate a small area and allow it to sit for a few minutes. Wipe it off with a soft, white cloth. You may also agitate the area with a soft nylon bristle brush. If the graffiti comes off easily, then you are dealing with a water-based paint.

Solvent-Based Test
Moisten a clean, white rag with a small amount of mineral spirits. Gently blot the graffiti. If the graffiti is easily removed, then you are dealing with a solvent-based paint. 

Step 2

1. Prepare a solution, per the manufacturer's dilution instructions, of a pH-neutral cleaner or dish soap and water in a bucket or sprayer.
2. Rinse the surface with plain, clean water. This step is important, because it removes any potentially abrasive material such as dust, dirt, or grit from the surface.
3. Apply the cleaning solution with a soft nylon scrub brush. Work from the bottom of the wall to the top. Do not let the solution dry. If necessary, work in small sections. Lightly scrub the surface with the nylon brush and rinse with clean water.
4. If the above technique does not remove the graffiti, proceed to Step 3.

Step 3

1. Make sure the surface is dry before proceeding further.
2. Put some paint stripper, such as mineral spirits, in a chemical-resistant spray bottle.
3. Apply a mist to the graffiti and scrub with a dry nylon brush. 
4. Rinse the area with paint stripper.
5. Repeat this process, working in small areas at a time, from the bottom of the wall up. Be sure to rinse any streaks as you work.
6. If the graffiti is not totally removed, this means it is a stain. To remove a stain, proceed to Step 4.

Step 4
To remove a stain, apply a poultice, that is, a paste made of an absorbent powder mixed with a chemical. As the poultice dries, it wicks or lifts the stain out of the pores in the surface. First, select the appropriate ingredients.

Poultice Ingredients
Following are some types of poultice powders to mix with your cleaning agent:

• Clays (Attapulgite, Kaolin, Fullers earth) WARNING: DO NOT USE ON RUST STAINS
•  Talc
•  Chalk (whiting) 
•  Sepiolite (hydrous magnesium silicate) 
•  Diatomaceous Earth
•  Methyl Cellulose

Clays and diatomaceous earth are usually the best. Do not use whiting or iron-type clays, such as Fullers Earth, with acidic chemicals. They will react with the material, canceling the effect of the poultice.

Many stains are so deeply imbedded that the poultice alone will not be completely effective. Some type of chemical solution will need to be added to the poultice. When the poultice and chemical are applied, the chemical is absorbed into the stone or masonry. The chemical reacts with the stain and is re-absorbed into the powder/material. 

Following are suggested poultice ingredients. Please use extra caution when handling the chemicals listed below. Thoroughly read the Safety Data Sheets for each chemical before use.

• Iron (rust) - Poultice with Iron Out + powder + water. Iron Out is available at hardware stores. This may etch polished marble. If so, re-polishing will be necessary.
•  Ink - Poultice with mineral spirits or methylene chloride + powder.
•  Oil - Poultice with ammonia + powder. Methylene chloride can also be used on tough oil stains.
•  Coffee, Tea & Food - Poultice with 20 percent hydrogen peroxide + powder.
•  Copper - Poultice with ammonium chloride + powder.
•  Water-Based Paint - Poultice with a commercial paint remover + powder.
•  Oil-Based Paint - Poultice with mineral spirits + powder. Deep stains may require methylene chloride.

 

Applying the Poultice

1. Wet the stained area with distilled water. Pre-wetting fills the pores of the stone with water, which will help isolate the stain and accelerate the removal by the chemical.
2. Prepare the poultice. Mix the powder and the chemical of choice into a thick paste, about the consistency of peanut butter or thick enough that it will not run. 
3. Apply the poultice to the stain. Apply the paste approximately 1/4-inch thick, extending beyond the stained area by about one inch. Be careful not to spill any on the surrounding area.
4. Cover the poultice with plastic (food wrap works great). Tape the plastic down to seal the edges. It also helps to poke several small holes in the plastic, so that the powder will dry out. Failure to do this may result in the poultice staying wet. The idea is to allow the moisture to slowly evaporate from the poultice.
5. Allow the poultice to dry thoroughly. This is a very important step. The drying of the poultice is what pulls the stain from the stone into the poultice material. If the poultice is not allowed to dry, the stain may not be removed. Drying usually takes from 24 to 48 hours.
6. Use a flat, plastic scraper to carefully remove the poultice from the stain. Rinse with distilled water and buff dry with a soft cloth. If the stain is not removed, reapply the poultice. It may take up to five poultice applications to remove very difficult stains.
   
   

Some chemicals may leave etch damage on honed or polished marble and limestone surfaces. If etching occurs on a polished surface, apply polishing powder and buff with a piece of burlap to restore the shine. If etching occurs on a honed surface, do not use polishing powder, because this will leave a polished area that does not match with the surrounding finish. Contact a professional stone restoration contractor to remove the etch and restore your honed finish.

Why is my Grout Turning Yellow

Why is My Client’s Grout Turning Yellow?

