How to make a slippery floor safe
There are many treatments that can be purchased and applied to a tile surface to make it slip resistant. These treatments fall into two categories: Coatings or treatments which chemically or physically alter the surface of the tile.
Coatings:
Coatings can be waxes, acrylics or other commercially available products. The coating places a thin layer of material on the surface of the tile. The tile will than be as slippery as the coating itself. Warning: not all coatings provide slip resistance. In fact some coatings will make a floor more slippery. Before specifying a coating, contact the manufacturer of the coating and ask for slip resistance test data. Many of the coating manufacturers are very familiar with slip resistance. Make sure the coating can be used on the tile surface you are using. Certain coatings will not adhere to polished stone or porcelain and require coatings specified for these surfaces.
Treatments:
There are now available special treatments that can be applied to the surface of tile to render it slip resistant. These treatments are primarily hydrofluoric acid. The acid attacks the surface of the tile and creates microscopic holes. This is what is typically called etching of the surface. This process works effectively on many surfaces but can decrease the service life of the tile. Once the surface is treated with this method maintenance will increase. Since these treatments contain a very dangerous acid, it should only be applied by trained individuals. Contact your local tile supply store for recommended contractors.
The issue of slip-resistance is of major concern in the US. Lawsuits are on the increase as con artists continue their search for the big payoff. Large hotels, banks and other big corporate building owners are their main targets but they are also targeting the small business. The corner food store and the local gas station are not exempt from these flim flam artists.
This is not to say that there are not times when a floor surface is not unsafe. Many factors contribute to the slipperiness of the floor. Water, grease, oil and debris scatted on the floor all can contribute to slipperiness. The competent architect and designer cannot control what happens to the floor after its installed but he/she can get it started properly.
How to Minimize Slip/Fall Accidents
Although it will be impossible to prevent all slip/fall accidents there are several precautionary procedures that building owners, cleaning companies and others can take to minimize risk. The following is some suggestions and is not intended to replace legal advise if an accident occurs:
1. Pay attention to areas where water and/or spills occur. A walk off mat should be placed inside the entrance of doors during a rain storm. When floor tile gets wet, the COF* may decrease causing a fall. Mats should be placed prior to the first drop of rain. Pay attention to areas where food is served or carried. Foods and drinks can create an ice like condition on the floor and any spills should be picked up as soon as they occur.
2. If the floor tile is maintained by stripping and waxing, this procedure should be done at night when there is no one around to fall. Daily wet mopping should also be performed at night during off hours.
*Coefficient of Friction
3. Always place wet floor signs in all areas you may be working in. This applies for all times of the day or night. It is also a good idea to train your floor cleaning personnel to warn people who may walk across the floor that it might be slippery.
4. Keep accurate records. It is surprising how many cleaning companies fail to keep any record of maintenance on a tile surface. Accurate record keeping says that you are responsible and that you generally care about safety. Include in your records the following information:
* Name brands of all products used on the floor
* Procedures that are performed on the floor and how often. Be specific.
* Who performed these procedures.
It is a good idea to keep a daily log of the maintenance procedure. Designate one individual to keep track of the log and have him perform routine inspections of the floor and record what he found during his inspections. If a legal suit is filed this information will be quite helpful in proving you are competent and hopefully not at fault.
5. Get slip/fall insurance. Every building owner should carry slip/fall insurance. Some of the products used on the floor will also carry slip/fall insurance. This insurance is designed to protect the coating manufacturer and you should not rely entirely on theirs. Get your own policy.
What to do when some falls:
O my, someone just slipped and fell, what should you do?
1. Treat the victim with kindness and courtesy. Do not administer medical treatment unless you happen to be qualified to. If necessary call an ambulance. Also offer to call their family. Show care and concern.
2. Look at the victim’s clothing and especially his/her shoes. Take notice of how worn they are and the overall condition. Once the victim leaves, record this information in your log or on a separate report. This is important, remember it takes two surfaces to slip, if the victim is wearing worn shoes part of the blame may be placed on their neglect.
3. Look carefully at the area where the victim fell. Is there water, grease, a banana peel? Record in the log any thing you find.
4. Did any one else see the fall. If so, take a statement from them. Record this in a special report and get their name, address and phone number.
5. Record the time and location of the fall. Pay special attention to the weather conditions. Was it raining, snowy or what.
6. Did you notice how the victim walked. Did he/she stumble or appear as if they were under the influence of alcohol or drugs. If possible record their behavior and how they walked or ran before the fall.
