Some Answers to Frequently Asked Wood Floor Questions

Considering a new hardwood floor? Here are some answers to frequently asked hardwood questions Read more

Checks in Wood Veneer

Understanding and Minimizing Veneer Checking on Furniture Panels

by

Craig L. Forbes

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Wood Floors and Finishing

Wood Floors and Finishing

Floor sanding can be done by hand, but electrically driven sanding machines are used almost exclusively today. Read more

Testing Methods for Determining Hardness of Wood Floors

Janka Test

The Janka (or side) hardness test measures the amount of force required to embed a .444-inch steel ball to one-half of its diameter in wood. It is known as one of the best measures of the ability of a wood species to withstand denting and wear. Read more

Tips For Protecting Hardwood Floors

• High heel shoe damage: A 125-pound person in high heels exerts pressure of approximately 2000 pound of pressure per square inch. If the protective cap on a pair of high heels has worn down the steel support rod can become exposed. This rod will dent and pit wood, fracture tiles or stone and puncture vinyl.

• Protective pads: Always use felt style protective pads on furniture legs. Felt pads allow the furniture to be moved easily without scratching or denting the finish on your floor. Felt pads also reduce noise by acting as a sound deadening barrier. Routinely check your felt pads for dirt and grit that has become imbedded in them. A dirty or worn felt pad can damage a floor.

• Walk off mats: Using walk off mats at all exterior doors will trap dirt and sand. Remember that grit like soil is as abrasive as sandpaper and will damage most types of floor covering including wood, ceramic, laminate, sheet vinyl, linoleum, carpet and others. All rugs should allow wood floors to breathe. Avoid rubber-backed or non-ventilated rugs. Move area rugs occasionally as certain chemicals in wood oxidize in strong light causing the wood to change color. Moving rugs will help to avoid an uneven appearance.

• Use Area rugs in high traffic and pivotal traffic areas, e.g. at the ends of steps and near doorways.

• Wood floors should never be wet mopped. Excessive moisture can damage wood by causing it to swell and cup. If moisture is used the mop should only be slightly damp.

• Potted plants: Never place a potted plant directly on the surface of a hardwood floor. Even plants that are placed in waterproof saucers can damage the wood by condensation under the saucer. Plants need to be elevated so the air will circulate below. Place the plant on a stand or trivets.

• Vacuum or sweep regularly: This needs to be done on a routine basis to remove dirt and grit prior to cleaning you wood floor. Dirt is a major cause of damage to all types of floor covering.

• Dust treatment and furniture polish should never be used on a hardwood floor. These treatments may cause a floor to become slick and can dull the finish.

• Immediate cleanup of spills: It is essential that food or spills be cleaned up immediately using a soft cloth and the manufacturers recommended cleaner. Dry spills and abrasives are best cleaned up with a vacuum or broom.

Hardwood Flooring Grades

Hardwood flooring is manufactured in many different species and grades. The hardwood flooring grading system usually falls into three main areas; select, natural and rustic. Depending on the manufacturer there can be variances in the grading system within each of these area and some manufacturers have proprietary grades

Select, Select & Better, Prime, Pacific & A grade

Select floors are higher end floors. Select floors are graded to have the best selection of wood from the tree. These grades offer more uniformity of color selection with very few knots or sapwood or mineral ingress.

Natural, Character & AB Grade

Natural grade floors are graded to give a varied selection of wood from the tree and a more natural look. The floor will have small and closed knots and more variation of color selection and some mineral ingress. These floors will generally be priced in the mid range.

Rustic, Factory, Tavern, ABCD & CD Grade

 Rustic grade floors are graded to have a high percentage of variation in wood selection. This grade has the tendency to offer a lot of color and variety with knots and texture.  This is a look that you will either love or hate. The knots may or may not be filled depending on the manufacturer and design of the product.  This grade may also have visible splits and shakes and cracks in the lacquer and there will be visible mineral ingress. These floors are generally but not always at the lower end of the budget range. Some flooring manufacturers are deliberately creating these rustic looks and are marketing them as a higher end floor.