By Frederick M. Hueston, Stone Forensics

Over the years I have received many calls from stone and tile restoration professionals asking how to identify the cause of grout yellowing and resolve grout yellowing problems. The reasons for this discoloration are many. Testing can help determine what is causing the problem. Solutions vary, depending on the cause. Here are the details.

Top Ten Reasons for Grout Yellowing

1.      Shampoos, soaps, etc. – Many of the personal items your clients use contain chemicals that can cause discoloration, and hence yellowing of grout. This is especially true of hair dyes and shampoos that contain coloring agents.

2.      Body oils – Skin and hair oils contain many contaminants that can cause discoloration of not only grout but also tile. These body oils are what cause the familiar yellow stain, ring-around-the-collar.

3.      Sealers and waxes – Sealers and various waxes can contain polymers that can discolor over time and cause yellowing.

4.      Grout types – There are numerous grout types that are prone to yellowing. White epoxy grouts are notorious for turning yellow.

5.      Cleaning products – Certain cleaners, especially those that contain dyes, can cause discoloration of grout. Household bleach commonly discolors grout.

6.      Iron – Certain water supplies contain iron. Water containing iron can deposit minerals on the grout that can oxidize and cause a yellow discoloration. If the water used to mix the grout during installation contained iron this can also cause discoloration. Check your water supply for iron.

7.      Dirty water – Water used to mop floors can rapidly get dirty. The dirt, oils, etc. will settle on the grout lines and cause a yellow cast. Encourage your client, or the cleaning or janitorial services they use, to keep mop heads clean and change mop water often.

8.      Smoke – Cigarette smoke can settle on grout lines, causing the grout to turn yellow.

9.      Aerosol sprays – Sometimes aerosol sprays, such as hair sprays and even air fresheners, cause grout discoloration.

10.   Bleed over – Certain tile types, such as white marble, contain iron. Iron from the tile can bleed into the grout and oxidize, causing the grout to turn yellow.

How to Test for Yellowing

As mentioned above, there are many reasons why grout can turn yellow. Here are some suggestions for inspecting the grout to determine the cause:

1.      Determine what cleaning products and toiletries have been used in the area. Look up the SDS on the product to determine whether products contain dyes, polymers, or other ingredients that may cause grout to turn yellow.

2.      Test the grout lines for iron using a product from Alpha Tools called RSR 2000. Place a small dab on the grout and wait several minutes. If it turns purple, it is positive for iron.

3.      Test the water for iron if iron oxidation is suspected. Test kits can be purchased at most home centers or water supply stores. If iron is present in the water, suggest that your client install a water filtration system.

4.      Try to determine the grout type. Epoxy grout can be problematic.

5.      Take a knife and scrape the grout. Examine the scraped area to see if the discoloration is on the surface or all the way through. Surface discoloration usually indicates chemical discoloration.

Once the cause of grout yellowing is determined, you can attempt to resolve grout yellowing problems. Be sure to instruct your client about using preventative measures such as discontinuing the use of stain-causing products, smoking outside, installing a water filtration system, etc.

How to Clean Yellowed Grout

To clean yellowed grout, you will need sulfamic acid, which can be purchased at most home centers and can also be found at most tile supply companies, and a good floor wax stripper, which can be purchased at most janitorial supply houses. Ask for an alkaline-based floor wax stripper. Caution: Sulfamic acid will damage marble surfaces.

Here are cleaning instructions:

1. Sweep the floor thoroughly, removing any loose dirt, dust, etc. For showers and walls, wipe with a dry rag.

2. In a cleaning pail, mix warm water and a good floor cleaner or ammonia. For showers and walls, use a clean rag and for floors, use a clean mop to clean the grout. Empty the pail.

3. Next, mix alkaline stripper with warm water, being sure to follow the directions on the bottle.

4. Apply a small amount of this solution to the grout. Allow it to stand for several minutes. Agitate the solution with a scrub brush, toothbrush, or similar type brush. Apply additional solution if the grout begins to dry.

5. Pick up any excess solution with a mop or a wet vacuum.

6. Rinse the grout with plain, warm water. Empty the pail.

7. Mix sulfamic acid with warm water, per the directions on the label.

8. Apply the acid solution to the grout and agitate.

9. Rinse the grout several times with clean water and allow to dry overnight.

10. Once dry, seal the grout with a good penetrating sealer.

If the above technique does not work and the grout is in good condition and not falling apart, then apply a high-quality grout color sealer. As a last resort, remove and replace the grout.

How Setting Mortars Bond

How Setting Materials bond and Why Resin Back Tiles Fail

Frederick M. Hueston, Stoneforensics.com

If you search the internet and try to find an explanation of how thin sets and other setting materials form a bond to a tile you will not find much. The manufacturers will give you a slew of marketing jibber jabber siting bonding agents as well their secrete formulas. The following article will break down the basics of thin set and other setting materials chemistry. With this information you can begin to understand why some setting materials do not bond properly or at all.

In order to understand the basics, we must first look at what thin sets and setting material are made of. The main component is Portland cement. Of course, there are other ingredients such as bonding agents but in the largest component is Portland Cement.  So all one needs is a basic understanding of how Portland cement cures to understand how these setting material can bond to tile.

