PROBLEMS, CAUSES and CURES of HARDWOOD FLOORS 2Nd Edition

NATIONAL WOOD FLOORING ASSOCIATION TECHNICAL PUBLICATION No. C200

Price: $30

PROBLEMS, CAUSES AND CURES OF HARDWOOD FLOORS 2nd Edition

INTRODUCTION Shellout/Dishout of Springwood 3 How to inspect a floor Slivers/Splinters Tools for inspection Squeaky/Loose Floors (“Popping”) Determine the problem Sticker/Stick Stain Find the cause Unevenness of Entire Floor Questions for the consumer Questions about the history of the FINISH PROBLEMS job site 14 Applicator Streaks Questions about the job site at the Bleed Back time of inspection Bubbles Questions about the home’s exterior Chipping Questions about the history of the Cloudy Finish wood flooring Cratering JOB-SITE PROBLEMS Crawling 6 Buckling Discoloration Chatter/Wave Marks Early Finish Wear Checks Fish Eyes Compression Set Orange Peel Crowning Peeling Cupping Pin Holes Delamination Poly Beads Dents Roughness/Grain Raise Dish Out Sidebonding Endlifting Stains Face-Checking Sticky Board Syndrome Flooded Floors Tannic Acid Discoloration/Pull/ Bleeding Gaps, Normal Uneven Sheen Levels Gaps, Abnormal Wrinkling Grade Problems Greenhouse Effect INDEX Insects 21 Overwood/Underwood SOURCES AND CREDITS Panelization 22 Picture Framing (“Halo”) Sanding Marks RESOURCES Shake 23

NO GUARANTEE OR WARRANTY The information contained in this publication represents widely accepted industry practices. There are, however, no universally approved methods of troubleshooting wood floors. The National Wood Flooring Association accepts no risk or liability for application of the information contained in this publication.

INTRODUCTION widths of strips, etc. • POCKET KNIFE OR DEPTH GAUGE: can be inserted n a perfect world, this technical manual between boards to determine the wear layer depth. wouldn’t be necessary. Every wood flooring • FLASHLIGHT: to look in crawlspaces. Also can installation would be flawless, every con- be used to throw shadows to determine if a single Itractor would get paid, and every customer strip is moving up and down. would be happy. Of course, that is not the case. • EARTH MAGNETS: to locate flooring cleats or staples. Many variables go into the installation, sand- • HAMMER: to drive in moisture meter probes and ing and finishing of hardwood floors. Sometimes aid in removing flooring samples. things go wrong, and sometimes there are pre- • BLADE AND PHILLIPS SCREWDRIVERS: to scrape existing problems with a job site that could not and pry with; also useful for working on moisture be detected at the time the floor was installed or meters. sanded and finished (flooring contractors are not • THIN “FEELER GAUGE” OR TAPER GAUGE: both responsible for such pre-existing problems). are used to measure the width of gaps. The taper Even when there is a problem, the floor doesn’t gauge is easier to use. have to be a failure. If the cause can be pinpoint- • NOTEPAD AND PEN/PENCIL: to record data. ed and corrected in a timely, professional manner, • MICROMETER: to measure the width of the ma- the contractor still can have a satisfied customer. terials for comparison to original manufactured width. • CAMERA (DIGITAL PREFERRED): to create a vi- HOW TO INSPECT A FLOOR sual record of observations. Inspection of wood floors should be done from • THERMOMETER: for checking surface tempera- a standing position (5 feet up and 2 feet away) ture. Electronic hygrometers also may do this. with normal lighting. Glare, particularly from • STRING (ABOUT 15 FEET): can be pulled taut large windows and flood lighting, magnifies any across boards to determine if the floor is flat. irregularity in the floors and should not deter- • LIT MAGNIFYING GLASS: Commonly available at mine acceptability. electronics stores, this is useful for seeing scratch Just as no two floors are the same, the inspec- patterns and debris on the floor. tion process varies for each floor problem. How- ever, there are two basic goals every time you go to inspect a floor: DETERMINE THE PROBLEM 1 - DETERMINE WHAT THE PROBLEM IS. The first step in the inspection is talking to the 2 - FIND THE CAUSE OF THE PROBLEM. client to discover exactly what he or she is un- Sometimes it may be necessary to remove and happy about. Sometimes floors that are a “prob- replace a limited number of flooring boards dur- lem” to the customer are well within industry ing the inspection. standards. Such situations often are a case of misunderstood customer expectations. Although handling complaints from unhappy TOOLS FOR INSPECTION clients probably is your least favorite aspect of • MOISTURE METER(S): (for wood and concrete): being a wood flooring contractor, there are steps to get an average reading of the flooring moisture you can take to minimize the grief involved, espe- content percentage, and also to get an average cially when customers are really angry. Here are reading at various levels through the wood floor some things to keep in mind when meeting with and subfloor (for the latter, moisture meters with the unhappy client: 1 1 ⁄8-inch pins are commonly used). • LISTEN. Except for the few “professional com- • ELECTRONIC HYGROMETER/THERMOMETER: to plainers” who use complaints to avoid contractual measure temperature, relative humidity and dew obligations, most clients first need to vent their point. frustration—and you need to know the problem. • TAPE MEASURE: to measure distances, aggregate So, listen all the way through customers’ re-

