Stone and Tile Blog

Thursday, July 16, 2020

MOISTURE-STONE ENEMY NUMBER ONE

MOISTURE-STONE ENEMY NUMBER ONE

Most of the problems associated with stone tile installation can be traced to moisture or water intrusion of some kind. Many stains are caused by the presents of water. Water is an essential ingredient for the setting cleaning and restoration of stone but it can also be its number one enemy.

What problems are associated with moisture and water. The following is a brief description of the problems, there prevention and remedies:

Efflorescence

Efflorescence appears as a white powdery residue on the surface of the stone. It is a common condition on new stone installations or when the stone is exposed to a large quantity of water, such as flooding. This powder is a mineral salt from the setting bed. To remove efflorescence do not use water, buff the stone with a clean polishing pad or #0000 steel wool pad. The stone will continue to effloresce until it is completely dry. This drying process can take several days to as long as one year.

Subflorescene

Subflorescene is what happens when the mineral salts migrate and do not make it all the way to the surface. In the efflorescence condition above, the slats are deposited on the surface of the stone. In subflorescene the salts crystallize just below the surface, causing stress within the pores of the stone. The result is a condition known as spalling which appears as pits in the surface of the stone. subflorescence is very common on green marbles and is very common on almost all stone surfaces where de-icing salts are used.

Iron Staining

Many light colored stone contain naturally occurring deposits of iron. Iron is a mineral found in stone and can occur randomly throughout the stone. If iron is present, it will begin to oxidize when exposed to water or other oxidizers such as acids and household bleach. Stone can remain for years without yellowing then over time may slowly turn yellow and in severe causes may turn completely brown. This oxidation process is accelerated when the stone is saturated with water. This process of oxidation is similar to the rusting of metal. If you expose a brand new nail to water and air it will turn brown and rust. The same process is occurring with the iron in the stone. If water and/ or air is eliminated the iron will not oxidize. This is the reason certain white marble suddenly turn yellow. The process is difficult to reverse and replacement of the stone may be necessary. The following stain removal technique has proved successful in several cases. Before testing this procedure it is important to first determine if iron is the cause.

Testing for Iron:

1. Before assuming the marble is yellowed due to iron be sure to attempt cleaning and stripping with a good alkaline based stripper. If these procedures fail then testing for iron will be necessary.

2. If a flood has occurred or excessive water was used first check the water for iron. There are several inexpensive test kits available that can be used to check the iron content in water. Check with your local plumbing supply store or store carrying water softening supplies. If any amount of iron is detected then it is possible iron has entered the stone through the water supply. To eliminate the iron there are chelating chemicals that can be added to the water to prevent the iron from staining. This is very important if the stone is cleaned with this water.

3. If the water contains no iron and even if it does the stone should be checked for iron content. Remove a small sample of the stone and contact a testing lab and have them analyzed it for total iron. If there are spare tiles that have never been installed also have them tested for total iron. If iron is present naturally in this stone, it will probably be detected in the spare tile. If the results return with iron present then the following procedure should be tested.

4. Check the stone for moisture. A moisture meter is a useful instrument that can be employed to check the stone for moisture. If the stone contains water, it is very possible that iron is beginning to oxidize.

Removing Iron Staining:

1. Prepare a solution of water and the following chemical: Sodium Hydro sulfite and Sodium Metabisulfite. These chemicals are available in a product called Iron-Out(TM) from your plumbing supply or home center. Mix a solution in water and apply to the effected area. Allow solution to soak in and keep wet for several hours. Do not allow solution to dry. After several hours pick up excess solution with a wet vacuum and rinse throughly with water and a chelating agent such as EDTA. Be prepared to repolish any marble since these chemicals can cause etching.

2. If the above procedure fails than prepare a poultice with diatomaceous earth and the Iron Out(TM). Mix the poultice into a thick paste and apply to a small area. Cover the poultice with plastic and allow it to sit covered for 24 hours. After 24 hours remove the poultice paste and rinse the area with water and a chelating agent. If the stain is removed, the entire surface can be treated. If the stain still remains then replacement is the only solution.