Understanding how Portland Cement Cures

Portland Cement is a combination of aggregate and a cement mixture made from limestone, shells, and chalk or marl combined with shale, clay, slate, blast furnace slag, silica sand, and iron ore. Limestone is heated at high temperatures to form a solid material. This solid is than ground to form a fine powder that we call cement.

Cement is not Concrete

In order to form concrete that we are familiar with an aggregate need to be mixed with cement. The cement and aggregate are added together and mixed.  This is typical how you buy a bag of concrete. The bag you purchase at your local home center or building supply is a combination of dry cement and an aggregate. When you add water to this mix a reaction occurs that causes the concrete to harden(cure).

How Concrete Cures

When water is added to the concrete mix a reaction starts to take place called hydration. In other words the cement paste reacts with the water forming microscope crystals and branches(see photo #1). Without water the hydration process cannot happen, and the concrete will not cure.

How Setting Materials form a bond

Now, keep in mind that tile setting materials are basically concrete. In order to form a bond to the back of the tile there has to be moisture exchange. In other words, the back of the tile must be absorbent. As the concrete cures these little crystals and branches enter the pores of the tile and help create a bond. This bond can be compromised by numerous factors.

Lack of Bond

If the tile is nonabsorbent it will not bond since the crystals and branches cannot grab the tile. This is why resin backed tiles will not bond properly. The resin forms a nonabsorbent coating on the back of the tile.

Bonding Agents Play a Role

Bonding agents such as acrylics, latex etc are added to many setting materials to create a strong bond, However in most cases the back of the tile will still need to have some absorbency. This is why most thin sets and setting materials will have limitations listed on them. In many cases manufacturers recommend using an epoxy setting material on resin back tile. Epoxy setting material create a chemical bond and do not require absorbency of the tile.

Figure 1- Concrete hydration forming crystals and branches

Why Do My Tiles Sound Hollow?

Why Do My Tiles Sound Hollow?

By Frederick M. Hueston, Stone Forensics

Ask any stone or tile inspector what is the number one test they use to determine if a tile is bonding and most will say the sounding test. For those not familiar with sounding, the test is simple. A hammer, chain, golf ball, chisel, or any other hard apparatus is used to tap the tile. If the tile sounds solid, it will produce a pinging sound. If it is not bonded or there is a void in the setting mortar, the tile will sound hollow and produce a thud-type sound. The sounding test is a very worthwhile test. However, with that said, it needs to be performed by a qualified expert who has a good ear for sounding, since the sounding test can give erroneous results and can lead to incorrect conclusions. A sounding test should always be followed by a destructive test to verify the results of your sounding. A definitive conclusion should never be made based only on the results of sounding.

Here are some of the reasons that a marble or other natural stone tile can sound hollow and detached when in fact it is not:

·                MEMBRANES. Many installations today use a soundproofing, crack-isolation membrane and other membranes. This is especially true for slab on grade installations. Sounding over these membranes can produce a different sound than the same tile or stone installed without one. The sound is difficult to describe, but it sounds muffled. The overall sound should be consistent. If not, a destructive test should be conducted in those areas where the sound varies.

·                VOIDS IN STONE. If you are sounding stone, you must have a good understanding of the type of stone and its characteristics. Many stones, especially limestone, will contain natural voids within the stone. These voids can produce a different sound and may be mistaken for improper installation. The only way to verify this is a destructive test.

·                ACOUSTICS (Low Ceilings). You must pay attention to what is above the floor you are sounding. If you are sounding a floor and the sound suddenly changes, look up and see if you have moved under a low ceiling or if the ceiling changes in any way. Metal ceilings will sound different than acoustical tile or other ceiling types.

·                TRAPPED AIR. Trapped air in the setting bed or substrate can result in false hollow sounds.

·                SAND BED INSTALLATION. Many patio and pool deck pavers are set in compacted sand. The tiles are not bonded, and the entire installation will sound hollow.

·                GROUT JOINTS. Believe it or not, the width of the grout joint and how it is placed can cause the tile to sound hollow. This is especially true if the grout is not pressed deeply in the joint.

·                FOAM SHOWER PANS. Foam shower pans are now being installed and will produce a hollow sound.

Sounding Test Tips

1.                  Always use the same device on an installation. My favorite is a golf ball, but a hammer, broom handle, metal pole, etc. can also be used. Be careful with handles that are hollow since you may be hearing the sound of the handle rather than the floor.

2.                  Be sure to tap the tile in several locations. I like tapping a tile in a grid pattern across the tile and making sure to tap the corners.

3.                  Listen for a consistent sound. If the entire tile installation sounds hollow, it could be the substrate and not a failed installation.

4.                  A flood does not cause hollow tiles. See my article on flooding to find out why.

5.                  Getting training to make sure you are preforming the proper technique.

There are numerous reasons a tile can sound hollow, and it does not necessarily mean the installation will fail. The best way to remove all doubt and determine if there is a bonding problem is to examine the setting bed, bonding, coverage, etc., which requires a destructive test.