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.

Efflorescence - Removal and Prevention

Efflorescence - Removal and Prevention

By Frederick M. Hueston, stoneforensics.com

The following article discusses historic masonry but the causes and principles are the same for any stone, brick or concrete surface.

The crystallization of soluble salts in Historic masonry causes severe deterioration of the substrate. This crystallization is called subflorescence. These salts are derived from several sources, including salts within the substrate, pollution, deicing salts and improper cleaning chemicals.  Problems associated with subflorescence can be diagnosed and identified by visual clues, such as spalling and rising damp.  Accurate diagnosis of subflorescence can be confirmed with laboratory testing. Once the salts are detected there are several methods which can remove these salts. Water washing, surface rendering and poulticing are a few of the methods used.  If these salts are successfully removed it is important to prevent reoccurrence. Preventative applications might include installation of dampproof barriers, chemical injection and coating the masonry with a sealer or impregnator.

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Subflorescence

 The deposit of water soluble salts in the pores of Historic masonry is the major cause for deterioration of these surfaces.  These salts originate from several sources.   Gauri, Holdren and Vaughan (1986) report that these salts are inherent in brick, concrete and natural stone.  Boyer(1986) contributes polluted rain water, roof salts, deicing salts and adjacent materials as the source of salt deposition.  Ashurst(1994) reports that careless cleaning using improper chemicals can deposit salts causing deterioration.   Regardless of the source all agree that water soluble salt deposition contributes significantly to the rapid deterioration of historic masonry.

Grimmer (1984) defines Subflorescence as follows:

Subflorescence is a potentially harmful accumulation, or build-up of soluble salts deposited under or just beneath the masonry surface as moisture in the wall evaporates.  Particularly during the freeze-thaw cycle, the moisture and salts in the wall freeze and expand, building up pressure within the masonry, which if sufficient, may cause parts of the outer surface to spall off or delaminate. (P. 22)

In other words, Subflorescence is the deposit of salt crystals beneath the surface of the masonry.

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Subflorescence and Efflorescence

Subflorescence should not be confused with efflorescence.  Efflorescence is a deposit of soluble salts on the surface of masonry. Efflorescence can be identified by a whitish haze on the surface of the masonry.  Efflorescence can be a precursor to subflorescence since its  indicates the presents of salts.  Efflorescence is common and often harmless on newly constructed buildings, but if it appears on historic masonry, it should serve as a warning that moisture has found a way into the masonry.

Diagnosing and Identifying Subflorescence

Subflorescence should be suspect when the following conditions are observed on a masonry surface:

1.  Spalling- Spalling of masonry surfaces can be identified by the breaking off of the surface layer. Small pieces of the outer layer will flake off in both small and large portions. Often the surface is very brittle and can easily be removed by prying with a knife. Spalling can also be called delamination when referring to manmade masonry.  The term delamination is general used for stone masonry.

2.  Rising Damp- Along the base of most masonry buildings, a wet, darken outline can be detected. This darkened area usually extends from the ground to several feet above the ground.  This darken is the result of water being carried through capillary action into the porous masonry. This condition is known as rising damp.  Rising damp can lead to efflorescence and ultimately subflorescence since salts can be dissolved and carried by the water.  Rising damp is a concern in Northern climates where deicing salts are used.  If the moisture remains during freezing months, the water will freeze, expand and cause spalling of the masonry surface.

3.  Post Cleaning Operations- Frequently masonry surfaces will develop efflorescence within several days after cleaning. The masonry surface should be checked carefully, since efflorescence can be a precursor to subflorescence.  This is especially troublesome if the cleaning operation used copious amounts of water.  Excessive use of water can saturate the masonry, dissolved salts within the masonr, causing spalling.

4. Chemical Cleaning Operations- Certain chemicals can deposit soluble salts within the pores of the masonry if not rinsed throughly.  Alkaline cleaning chemicals contain alkaline salts which can crystallize causing spalling of the masonry surface.  If spalling occurs shortly after cleaning check the type of cleaners used.

Testing for Soluble Salts

If soluble salts are suspected, a simple field test can be used to determine if salts are present. To determine the type of salts, thus leading to a possible source, laboratory tests must be conducted. The following describes these tests.

Field Testing- London (1988) describes a simple qualitative test for determining the presents of soluble salts using a protimeter.  The test uses the principle that dissolved salts have a higher capacity to conduct an electrical current.  A filter paper is saturated with distilled water, placed on a rubber block and a reading taken with the protimeter.  A second filter paper is saturated with distilled water, placed on the suspect masonry and a reading taken.  If the reading on the masonry is higher than the reading on the control, then soluble salts may be present. This test does have a margin of error and can be misleading. It is advised to verify with laboratory testing.