Before the above procedure can be performed, it is important that the effected area be dry. If water or moisture are still present, oxidation of iron may continue

The yellowing of stone is a common problem. New installations should be sealed with a good quality penetrating sealer(impregnator) Which will help prevent oxidation of the iron by eliminating moisture.

The above procedure has proven successful in some cases of iron staining however if the following test does not produce the desired results I would recommend replacement of the effected areas.

Warping

several type of thin stone tiles are very susceptible to warping. Many of the green marbles and a few agglomerate marbles are notorious for this warping condition. Many of an installer have had the surprise to find that there tile installation has become warped overnight. Why does this a happen and can it be prevented. Warping is caused by water. Green marble set with any water based material will have a tendency to warp. The mechanism of why the tile warps is somewhat a mystery. Some believe that the water fills the pores of the stone and when the water evaporates the orientation of the stones crystal change and cause it to warp. Whatever the reason, one thing is for sure, green marble can warp when set with water based materials.

Cure: Once a green marble tile warps it is difficult to repair. Attempts have been made to grind the tile flat , but this usually fails since additional water is introduced during the grinding process. The green simply warps again.

Prevention; The only way to prevent warping is to install it properly with a non-water based material such as epoxy. Some installers have also ben successful in sealing the back of the tile with epoxy and installing it in a water based system(see July Stone & tile Report). Do not attempt to seal the back of the tile with a silicone sealer. The silicone acts as a water repellant and will cause the setting material to fail resulting in a bond loss.

Erosion

Erosion is a condition found when stone is exposed to constant amounts of water. This is especially true with marble that is used in water fountains. While marble is a very decorative material, it is one of the worst materials to use in or around water. Marble is composed of calcium carbonate. Calcium carbonate is a water soluble mineral. Quite simply this means it will dissolve in water. Want proof, visit the Grand Canyon. Erosion can be recognized by a slow deterioration of the stone surface. With polished stone the polish will be worn off. In older installations, the stone may become very soft, brittle and in extreme conditions, it will powder.

If any architects or designers are reading this article I beg you no to use marble for water fountains. If you do, plan on very high maintenance costs and plan on replacement in about five to ten years if not sooner.

Stabilizing erosion:

If your faced with trying to stabilize a marble fountain that is already deteriorated there are some treatment that can be applied that will extend the life of the marble. These treatments are general called consolidants and serve to replace the natural binders that are lost through erosion. Consolidants can be tricky and quite often will cause discoloration of the surface. Be sure to test the consolidant carefully before use.

Mineral crusts or Lime Putty

Mineral crusts or lime putty can be recognized by its white crust like formation on stone surfaces. These crusts are often found on outdoor stone stair, water fountains and other areas where stone is exposed to water. The crusts are a deposit of hard mineral salts consisting of calcium, magnesium. These minerals ordinate form the soil, setting bed or from the water itself. These salts are similar to efflorescence in that they are a mineral. They differ in that they form a hard crust that can be difficult to remove.

Crust Removal

there are only two ways to remove these mineral crusts. Abrasion or chemical. The mineral salts should be remove with an abrasive. I have found that a stiff non-ferrous wire brush can work well. Brushes can also be purchased that attach to an electric drill. Be careful and do not get to aggressive. Avoid damaging the stone surface.

Quite often abrasion alone will not remove all salt deposited. Strong Acidic chemicals will be required. These chemicals can be purchased from most chemical companies that supply stone cleaning products. Be careful when using these products around calcium based stone since the acid can also damage the stone itself.

Prevention.

The best prevention from mineral salts is to prevent moisture form entering the stone. On steps and fountains make sure all grout joints are caulked with a water proof material. When installing steps outdoors make sure a water proofing barrier is used. It is also a good idea to use a good stone impregnator on all surfaces to prevent water from entering the stone. Caution; Stone inpregnators will not waterproof stone. Do Not use them where hydrostatic pressure is a concern.

TESTING FOR MOISTURE

To properly test for moisture a protimeter is necessary. A protimeter is an instrument that reads moisture. The common protimeter has been designed for use with wood, drywall and other similar substances. The protimeter contains two sharp probes that are inserted into the wood or drywall to give a direct moisture reading in percent. Unfortunilty you can not push these probes into the stone, but the protimeter can give you important data oon stone moisture. By placing the pins so that the just touch the stone a relative reading can be obtained. For example, A reading of 0-6% is considerely relativly dry. A reading between 7-20% is wet. A reading of of 20% is very wet. These readings only tell you that the stone is wet, a little wet or dry. A direct percent reading can not be obtain with these instruments, but can provide useful information.