7. If you have a camera, take pictures of the victim and the area where they fell.
8. Fill out an accident report and do not leave out any detail. Use a separate sheet of paper if necessary.
Following the above suggestions will help considerably when involved in a slip/fall case. Your attorney will love you for it.
One Final Word
The legislation and rules concerning COF and slip/fall can and probably will change. It is a good idea to consult with an expert in slip/fall and to keep up to date with any new rule, law or recommendation that may sneak up
COF-Coefficient of Friction
Slip resistance is measured by the ratio of forces required to move one surface over the other under a given vertical force. In other words, it takes two surfaces to determine slip resistance. The floor tile is one surface and the bottom of ones shoe is the other surface. This ratio is what we call the coefficient of friction(COF).
COF can be measured in two different ways and can cause confusion amongst those unfamiliar with the science of slip resistance. When the COF is measured from a resting position it is called the “Static COF”. When it is measured when the surfaces are in relative motion it is called the “Dynamic COF”. The dynamic COF is very difficult to measure and almost all portable and laboratory meters measure only the static COF. It is important to know this difference since you will see both measurements in the literature. Most measuring devices(Slip meters) will refer to the static COF. The measurements you will find in the literature and those discussed here will be the Static COF. A COF of 0.5 is considered to be a slip resistance surface. The higher the COF the less slippery the surface. It is possible to have too high a COF. In other words the surface can be too slip resistance and an individual would find it difficult to walk on.
How to Measure Slip Resistance
There are basically two types of machines that can measure static COF, Permanent laboratory models and portable field models commonly refer to as pull meters. The most popular and widely accepted laboratory slip meter is the James Machine. The James Machine uses an 80 pound weight that is applied through an arm to a leather shoe placed on a panel. The panel and the leather shoe are moved horizontally. The distance the panel moves before slipping is measured and recorded on a chart and is the coefficient of friction. The James Machine was invented in 1940 and was the machine which established the 0.5 COF as the minimum for slip resistance. This standard was accepted in 1953 by the Federal Trade Commission . Many still consider the James Machine as the only true slip tester.
There are also many portable slip meters on the market which claim to measure the static COF. The American Society for Testing and Materials(ASTM) recognizes several portable meters. When purchasing these meters make sure they comply with ASTM C-1028 which is the recognized slip test for tile flooring. For further information on slip meters contact ASTM at the following address: 1916 Race Street, Philadelphia, PA 19103-1187
Written by
Frederick M. Hueston
The National Training Center for Stone & Masonry Trades
828-301-9796
fhueston@aol.com
www.ntc-stone.com
Thursday, December 6, 2007
Epoxy vs Polyester for Stone Laminations
Epoxy vs. Polyester. Are You Using The Right Adhesive?
Frederick M. Hueston
I was sitting in my office when I received a call from a hotel manager about a swimming pool coping that was falling apart. I asked him what was falling apart and he told me that the stone was falling into the pool. I got in my truck and made my way over to the hotel and discovered that the swimming pool had a travertine coping and all the laminations where failing and falling off. I examined the laminations closely and discovered that Polyester was used in the laminations.
Several weeks later I got a similar call from a home owner who had a similar problem but this time the laminations where failing on her new granite countertop. Again, upon inspection, the adhesive used was polyester.
How many of you use polyester for your laminations and other applications where you are bonding two pieces of stone together? If you do, your laminations are prone to failure.
There are many choices when it comes to the selection of adhesives and it can get very confusing. The following is a brief explanation of the two most popular adhesives in the stone industry and a guide as to where to use what type:
Epoxy or Polyester?
Polyester
Polyesters use a hardening agent to catalyze the curing reaction. Most polyesters use a peroxide hardening agent.
Of all the adhesives available polyester is the least inexpensive but also has the weakest bond strength. It also has a very high shrinkage rate and the highest water absorption amongst all the adhesives. It is also very prone to UV degradation and will crack and become brittle.
For this reason polyester should never be used for laminations or for repairs in wet area or used outdoors.
Polyesters are good for small repairs for indoor stone applications such as filling and seams or in applications where bond strength is of no concern. The bond strength of polyesters is less than 500 PSI.
Epoxy
Epoxies are two parts labeled part A and Part B. Most epoxies are mixed at a ratio of 2/1 but some are 1/1.
Of all the adhesives used in the stone industry epoxies have the strongest bond. Bond strengths can exceed 2000 PSI. It has a lower shrinkage rate than polyester and is more UV stable with a lower water absorption rate.
It is clear that if you want great adhesion, epoxy is the stronger adhesive. I always recommend using epoxy for laminations and rodding and anywhere else you want the stone to stick and not fall apart.