Laboratory Testing- Laboratory testing can determine quantitative as well as the exact identification of the salts.  It is important to know which type of salts are present in order to determine the origin.  Most all salts in historic masonry can be classified as follows:

Chlorides- Chloride salts are found in deicing salts. Ashurst (1988) also reports that chlorides can be hygroscopic, taking moisture directly from the atmosphere. Chlorides can also be found in high concentrations in environments near oceans and salt marshes. Chlorides can also be present in the make up of the masonry itself.

Nitrates- If nitrate salts are detected, ground water should be suspected. Nitrates are commonly found in fertilizers and in soils.

Carbonates- Carbonates are found in high concentrations in masonry mortars continuing lime. Carbonates are also present in pointing mortar and will usually present a problem when a building is repointed.

Sulfates- Sulfates are found in air pollution from vehicle exhaust, industrial pollutants etc. Sulfates are an increasing problem in areas where pollution is high.

Alkaline and Acid Salts- Alkaline and acid salts are deposited into historic masonry when cleaners are used and not rinsed probably. If efflorescence and/or subflorescence occurs shortly after cleaning, these salts should be suspect.  Hydrofluoric acid is commonly used to clean historic masonry since it is one of the few chemicals that do not deposit soluble salts(Ashurst, 1988).

Subflorescence

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Removal of Soluble Salts

Before any attempt is made to treat historic masonry and to remove both efflorescence and/or subflorescence it is necessary to find the origin of the salts. If this is not found, further damage may result.  Once the origin is found the first step in salt removal is to eliminate the source.

There are several methods for desalination of historic masonry. The following methods have proved successful but are not fool proof. It is vital that these procedures be performed by trained and experienced individuals.

Ashurst (1988) describes two possible procedures for removal of soluble salts, poulticing and sacrificial rendering.  Poulticing uses an absorbent clay mixed with distilled water into a paste.  This past is applied to the masonry, which has been saturated with water. As the clay dries it will absorb the moisture from the masonry carrying the salts with it.  Poulticing can be an effective treatment for removing soluble salts but caution must be exercised since salts can be drawn to the surface and crystallization may occur. Sacrificial Rendering uses an application of a thin coat of a lime and sand mixture.  This mixture is trowel on the wall as if applying stucco. The principle is that the rendering will absorb moisture and transfer the soluble salts to it.  Gauri et al (1986) describes two suction techniques for removal of soluble salts.  The suction method uses a vacuum pump attached to a funnel. The masonry is saturated with water and the vacuum pump pulls the moisture out with the soluble salts.  This method can be time consuming on larger surfaces but industrial equipment is available that can process several hundred square feet per day. Grimmer (1984) suggests the use of water washing to remove efflorescence.   The water washing method employs the use of water sprayed on the surface of the masonry. The water can be applied with

high pressure, low pressure, intermittent with an endless number of spray patterns. Water washing is the most common method employed for cleaning historic masonry but does have its shortcomings. Chemical cleaning is often used in an attempt to remove soluble salts with little to no result. Hydrofluoric acid is the most often used chemical on masonry surfaces.  The acid works by dissolving the salts which are rinsed away after a timed dwell period. Hydrofluoric acid also is damaging to the masonry itself since it dissolved the substrate.

Which ever method is used it is important to perform a test on the masonry and monitor it closely for any harmful effects.

Preventing Subflorescence

Damaging salts are carried into historic masonry by moisture. To prevent salt deposition it is necessary to eliminate the moisture. Grimmer (1984) suggests using a dampproof course. This dampproof course consists of placing a material such as plastic, horizontally in a masonry wall to prevent moisture from rising into the substrate.  Injecting chemical plastics into the masonry have also been used to eliminate moisture as well as the application of sealers and impregnators. 

Whichever preventive treatment is used it is important to remove the existing salts. This can be accomplished by the methods mentioned above or the masonry should be left alone and the salts allowed to migrate out. This is especially important with chemicals treatments. Sealers,

consolidants and impregnators should not be applied to masonry containing salts.  The application of these sealers, etc will prevent moisture from escaping, accelerating the chance of deterioration.

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Conclusions

The deterioration of Historic masonry through the crystallization of soluble salts is a growing problem in the preservation community. Improper cleaning techniques and air pollution both contribute to the build up of these salts.  It is important that the proper diagnosis be formulated so that further damage is not caused.  Desalination practices and procedure must be tested and performed by experience individuals.

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References

Ashurst, J.   (1988).     Practical Building Conservation.   New York: Halsted Press.

Ashurst, N.   (1994).    Cleaning Historic Buildings Volume I.   London: Donhead.

Boyer, D.W.   (1986).   Masonry Cleaning-The State of the Art.   American Society for Testing     and Materials.   25-51.