Another simple technique for determining moisture in stone is to take a piece of plastic about 12 inches square and place it on the suspected stone. Tape all four edges and allow it to stay overnight or 12 hours. After 12 hours, if there is any moisture present , you will see condensation collecting under the plastic.

TESTING FOR SALT

A protimeter can also be used to check for the presents of soluble salts. The following procedure will only tell you that salts are present. It will not tell you how much or what type. But in many cases the simple presents of salts can indicate potential spalling and/or pitting.

For this test you will need the following materials:

A rubber block

filter paper

distilled water

a protimeter

forceps

Any type of rubber will do as long as it is clean and does not contain any salts. A piece of hard plastic can also be used. Filter paper can be purchased from a scientific supply store and sometimes from the supplier who sells protimeters. Distilled water can be purchased from the grocery store.

The forceps are used to pick up the filter paper.

To check for soluble salts pick up a filter paper with the forceps. DO NOT touch the filter paper with your fingers. The human skin contains soluble salts which could be transferred to the paper giving a false reading. Place the filter paper on the rubber block. Add a drop of two of distilled water to the filter paper. Place the probes of the protimeter to the filter paper and record the reading. Next, take a new filter paper and place it on the stone to be tested. Add several drops of distilled water and take a reading. Record the reading on a piece of paper.

If the reading obtained on the filter paper from the stone is higher, then there are slats present. If it is the same or lower, salts are absent. The protimeter works by reading ionic changes. When salts are dissolved in water, the ionic changes are higher, which gives a higher reading.

www.stoneforensics.com

GROUT CLEANING, REPAIR COLORING AND MAINTENANCE

GROUT CLEANING, REPAIR COLORING AND MAINTENANCE

By Frederick M. Hueston

O, that awful dirty grout. You’ve tried everything and it just refuses to come clean. Well help is right here. Most grout becomes soiled by grease and water based stains. In order to remove the dirt it needs to be cleaned with two different cleaners. One will remove the grease and oil and the other will remove the water-based soil.

The following is my secret recipe for cleaning grout.

You will need two chemicals. Sulfamic acid and a good wax floor stripper. Sulfamic acid can be purchased at most home centers and can also be found at most tile supply companies. The floor wax stripper can be purchased at most janitorial supply houses. Ask for an alkaline-based floor wax stripper.

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

2. Mop the floor with warm water and a good floor cleaner. Ammonia will work also.

For showers and walls use a clean rag with the above chemical.

3. Mix a solution of the alkaline stripper in a pail of warm water. Make 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 and agitate with a scrub brush, toothbrush or similar type brush.

Apply additional solution if it begins to dry.

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

6. Rinse the grout with plain warm water.

7. Mix a solution of sulfamic acid with warm water per 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 then the grout will have to be removed and replaced or if the grout is sound and not falling apart, it can be re-colored.

Caution: Sulfamic acid will damage marble surfaces.

GROUT REMOVAL & REPLACEMENT

Removing and replacing grout is not that difficult. All it requires is a little patience and the know-how. The following is the know how, you supply the patience and Oh yes, the elbow grease.

You will need the following tools:

-A hand held gout saw. You can purchase these at most home centers, hardware stores or tile supply houses. They usually run a couple of dollars.

-A grout float. Also only a few dollars. I prefer the type with the rubber face, but any grout float will work.

GROUT REMOVAL PROCEDURE

1. Remove the grout using the grout saw. Work the saw in a back and forth motion until you have removed more than half the grout. It is not necessary to remove all the grout. As long as you remove about 1/4 inch minimum.

2. Once the desired amount of grout is removed. Vacuum all the grout and dust from the floor or wall.

3. Check for loose tile and re-set these before regrouting. You are now ready to re-grout.

GROUT REPLACEMENT

1. Choose the proper grout. For walls and grout joints 1/8 of an inch or smaller use un-sanded grout. For floors and grout joints over 1/8 of an inch use a sanded grout.