CD Grade

CD grade wood is among the lowest of the rustic grades. (See above). As with the other rustic grades it has a lot of interesting character that you really enjoy having or do not like. While you may not install this grade in a formal setting it can add a lot of warmth to a more casual environment.

Cleaning Hardwood and Bamboo

With the many varieties of wood, there are many natural colors and these can be stained to a completely different color. 

Bamboo is a light color naturally. During manufacturing, all strips are subjected to a bleaching process where strong oxidizing agents such as hydrogen peroxide are used to suppress color differences and oxidize troublesome organic matter. During this process, care must be taken not to soften the bamboo or leave residual oxidizing agents that can react with finishes and cause them to peel at a later date.

Most manufacturers have both a light and a dark color.  The dark color is obtained not by staining but by carbonizing.  A variety of finishes are used with site finished and factory finished floors. 

Penetrating Seal: The sealer penetrates into the wood or bamboo where it hardens.  Since the sealer has penetrated it will wear only as the floor wears.  Penetrating sealer will not chip or scratch.

Maintenance

• Usually maintained with a thin application of wax.
• Refinish worn areas by cleaning and applying another coat of sealer or using a reconditioning product.  Sanding will usually not be required. 
• With a sealer/wax system two coats of penetrating sealer is recommended by most manufacturers.

Polyurethane “Swedish finish”, moisture cure urethane and water-based urethane are a few of the many blends of synthetic resins, plasticizers and other film-forming ingredient.  Is polyurethane is durable and moisture resistant, available in high, low and semi gloss.  Urethanes other than moisture cured are a good choice for higher moisture areas such as kitchens.

Oil Modified Polyurethane: Durable and moisture resistant.  Usually will take on an amber color with age.

Water Bases Urethane Acrylic: Clean I color, non-yellowing and durable.  Has similar advantages to oil modified without the odor of mineral spirits during application.

Moisture Cure Urethane: Hardens with a greater moisture resistance than the other surface finishes.  Usually available only in gloss.

“Swedish Finishes” (Acid cure urethane): Durable finish, usually harder than polyurethane’s, resist yellowing, clear in color.

Polyurethane with aluminum oxide: Exceptional hardness, more scratch resistant and longer gloss retention.

Stain & Wax Finish

Maintenance

• Following installation apply a coat of wax.
• Sweep or vacuum regularly to remove loose dirt before it scratches or gets ground into the surface.
• Buff floor between waxing to restore sheen.  A heavier buffing machine will give a higher sheen than a lightweight machine.  Use only fiber bristle brush.  Frequent waxing may be required in dry or damp weather climates or areas of high traffic.

Urethane Floors

Maintenance

• Clean per manufacturer recommendations after installation.
• Sweep and vacuum regularly.

Maintain with a manufacturer recommended product.

Hardwood Do’s and Don’ts

DO’S

• Install humidity controls.  The use of a dehumidifier or humidifier is critical in areas with frequent variations in temperature and humidity.
• Sweep with soft bristle broom or dust mop the floor daily.  Walking on dusty or dirty floors will damage the finish.
• Vacuum the floor regularly using a floor tool and not a beater brush.
• Clean spots from the floor by rubbing with a lightly dampened cloth.  Spray the cleaning product onto the cloth and not the floor. Use a cleaning product acceptable to the manufacturer.  Your dealer, installer or a wood flooring company can assist you with this.
• Purchase a “floor care kit” recommended by the installer or retailer.
• Dry up spills immediately.
• Use felt or similar soft protectors on the legs or feet of furniture.
• Use throw rugs at locations where soil may be tracked onto the floor or at areas subject to regular pivotal traffic such as in front of a kitchen sink, or sofa or chair.
• Area rugs should be moved occasionally so that natural fading of the floor will be evened out.
• Use mats at outside doors to assist keeping dirt and dust outdoors.
• Keep the outdoor walks and porches clean so dirt is not tracked on to the floor.
• Use barrel-type caster wheels or wide glides on furniture.
• Restore lost luster with topcoat dressing.
• Recoat worn surfaces before the bamboo or wood is exposed to avoid re-sanding.
• Have the floor professionally screened and recoated before wear on the finish is too severe.  This may be several years down the road depending on care and use.