A little experiment.
Here is a crude test that I perform when testing adhesives for bond strength.
Take two pieces of stone with the polished sides facing each other. Place some adhesive on the polish faces and clamp them together. Let the clamped pieces set overnight. The next morning take a hammer and try to break them apart. A weak glue, such as polyester will break clean, leaving the face of the stone intact. A strong adhesive such as an epoxy will be so strong that the face of the stone will spall off. This indicates that the adhesive bond is stronger than the natural bond of the stone.
Adhesive Grades:
All adhesives are available in various viscosities ranging from low to high. The following are the most popular choices
Knife Grade- Consistency is similar to spackling putty or creamy peanut butter.
Flowing Grade- Consistency of a motor oil
Penetrating Grade- Consistency of water
Super Penetrating Grade- Consistency of a solvent such as mineral spirits or paint thinner
Generally knife grades are used for repairs for fills that are over 1/16 of an inch wide. Flowing grades are used for repairs smaller than 1/16th and for laminations and rodding.
Penetrating and super penetrating grades are rarely used by fabricators but are used for resining stone and for applications where an adhesive is need to penetrate very small pores.
Adhesive Colors
Today’s adhesives are available in a number of colors however there may times when you need to add coloring. Many of the adhesive manufacturers have tints that you can use. If you in a pinch I have found that artist oil colors work well for most polyesters, however for epoxies you will need to use tints designed specifically for them.
General Properties
Temperature
All adhesives are sensitive to temperature and humidity. This means that cure times will vary. Adhesives will cure faster with increasing temperatures and slower at cooler temperatures.
Temperature will also affect the viscosity. Higher temperature will thin the adhesive.
Tip: There are several heated dispensers for epoxies that work very well for faster cure times and easier flowing.
Cure Time
The general rule of thumb for most adhesives is the slower the cure time the stronger the bond. Epoxies with a 7 hour cure time are going to be much stronger than an epoxy with a five minute cure time.
If too much hardener is added to polyester you will increase the cure time but you will reduce the bond strength.
UV exposure
Nothing is completely UV proof; however epoxies are more UV resistant than polyesters and are the adhesive of choice for outdoor exposure.
Moisture
Polyester is very sensitive to moisture and for that reason it should be avoided in wet areas such as showers. Epoxy has a much higher tolerance for moisture and is the adhesive of choice in wet areas.
When using polyester you must make sure that the stone is completely dry. Epoxies can tolerate some moisture.
Polyester
The stone must be completely dry
If you do not thoroughly mix the resin and hardener it will probably cure anyway
You can use most colors to tint
Many varieties available
Good adhesion when prepared properly
Can easily be used for patching
Stone surface must be abraded before sticking
Should NOT be used for exterior or in moist locations
Quick curing time (normally 10 minutes to 1 hour depending on the product and the weather)
Epoxy
Stone can be a little moist
Resin and hardener must be thoroughly mixed to cure
You should use only colors made for epoxy
Not as many varieties available
Great adhesions when prepared properly
Not as easily used for patching
Stone surface should be abraded, but it will stick to a smooth surface also
CAN be used for exterior and moist locations
Slow curing time (normally 7 hours depending on the product and the weather)
Use Chart
Laminations- Epoxy
Indoor repair- Polyester
Rodding- Epoxy
Outdoor Repair- Epoxy
Mending- Epoxy
Seams- Polyester
Attachments- Epoxy
Mr. Hueston is the founder of The National Training Center for Stone and Masonry Trades (www.ntc-stone.com) and Stone University (stoneuniversity.org).
Frederick M. Hueston
I was sitting in my office when I received a call from a hotel manager about a swimming pool coping that was falling apart. I asked him what was falling apart and he told me that the stone was falling into the pool. I got in my truck and made my way over to the hotel and discovered that the swimming pool had a travertine coping and all the laminations where failing and falling off. I examined the laminations closely and discovered that Polyester was used in the laminations.
Several weeks later I got a similar call from a home owner who had a similar problem but this time the laminations where failing on her new granite countertop. Again, upon inspection, the adhesive used was polyester.
How many of you use polyester for your laminations and other applications where you are bonding two pieces of stone together? If you do, your laminations are prone to failure.
There are many choices when it comes to the selection of adhesives and it can get very confusing. The following is a brief explanation of the two most popular adhesives in the stone industry and a guide as to where to use what type:
Epoxy or Polyester?
Polyester
Polyesters use a hardening agent to catalyze the curing reaction. Most polyesters use a peroxide hardening agent.