Caution: If you have marble tile, unsanded grout can scratch.

2. Place the grout in a bucket, add water and mix into a thick, smooth consistency. Do not mix it too soupy. Add more dry grout powder if it gets too soupy. Some grout needs to sit several minutes before using and then remixed. Check with the grout manufactures directions.

3. Apply the grout with the grout float. Work the grout into the joints making sure they are full. It helps to pack the grout into the joints by pressing hard on the grout float.

4. Once all the grout joints are full, hold the float at a 45-degree angle and move it diagonally across the grout joint to remove excess grout. It’s best to work in small sections so the grout does not dry too fast.

5. Once all the tile is grouted, clean the tile with a clean wet sponge. It will be necessary to rinse several times. I prefer using two buckets and two sponges. Change the water often.

6. Allow the grout to sit at least 24 hours. Occasionally a light grout film will be present after the grout dries. To remove this film, simply buff with a clean dry cloth.

7. Avoid walking on the floor or using the shower for at least 24 hours.

GROUT SEALING

In order to keep your new grout or newly cleaned grout clean, it should be sealed. There are so many sealers on the market today. Which ones are best? Which ones really work?

It can be very confusing trying to choose a sealer to protect grout. In the past several years the janitorial industry have bombarded the market with hundreds of products to seal & protect grout.

Fortunately, all of these products fall into only two major categories:

1. Coatings

2. Impregnators or penetrating sealers.

Coatings:

Coatings are sealers that place a sacrificial coating on the surface of the grout. This is a film that lays on top of the grout acting as a barrier to prevent water, oil and dirt from entering the pores.

Coatings can be classified into two general types:

1. Strippable

2. Permanent.

Strippable coatings:

Strippable coatings are coatings that are designed to be easily stripped or removed from the surface of the grout. These coatings are made of polymers consisting of acrylics, styrene, polyethylene and others. They are usually water based. Many of the janitorial products are water based polymer type coatings. To identify these coatings look for terms on the label such as "metal cross link”,” high solids”,” high speed", "acrylic", "thermoplastic", etc. When in doubt, ask. There are hundreds of different formulas of strippable coatings.

Permanent coatings:

Permanent coatings are coatings that are very difficult to remove. They are made of solvent-based polymers such as polyurethane, epoxies, etc. These are not recommended for grout.

Impregnators or penetrating sealers:

Impregnators are designed to penetrate below the surface of the grout and deposit solid particles in the pores or to coat the individual minerals below the surface. Water, oil and dirt are restricted from entering.

Impregnators can be solvent or water based and usually contain silicone, siloxane, silane, methyl silicate or other similar silicon derivatives as well as Fluro alphatic polymers.

Impregnators can also be classified into two types:

1. hydrophobic- water repelling

2. oilophopic- oil repelling.

Hydrophobic impregnators

Hydrophobic impregnators are designed to repel only water and water based chemicals. A hydrophobic impregnator would repel fruit drinks, coffee, tea, soda, etc..

Oilophobic impregnators

Oilophobic impregnators are designed to repel water and oil based liquids. Cooking oil, grease, body oils, etc. would be repelled by a oilophobic impregnator.

An oilophobic impregnator will always be hydrophobic, but a hydrophobic impregnator may not be oilophobic. Be sure to read product labels carefully to determine if they are hydrophobic or oilophobic. Some products are listed as oil resistant. Oil resistant and oil repellant are entirely different. Oil resistant will only slow down the absorption of oil into the grout. Oil repellant will prevent oil from entering the grout. Again, read product labels carefully. Be sure you are buying the right product for your particular situation.

COATING OR IMPREGNATOR?

How do you make the determination between a coating or an impregnator? They both have their advantages and their disadvantages. The following summary should be studied carefully when choosing the proper product:

Coating-Advantages;

Coatings are sealers that place a protective, sacrificial layer on the surface of the grout.

1. Coatings are generally economical. The initial application is relatively low.

2. Coatings are difficult to apply since you must apply them with a brush or applicator, which can be very tedious.

3. Coatings generally will provide a sacrificial coating. This layer will take most of the wear, preventing wear of the grout

Coatings-Disadvantages

1. Since most coatings are typically softer than the grout itself, they will usually scratch, mar and scuff very easily, showing traffic patterns soon after application. This will require re-application.