DON’TS

• Do not use dust treatment sprays or chemicals.  These products may cause the floor to become slick or dull the surface.
• Do not use a vacuum beater brush, as it will damage the finish.  Use the vacuum floor tool.
• Do not wet mop the floor.  When using a damp mop, spray the cleaning product onto the mop and not by dipping the mop.  Remember that water is the number one cause of damage to a floor.
• Do not allow spills to dry on their own, wipe them up immediately.
• Do not regularly clean with water or water-based products. Clean only the soiled areas as needed.
• Do not use ammonia or ammonia products. Alkaline cleaners may cause strong yellowing and color changes.
• Do not use oil soap or oil soap products.
• Do not wax a urethane floor.
• Do not use rubber, foam-back or plastic mats as they may discolor floor.
• Do not wear spike or stiletto heeled shoes in rooms with wood or bamboo floors.  Such footwear can produce a dynamic load in excess of 1000 PSI, even when worn by a person of small or average build. Wearing a shoe in bad repair that has an exposed nail head can exert a force of 8,000 PSI, which is high enough to pulverize hardened concrete.  You are better off driving your car or walking an elephant on the floor.  The car has a load of 28 to 30 PSI and an elephant 50 to 100 PSI.

Bamboo and Wood Floors – The Effect of Water

The largest percentage of complaints when it comes to both wood and bamboo are moisture related.  The moisture is usually due to a site related condition.  Frequently a moisture problem is caused by conditions such as water under the structure, leaking pipe, excessively wet concrete or too much moisture in a buildings structural components at the time the floor is installed.  Improper maintenance also results in the introduction of excess moisture.

The major component in many cleaning chemicals is water.  Water can have a detrimental effect on both wood and bamboo floors which are hygroscopic materials.  When bamboo and wood are exposed to air their tendency is to either dry or gain in moisture.  The loss or gain in moisture will continue until the material is in equilibrium with the humidity and air temperature.  If too much moisture is gained these materials will swell and if too much moisture is lost they will shrink.  While bamboo is somewhat more stable then wood in this respect, both are affected.

Wood is dimensional stable at its saturation point of 25-30% moisture content.  Below this point it begins to shrink until it reaches 0%.  As it starts to gain in moisture it expands until it reaches the saturation point again.  Once back at the saturation point of 25-30% it again stabilizes.

When wood floors are manufactured it is kiln dried to an average of 6-9% Bamboo floors are usually kiln dried to 8-10%.  Both wood and bamboo when made into a floor are dried significantly below the saturation point.  Once at this point the flooring is expected to stabilize with the environment in which it is installed.  Since the floor still has a natural tendency to gain or loose moisture, it is imperative that the environment be maintained at a suitable level.

The expansion and contraction of floor material is not equal in all directions.  As an example, a solid piece of wood that was over dried to 0% and allowed to increase to its saturation point of 28%, will increase by about 0.1% longitudinally or along the length/grain.  The same piece of wood will increase 2 -8% perpendicular to the annular growth rings (racially or in strip width for flooring that is quarter sawn.  If the floor is plain sawn flooring the increase will be parallel to the trees annular growth rings (tangentially or in strip width.)  With engineered flooring the expansion will be significantly less.  The reason for this is that alternating layers of the laminate are prepared to run in opposite directions.  Since they are not all running in the same direction they have a natural tendency to pull against one another, which helps to maintain stability. While the engineered floor is more stable in this respect, equilibrium moisture content still remains critical.  The moisture content of wood and bamboo that is in storage or installed at a point below its fiber saturation point has a natural tendency to fluctuate.  This fluctuation is a result of changes in the relative humidity and air temperature within the environment in which the material is stored or installed.

An understanding of equilibrium moisture content (EMC) is important.  EMC is the point at which moisture is not being gained or lost.  Table 1 demonstrates the relationship between temperature and humidity and its resultant EMC.  Wood and bamboo will provide excellent performance for many years if properly maintained.  EMC is a major factor in its maintenance. 