Gauri, K.L.   (1986).   Cleaning Efflorescence from Masonry.      American Society for Testing      and Materials.   3-13.

Grimmer, A.   (1984).    A Glossary of Historic Masonry Deterioration Problems and Preservation     Treatments.   Washington: Department of Interior.

London, M.   (1988).   How to Care for Old and Historic Brick and Stone.   Washington:     Preservation Press.

What’s Under Your Carpeting

What’s Under Your Carpeting

By Frederick M. Hueston. Stoneforensics.com

If your building was built prior to 1980  chances are you are hiding one of the most beautiful, elegant and sustainable floor materials. That material is known as Terrazzo.  Today, sustainability or what is more commonly known as Going Green is rapidly being required by many school systems, governments and private industry. Of all the materials  that can be used for flooring there are only a few that qualify as sustainable and are considered safe. They are stone and terrazzo.  However, even these materials can contribute to pollution and pose all kinds of health and safety risks if not properly cared for.

Why should you be concerned about your carpets and other flooring?  The General accounting office of the EPA reports that one of the top five health concerns is Indoor Air Quality. In addition they report that nearly 50% of the US schools have this problem.   

The following article will outline some of the hazards associated with other floor materials such as carpet and vinyl, as well as present a truly sustainable restoration and maintenance process for stone and terrazzo flooring. This information should help with your quest to improve indoor air quality in your school or building.

Carpet

Of the entire floor covering available carpet is the most popular and also the most hazardous. New and Old carpet alike emit harmful VOC’s (volatile organic Compounds) into the air. Solvents such as toluene, benzene, formaldehyde, ethyl benzene, styrene, acetone and the list goes on and on.  Carpets are also a great breeding ground for dust mites, fleas and other insects as well as toxic molds and mildew.  In addition carpet cleaning chemicals have been linked to diseases such as Kawasaki’s, fibromyologia and allergies.

Carpet in schools, offices and other public and private buildings are even more hazardous due to the number of people who not only walk on them but also people deposit skin cells, dust etc, not to mention food and drink that is spilled on them which provides the organic material necessary for bacteria to grow and thrive.

Of all the floor coverings carpet has the shortage service life.

Vinyl Composition Tile(VCT)

VCT is just as hazardous as carpet and possibly even more. The Adhesives used to attach VCT emit high levels of VOC’s. Since VCT is a tile moisture is often found between the tiles where toxic mold can grow.

VCT is found in almost all schools, government buildings etc. VCT is very inexpensive. VCT is made ( insert what it is made of here)

In addition to VCT composition almost all of it is maintained with harmful acrylic coatings. These coating need to be removed(stripped) and the strippers used contain hazardous chemicals as well(see article titled(Are Floor Strippers Safe). The Environmental Protection Agency(EPA) recommends that any major maintenance be performed only when the school is unoccupied for 48 hours.

Agglomerates

Agglomerated tile is composed of real stone fragments and polyester or epoxy resins. Some name brands include Fritz tile, Rover, Etc.  The manufacturing process uses synthetic resins that emit high amounts of VOC’s

Agglomerates are often maintained using the same hazardous coatings and strippers used on VCT

Terrazzo and Stone

Marble, Granite, limestone, slate and terrazzo are the only true sustainable floor coverings. Stone is all natural and contains no harmful VOC’s or any other hazardous elements. They are manufactured by mother earth and there fabrication uses only water and abrasives.  Terrazzo is composed of natural stone and Portland cement and is also very sustainable. In addition Natural Stone and Terrazzo flooring is long lasting. Just look at some of the buildings in Italy, France and other countries around the world. Some of these stone floors are hundreds of years old.

The dangers with stone and terrazzo floors come with the restoration and maintenance of these surfaces. Hazardous chemicals, polishes, sealers etc are often used for restoration and maintenance.  These chemicals are as hazardous as the waxes and strippers used on VCT and agglomerated floor coverings.

The good news is that Stone and Terrazzo flooring can be restored and maintained with no harmful or hazardous chemicals.  The restoration process uses only water and abrasives. Daily maintenance can be carried out using only Green Seal approved neutral cleaners.

If your floors are currently covered with carpet, vinyl etc.you may want to consider removing these harmful and dangerous floor coverings and restoring the terrazzo or stone that is under them.

Note: If you floors are not stone or terrazzo and are only concrete. Concrete can be polished and maintained as well.

The Stone Restoration Horizon is Changing. Are You Ready?

The Stone Restoration Horizon is Changing. Are You Ready?

By Frederick M. Hueston

Does old ever become new again? In the case of how stone restoration is done, the answer very well could be yes. I am referring to the polishing system for stone flooring that was used many years before chemicals came into existence, which is once again becoming the preferred method specified by more and more architects and others.  Why is this? Think “Green”. ‘Going green’ is rapidly becoming more and more prevalent everywhere and our industry is not excluded. I am finding that many projects across the US are now being specified with strict specifications that a green and sustainable restoration process be implemented for restoring both natural stone and terrazzo surfaces.  