2. Coatings can build up and can cause an unsightly appearance, producing an unnatural look.

3. Poor quality coatings can turn yellow. This is especially true if the grout is exposed to UV light.

4. Coatings require frequent stripping and reapplication. The chemicals and abrasives used in the stripping process may cause damage to the grout. Typically, certain stripping pads and stripping brushes can also cause damage.

5. Certain coatings may block the breathing capability of the grout. Moisture can become trapped below the surface and may lead to the grout falling apart

Impregnators-Advantages

1. Most impregnators will not change the appearance of the grout.

2. Most impregnators do not require frequent applications. Since the impregnator is below the surface, it will generally last several years before reapplication is necessary.

3. Most impregnators are not affected by UV light since they are below the surface where UV light cannot penetrate. For this reason they can be used outdoors.

4. Impregnators are typically hydrophobic, while some are oiliophobic.

Impregnators-Disadvantages

1. Impregnators that are solvent-based produce noxious and flammable vapors during application.

2. Solvent-based impregnators are harmful to the environment producing high VOC (volatile organic compounds). For this reason, some are restricted in certain states. Always check the MSDS sheet.

3. The initial cost of most impregnators is relatively high.

5. Impregnators in general cannot be used below grade to resist hydrostatic pressure.

When choosing the proper product for protection, the above guidelines should help. Always talk with the manufacture or distributor, and let them know where you plan to use their product. They can be very helpful if you tell them all the conditions that apply.

GROUT SEALING-PENETRATING

1. Clean the grout thoroughly with a good grout cleaner or using the cleaning procedure described above. Allow the grout to dry thoroughly.

2. Pour a small amount of sealer on the floor and spread with a string mop or lambs wool applicator. For showers and walls use a terry cloth rag to apply the sealer.

3. Allow the sealer to penetrate into the grout for several minutes. Apply additional sealer if needed.

4. Once all the sealer is applied, buff any remaining sealer from the tile with a dry cloth. If you are sealing a large area, a floor machine may be used.

5. Try to avoid spilling anything on the grout for several days. Some sealers take this long to cure. However, you can walk on the floor once it is buffed.

GROUT SEALING-COATING

1. Clean the grout thoroughly with a good grout cleaner or using the cleaning procedure described above. Allow the grout to dry thoroughly.

2. Apply the sealer with a small brush or applicator. Some sealers come with a self-dispensing applicator. Work in small areas and avoid getting any sealer on the tile. It helps to keep a clean rag handy in case you accidentally get some on the tile.

3. Allow the sealer to dry thoroughly before walking on the floor or using the shower.

As you see, this procedure is very time consuming. I prefer the penetrating type for this reason.

GROUT COLORING

Yes, it is possible to change the color of your grout without replacing it. Coloring your grout also will seal it preventing it from getting soiled.

Before you can color your grout you must clean it and perform an adhesion test to make sure the grout coloring will stick and not peel.

Grout coloring can be purchased at most home centers and tile supply houses.

The following adhesion test must be performed before coloring the grout.

Grout Coloring Adhesion Test.

1. Clean about one foot of grout using the grout cleaning procedure in this article.

2. Dry the area with a hair dryer or heat gun. Make sure the grout is thoroughly dry.

3. Apply a small amount of grout coloring with a paintbrush to the cleaned area.

4. Dry the grout coloring with the hair dryer. It is best to allow it to dry overnight if time permits.

5. Once the color is dry, take a piece of masking tape and apply it to the grout color. Rub the tape with your finger to make sure it sticks to the color.

6. Now, quickly remove the tape. If the grout coloring sticks to the tape, then the chances it won’t stick. In this case you will have to try acid washing the grout and repeating this test. If the coloring remains on the grout, then you can proceed to coloring.

GROUT COLORING PROCEDURE

1. Make sure you have cleaned the grout and have performed the adhesion test as outlined above.

2. Apply the grout coloring to the grout with a small paintbrush or applicator. Do not apply to heavily. It is best to apply two thin coats then one heavy coat.

If you have an airbrush, grout coloring can also be applied with it.