Table 1: Moisture content of wood in equilibrium with stated dry-bulb temperature in Fahrenheit and relative humidity. *

Temp.Dry-bulb °F.	Relative Humidity (Percent)
	5	10	15	29	25	30	35	40	45	50	55	60	65		70	75	80	85	90	95	98
30	1.4	2.6	3.7	4.6	5.5	6.3	7.1	7.9	8.7	9.5	10.4	11.3		12.4	13.5	14.9	16.5	18.5	21.	24.3	26.9
40	1.4	2.6	3.7	4.6	5.5	6.3	7.1	7.9	8.7	9.5	10.4	11.3		12.3	13.5	14.9	16.5	18.5	21.	24.3	26.9
50	1.4	2.6	3.6	4.6	5.5	6.3	7.1	7.9	8.7	9.5	10.3	11.2		12.3	13.4	14.8	16.4	18.4	20.9	24.3	26.9
60	1.3	2.5	3.6	4.6	5.4	6.2	7.0	7.8	8.6	9.4	10.2	11.1		12.1	13.3	14.6	16.2	18.2	20.7	24.1	26.8
70	1.3	2.5	3.5	4.5	5.4	6.2	6.9	7.7	8.5	9.2	10.1	11.1		12.0	13.1	14.4	16.0	17.9	20.5	23.9	26.6
80	1.3	2.4	3.5	4.4	5.3	6.1	6.8	7.6	8.3	9.1	9.9	10.8		11.7	12.9	14.2	15.7	17.7	20.2	23.6	26.3
90	1.2	2.3	3.4	4.3	5.1	5.9	6.7	7.4	8.1	8.9	9.7	10.5		11.5	12.6	13.9	15.4	17.3	19.8	23.3	26.0
100	1.2	2.3	3.3	4.2	5.0	5.8	6.5	7.2	7.9	8.7	9.5	10.3		11.2	12.3	13.6	15.1	17.0	19.5	22.9	25.6

*From the Wood Handbook: Wood as an Engineering Material, 1999, the Forest Products laboratory, U.S. Department of Agriculture.

The equilibrium moisture content (EMC) is not the same for all locals.  Weather conditions, heat and humidity are not the same in all parts of the country.  Take a look at the Moisture Content Map (table 1).  Take a look at Oregon, the authors state and you will see 8-13 along the coast and 5-7 in the rest of the state.  What this map is telling you is that the normal point of EMC along the coast is 8% in January and 13% in July and inland it is 5% in January and 7% in July.  Now take a look at your own state and you may see and entirely different set of variables.

Moisture and humidity are changing throughout the day - throughout the year.  Additionally there are long-term seasonal changes in relative humidity and temperature.  Since wood and bamboo are hygroscopic material they are also experiencing continuing change throughout the day - throughout the year. 

In a dry climate and during the heating season wood and bamboo will shrink and this is normal.  Expansion is also normal in wetter climates and when exposed to wet conditions.  To maintain the floor at the proper EMC as exhibited in the tables; the environment needs to be carefully monitored. Wood and bamboo perform best in a controlled environment that has a relative humidity between 30-50% and room temperature of 60-80%.  These are the same levels that humans are most comfortable at.  In addition to temperature controls on a furnace, the use of a dehumidifier to remove moisture from the air or humidifier to add moisture to the air will be important in many parts of the country.

As stated earlier, engineered flooring (laminated flooring), due to its multiple layers that are glued together, will shrink and expand less than that of a solid floor. 

With an engineered wood floor the grain of each layer runs at a 90-degree angle to that of the adjacent layer, working against each other to maintain stability. 

Bamboo wants to bend and curl just like planks from a tree.  With an engineered bamboo floor the strips need to be directionally balanced.  On a 3-layer laminate, this is accomplished by arranging the strips so that on top and bottom layers the hard side is facing outward. Some manufacturers will randomly orient strips within the middle layer.  With bamboo, some manufacturers will have all of the layers running in the same direction and this is unacceptable.