What is Green?

There is an old Indian proverb that says something like, “We are not inheriting the earth from our forefathers. We are borrowing it from our children.”

As we hear more and more about the toll pollution takes on our environment, most of us are feeling some responsibility to do our part in saving our planet, not only for our present generation but for generations to follow. Everywhere you look, individuals, government agencies, universities and schools, and even private businesses are going green.

What Exactly Does Going Green Mean?

The term ‘green’ or ‘going green’ is a term we hear frequently these days, but few really know what the term means. Going green can be aptly defined as 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 as well as individuals feel that they are too insignificant to make any impact on the environment. If this is the way you think, consider the following:

·       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.

Can Stone Restoration Go Green?

Traditionally the restoration, repair and maintenance of stone and terrazzo surfaces are anything but ‘green’. We use chemicals that are harmful to the environment and to people in general. Chemicals such as polishing compounds contain 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 copious amount of waste and use large amounts of fresh water. Can such a non-green process be completely transformed into a green one?

The answer is a resounding yes. I am currently working in a cooperative effort with several stone restoration companies that are on the leading edge in ‘going green.’ They are actively and continually developing methods to eliminate all of these harmful chemicals and processes from their services. 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 that comes off and gets left behind on the floor. The diamond abrasive is fixed to a pad. There are no chemicals used at all.

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

Superfine abrasives are then used to polish the stone or terrazzo. These abrasives contain no harmful chemicals.

This green stone and terrazzo restoration process has no negative impact on the building environment or the occupants since no chemicals or topical finishes are used. The maintenance requirement after the stone or terrazzo is restored is reduced by as much as 50% or more thus reducing additional costs on labor and chemicals.

In addition to traditional diamond abrasives there are companies such as Innovative Surfaces Solutions(http://www.innovativesurfacesolutions.com/) that manufacture pads that are chemical free and achieve the same results.

The Advantages of a Chemical-less Process Go Beyond Going Green

Many stone restoration and janitorial companies use chemical topical finishes to achieve a high luster on stone or terrazzo floors. Not only do these finishes contain chemicals that are harmful to the environment, they also have a negative impact on the aesthetics of the surface. 

Most finishes used on stone and terrazzo are soft and tend to show wear and scuff marks in a very short time. This increases 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 that 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 personally conducted experiments that prove that a coated surface will attract more dirt than a surface restored using chemical topical coatings.

OBJECTIONS

There are many professional stone restoration companies and others who will object to the viability that stone can be restored, polished or maintained without some chemical procedure. So what are the objections?

Stone Cannot Be Polished Without the Use of Chemicals.

Many stone restoration companies will argue that it is impossible to achieve a deep clarity and high reflection on natural stone without the use of chemical polishes.

This is simply 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. Syracuse International Airport and Chicago OHare are two great examples of sustainable polish. I have worked with several school systems that have their terrazzo floors polished with this method very successfully.

It Costs More To Go Green.

Again this is not true. As a matter of fact going green may cost a lot less. This is especially true after the stone is restored and needs to be maintained. An independent study shows that the return on investment is realized in under 3 years with a savings 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.

This is a valid argument I’m afraid. It does take large machinery that is in fact expensive. Furthermore, for small residential and commercial projects these large machines will be impractical. However, with that said, be aware that 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 with this. But, there are propane powered machines available that are quiet and are rated by EPA and OSHA for use indoors. I know of several contractors who are using these machines and methods very successfully in small to medium size buildings.

A Word of Caution: Be Wary of Green Washing                                                                                                                                       

Be leery when looking at a “green” product claim. Many chemical companies have reduced the percentage of hazardous chemicals in their formulations and call it ‘green.’ 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 an article by The Environmental Working  Group (www.ewg.org/schoolcleaningsupplies), which uses the cleaner Simple Green as an example. The 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 dangers it exhibits. To be totally sustainable it is best to use NO CHEMICALS at all.

In Conclusion…

Times are changing and technology is advancing. Higher demand for 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 be prepared for the future just may find themselves zapped back to the stone age and struggling like a caveman hunting for his next job.

What Can You Do?

Be on the lookout for stone restoration training programs to include ‘going green’ processes. The Stone and Tile School (www.thestoneandtileschool.com) is now incorporating an introduction to ‘going green’ in its stone restoration training and will be announcing courses on this soon. 

Fred Hueston, , is the Director of Stone Forensics (www.stoneforensics.com); Chief Technical Director for Stone and Tile PROS, Inc. (www.stoneandtilepros.com), and is an instructor for The Stone and Tile School where he teaches advanced courses.