Do not worry about getting the color on the tile. It should clean off easily on ceramic tile. Marble, granite and stone may be a problem. Check to make sure the grout coloring does not absorb into the stone. If it does it may be necessary to mask the tile.

3. Allow the coloring to dry. See label instructions for dry times.

4. Once dry, remove the excess coloring from the tile surface with a green scrub pad and some warm water and dish detergent.

If any coloring is removed you can touch up later.

It’s that simple. Just take your time.

GROUT MAINTENANCE

To keep your grout looking new, it is best to avoid harsh cleaners. I recommend a neutral cleaner. A neutral cleaner is not acid or alkaline and has a Ph of 7. Neutral cleaners can be purchased from most janitorial supply houses.

It is especially important to use mild cleaners with colored grout. The coloring will eventually come off and will require re-application.

Frequently Asked questions about sealers, penetrating sealers and impregnators

Frequently Asked questions about sealers, penetrating sealers and impregnators

By Frederick M. Hueston

The use of sealers and impregnators on granite and other stone is becoming a standard practice in our industry. With this practice comes a little controversy on the use of these products. The following are some common questions I get on this subject.

Q. What is a sealer, impregnator and penetrating sealer? How do they differ?

The terminology used in the stone industry can be confusing and often misused. The following are some definitions that will help clear up this confusion;

Sealer- According to Webster’s Definition a sealer is a coat (as of size) applied to prevent subsequent coats of paint or varnish from sinking in. In the other industries such as the cleaning and janitorial industry a sealer is similar in that it is a coating that is placed on the surface of a substrate to seal it so something else can be applied. In the stone industry a sealer is also defined as a coating. In the scientific community the proper description is called a "Film Former," since when applied it forms a film on the surface of the stone.

Impregnator- Again, according to Webster’s definition to impregnate means to cause to be filled, imbued, permeated, or saturated. In the stone industry the same definition applies. Impregnators penetrate below the surface of the stone and protect from within. There is no coating or filmed formed on the surface of the stone.

Penetrating Sealers- Penetrating sealer is really a type of oxymoron if we go by the pure definition of each term. If a sealer is a coating that sits on the surface then how can it also penetrate into the stone.? This term however is often used interchangeable with an impregnator. Technically you would expect that a penetrating sealer penetrated below the surface and also forms a film on the surface of the stone. While there are products that can do both, most of the products, with few exceptions our industry do not.

Some other terms used in our industry are also worth mentioning:

Consolidents- A consoildant is a product that is used on stone to bind loose particles of the stone back together. In otherwords to glue loose stone together. These are often used on historic stone structures that become loose and brittle. A condition known as sugaring, since the fine stone particles are like sugar. There are numerous types of consolidants and it is beyond the scope of this article to go into more detail. Most impregnators do not act as consolidants.

Q. How do impregnators work

Impregnators work by reducing the pore size of the stone by filling the pores with a resin. The resins are small enough to prevent complete blockage of the pores, so the stone will still allow vapor to pass through while not allowing a liquid to penetrate. Some of the resins used are very hydrophobic and/or lyophobic. In other words they repel water and oil, depending on the type of resin used.

Note: in most of the literature you will see the word Oilophobic, meaning oil repellent. This is the incorrect term and this word does not exist. The proper term for oil repellent is Lyophobic.

Q. Why is breathability necessary

All stone must transpire vapor. In other words, it must breathe. If a stone's pores are totally blocked vapor will condense within the stone and the stone will be saturated with moisture. This can lead to numerous problems such as spalling, iron oxidation, etc. The moisture can also carry soluble salts which are often deposited on the surface of the stone(efflorescence), If the salts are not allowed to escape to the surface, they will be deposited in the pores of the stone and cause deterioration.

Q. What types of impregnators are there?

Impregnators can be broken down into several categories. They can be water based or solvent based. Most impregnators also contain one of two main ingredients: Silicon derivatives or fluoro alphatics. In generally the silicone types repel water and the fluoro types repel both water and oil. Many companies are going to strictly water based formulas due to the fact that they are safer to use, have little order and are better for the environment.

Q. Are sealers safe for food handling areas?

This will all depend on the manufacturer. Generally once the impregnator has dried and cured it should be safe for most food handling situations. However, to be sure check with the products manufacturer.