While engineered wood products have a built in resistance to shrinkage and expansion and can be installed in areas with a wide ranges in humidity the EMC must still be controlled.

Bamboo the Environment and Giant Panda

Surfing the Internet, visiting homes and flooring stores one can become amazed at the large variety of floors that are available. Soft wood, hardwood, exotic wood and bamboo represent a few of our many floor types. Carpet, linoleum, sheet vinyl, laminate, ceramic and stone are a few more of the floors we enjoy. What a variety of floors and what a variety of environmental concerns. We argue over the spotted owl, endangered plants, endangered bugs and rodents. Oil spills at sea and pipeline breaks at land are far from a welcome to any of us. As necessary as mining may be, some of our most beautiful lands have been scarred by strip mining. Yes, these are all real concerns and all of us need to take them into consideration and weigh in our own minds how we truly feel about the products we choose to use.When we consider bamboo flooring and its effect on the environment it is important that we consider its effect on the giant panda. A panda must feed 12 to 16 hours a day, consuming 22 - 40 pounds of bamboo. When eating fresh shoots, each panda will consume about 84 pounds of bamboo shoots in a day. It is estimated that their are only 700 - 1500 giant pandas that exist in the wild. The giant panda is probably the best-known endangered animal. They compete with the farmers and are killed by the poachers. Bamboo is already being used for every other conceivable commodity from food, to housing, furniture, musical instruments, toys, tools, and just about anything else you can imagine. Here we are taking more bamboo away from the Panda to make floor covering, or are we?

In the Pacific Northwest they have environmentalist sitting at the top of trees in an attempt to keep them from being cut down. Some trees sitters are there for months and even a year or longer. Competitive priced wood is no longer available in the United States for housing, flooring, and furniture and just about everything else.

We need oil and lots of it for the day-to-day operation of our automobiles, houses, factories and the manufacturing of a multitude of products including floor covering. Most carpet, laminate and resilient is composed of oil-based products at least in part. Environmental concerns have made us dependant on foreign oil, from countries that have less stringent environmental regulations. And yes, oil prices continue to climb making most of our products more and more expensive.

Even those of us in the floor covering industry want a clean environment. We may be too busy to sit in a tree or block the construction of a pipeline, but when at the supermarket spending our hard earned cash, we still have to think fast when asked, paper or plastic? Do I want to cut a tree today or build a pipeline?

In China you do not have people sitting atop the bamboo canes. I imagine some would if they thought they could. Kidding aside, all of us need to be concerned with out environment and I truly believe those of us in the floor covering industry do care. Most all of us want to see the responsible use of our natural resources. We want the beauty of our country and our world to be here for future generations to enjoy.

So if less than a thousand Panda Bears survive in the wild, and rely on bamboo for their source of food, are bamboo floors the answer?

Nearly all of the bamboo flooring sold in North America is produced in the southern Chinese province of Hunan. This area is known as “the bamboo sea” for its extensive bamboo forests. The government owns the forest and individuals or companies can obtain contracts to harvest from them. Contrary to the concerns of many, the harvesting in these forests is not a threat to Pandas, as they live at much higher elevations and eat a different species of bamboo.

The habitat today of the giant panda is six small areas located in inland China. This habitat is suitable for the 15 or so bamboo varieties on which the panda survives. The area is a cold, damp coniferous forest with elevations that range from 4,000 to 11,000 feet.

More than 1,000 species of bamboo are found worldwide. The Moso species (phyllostachys pubescens) is a popular species for flooring. The Moso grows to about fifty feet in height and two feet in circumference. Moso is primarily found in the low mountain areas of Zhejiang province (It is in the Temperate Zone about 30 degrees North latitude). The temperatures in this area range from below freezing in the winter to over 100 F in the summer.

Mao Zhu (hairy bamboo) is another popular bamboo used for flooring. It is one of the hundreds of bamboo species not consumed by panda.

With its rapid growth cycle and abundance, bamboo floors really do appear to be environmental friendly.

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