Of all the adhesives available polyester is the least inexpensive but also has the weakest bond strength. It also has a very high shrinkage rate and the highest water absorption amongst all the adhesives. It is also very prone to UV degradation and will crack and become brittle.
For this reason polyester should never be used for laminations or for repairs in wet area or used outdoors.
Polyesters are good for small repairs for indoor stone applications such as filling and seams or in applications where bond strength is of no concern. The bond strength of polyesters is less than 500 PSI.
Epoxy
Epoxies are two parts labeled part A and Part B. Most epoxies are mixed at a ratio of 2/1 but some are 1/1.
Of all the adhesives used in the stone industry epoxies have the strongest bond. Bond strengths can exceed 2000 PSI. It has a lower shrinkage rate than polyester and is more UV stable with a lower water absorption rate.
It is clear that if you want great adhesion, epoxy is the stronger adhesive. I always recommend using epoxy for laminations and rodding and anywhere else you want the stone to stick and not fall apart.
A little experiment.
Here is a crude test that I perform when testing adhesives for bond strength.
Take two pieces of stone with the polished sides facing each other. Place some adhesive on the polish faces and clamp them together. Let the clamped pieces set overnight. The next morning take a hammer and try to break them apart. A weak glue, such as polyester will break clean, leaving the face of the stone intact. A strong adhesive such as an epoxy will be so strong that the face of the stone will spall off. This indicates that the adhesive bond is stronger than the natural bond of the stone.
Adhesive Grades:
All adhesives are available in various viscosities ranging from low to high. The following are the most popular choices
Knife Grade- Consistency is similar to spackling putty or creamy peanut butter.
Flowing Grade- Consistency of a motor oil
Penetrating Grade- Consistency of water
Super Penetrating Grade- Consistency of a solvent such as mineral spirits or paint thinner
Generally knife grades are used for repairs for fills that are over 1/16 of an inch wide. Flowing grades are used for repairs smaller than 1/16th and for laminations and rodding.
Penetrating and super penetrating grades are rarely used by fabricators but are used for resining stone and for applications where an adhesive is need to penetrate very small pores.
Adhesive Colors
Today’s adhesives are available in a number of colors however there may times when you need to add coloring. Many of the adhesive manufacturers have tints that you can use. If you in a pinch I have found that artist oil colors work well for most polyesters, however for epoxies you will need to use tints designed specifically for them.
General Properties
Temperature
All adhesives are sensitive to temperature and humidity. This means that cure times will vary. Adhesives will cure faster with increasing temperatures and slower at cooler temperatures.
Temperature will also affect the viscosity. Higher temperature will thin the adhesive.
Tip: There are several heated dispensers for epoxies that work very well for faster cure times and easier flowing.
Cure Time
The general rule of thumb for most adhesives is the slower the cure time the stronger the bond. Epoxies with a 7 hour cure time are going to be much stronger than an epoxy with a five minute cure time.
If too much hardener is added to polyester you will increase the cure time but you will reduce the bond strength.
UV exposure
Nothing is completely UV proof; however epoxies are more UV resistant than polyesters and are the adhesive of choice for outdoor exposure.
Moisture
Polyester is very sensitive to moisture and for that reason it should be avoided in wet areas such as showers. Epoxy has a much higher tolerance for moisture and is the adhesive of choice in wet areas.
When using polyester you must make sure that the stone is completely dry. Epoxies can tolerate some moisture.
Polyester
The stone must be completely dry
If you do not thoroughly mix the resin and hardener it will probably cure anyway
You can use most colors to tint
Many varieties available
Good adhesion when prepared properly
Can easily be used for patching
Stone surface must be abraded before sticking
Should NOT be used for exterior or in moist locations
Quick curing time (normally 10 minutes to 1 hour depending on the product and the weather)
Epoxy
Stone can be a little moist
Resin and hardener must be thoroughly mixed to cure
You should use only colors made for epoxy
Not as many varieties available
Great adhesions when prepared properly
Not as easily used for patching
Stone surface should be abraded, but it will stick to a smooth surface also
CAN be used for exterior and moist locations
Slow curing time (normally 7 hours depending on the product and the weather)
Use Chart
Laminations- Epoxy
Indoor repair- Polyester
Rodding- Epoxy
Outdoor Repair- Epoxy
Mending- Epoxy
Seams- Polyester
Attachments- Epoxy
Mr. Hueston is the founder of The National Training Center for Stone and Masonry Trades (www.ntc-stone.com) and Stone University (stoneuniversity.org).
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