Q. What problems do you see with impregnators

The problems I have seen to date are few and almost always caused by misapplication of the product. If the impregnator is left on the surface of the stone and the excess is not removed, it can cause the stone to be sticky, making removal difficult.

Recently I have seen some solvent based impregnators reacting to resined slabs causing clouding or discoloration.

Another problem is applying an impregnator to a wet stone. If the stone is wet, the impregnator will not penetrate and hence it wont perform as expected.

Overall, most impregnator are trouble free.

Q. How often must an impregnator be applied

This will also depend on the type and use of the stone. I generally recommend that they be applied about once per year. More frequently applications may be necessary for commercial applications.

Q. Does all stone need to be sealed?

This is an ongoing debate in the industry. There are those who say that all stone needs to be sealed and others who say that only some very porous stone needs sealing. The best test is to perform a simple absorbency test as follows: Place about a teaspoon of water on the stone surface and allow it to sit for one to two minutes. If the stone becomes dark under the water, which indicates that it is absorbent, then the stone will need to be sealed.

Q. Are sealers and impregnators UV resistant?

Again, this will depend on the type. In general, since they work below the surface most will be UV resistant. Remember that UV light is very powerful and will eventually have an effect on any sealer or impregnator. Most topical sealers are not UV resistant and will discolor over time.

The above information is based on current knowledge, but one must be aware that the chemistry of impregnators and sealers can and will change. My best advise is to keep up with current trends and ask lots of questions when looking into any new product.

Frederick M. Hueston

www.stoneforensics.com

Is Your Stone Business Taking your Breath Away?

Is Your Stone Business Taking your Breath Away?

Frederick M. Hueston, Technical editor

Does your shop cut, grind or hone stone dry. If so, you may want to pay attention to this article. Dust created from cutting and grinding certain types of stone will emit silica in the air. If you or your workers are not using the proper respiratory protection, you could be exposing yourself and your workers to serious health problems. Breathing silica dust can cause a disease known as Siliceous. More than 250 people each year die from this disease and over one million workers in the US are exposed to silica dust. The really bad news is that there is no cure for it. The good news is, it is very preventable.* The way to prevent silicosis is simple...cut, grind and polish all your stone wet and you wont have to worry about it.

What stone types contain silica?

All granite as well as certain slate and some marbles may contain harmful silica dust. I would make the assumption that all granites and slates contain silica. Most marble except for a few green varieties have silica. Limestone generally will not contain silica, although there are a few which may. All quartzite’s and stone containing quartz will have silica.

The following article was taken from the Washington State Department of Labor and Industry(www.lni.wa.gov/wisha/hazalerts/hazmay98.htm). Most states will have there own exposure limits and I would encourage you to check with your state Department of Labor. OSHA also has a federal limit which you should be aware of. OSHA also has some excellent info on siliceous and protecting yourself on their web site at www.osha‑slc.gov/SLTC/silicacrystalline.

*www.osha‑slc.gov/SLTC/silicacrystalline/

Designing a Sustainable (Green) Stone Floor Maintenance Program

Designing a Sustainable (Green) Stone Floor Maintenance Program

By Frederick M. Hueston

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.

he 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

Designing a Stone Floor Maintenance Program

Designing a Stone Floor Maintenance Program

Program Guidelines

Step 1. A good maintenance program starts with proper identification of the stone. Is it granite, marble, quartzite 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 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. 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 filled with a polyester.

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 chemically stripped or ground off to determine the condition of the stone. 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 maintenance program can begin.

Step 4. Once the stone is restored to like new condition, then and only then will a 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 good quality silicone based

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).

Step 5. Daily Maintenance

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 neutral cleaner or stone soap. Neutral cleaners are defined as surfactant type detergents that have a Ph of 7. Acidic and alkaline cleaners should not be used on a regular basis. Be sure to follow the directions very carefully. Too much cleaner may leave a film and cause streaking.

Why Does Stone Shine?

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.

Restoration

Natural stone was the first building material used by man. Its care and maintenance is one of the oldest tasks performed by our ancestors. The above guidelines were developed by our years of experience with this beautiful material and with the addition of modern science will provide many years of beauty.

Written by

Frederick M. Hueston