marks, even if they become offensive. Clients may the house/building? feel that to get some attention, they must shout • How do you maintain the building environment? at somebody. Let that happen. Afterwards, they probably will be easier to deal with. • Are windows open during the year? For how long? • BE SYMPATHETIC. Never take a complaint per- • Do you live in the space year round, or is this a va- sonally—not even a tirade. You can express your cation home that is closed up for part of the year? concern without taking sides, even if you later • How do you clean the floor? What products are must dispute much of the customer’s view of the used in flooring maintenance? problem. You can’t blame the owners for wanting the problem fixed. • When did you notice the problem? • BE OBJECTIVE. Do not allow emotions or prior • Where did the problem start? knowledge to get in the way of handling facts • How did the problem progress? as facts. Just collect all the facts. By the same token, keep in mind that a few boards do not • Has the problem worsened since you first noticed always make a legitimate complaint. it? Stayed the same? • LOG ALL INFORMATION. Keep written records • Has any action been taken to correct the prob- throughout the project, from the first contact lem? What has been done? through a full inspection. Initially, get all perti- nent data such as owner’s name, address and phone, plus the same information on the builder, Questions about the history of the job site: retailer or contractor; what the product is; brand; • When did job site construction begin? when purchased; quantity, when installed and • When were the foundation and framing con- when finished. And get a full description of the structed? When was the roof in place? When were problem at the outset. the windows and doors in place? • INSPECT THE FLOOR AS SOON AS POSSIBLE. De- • If over a crawl space, was the earth covered with lays can create a second complaint and do little 6- to 8-mil polyfilm, and if so, when? for your credibility. Do not make a snap judgment of the problem and, above all, do not report your • If over a slab, what is the underfloor and sub- findings on the spot to the client, builder, or any floor set-up from the slab to the flooring? Is a other interested party. vapor retarder in place between the concrete slab and the subfloor? What is the vapor retarder? • Was the subfloor exposed to adverse weather FIND THE CAUSE conditions prior to the roof, windows and doors Once you have defined what the problem is, it’s being installed? time to do the detective work and determine why • When was the HVAC system installed? When the problem happened (or still is happening). was it turned on? Sometimes this is cut-and-dried—such as when • When were the masonry, concrete, drywall, and you see a big footprint in the topcoat. More often, other wet-work installed and dried? rooting out the cause takes more investigation. The following is a detailed list of standard things to consider when inspecting a floor. Of course, not Questions about the job site at time of the all details are necessary for every inspection, but inspection: they all are possible factors in a problem floor. If • What is the subfloor? Is it concrete slab or over you’re the one who installed the floor, the trouble- joists? If it’s over wood joists, what is the thick- shooting may be easier. If you’re trying to follow up ness of the subfloor? Is the subfloor approved for on someone else’s failed floor, it may take a more wood flooring application? detailed investigation. • Are there screeds? Many of the following questions relate to the • What are the floor joist or truss materials? What most common culprit when dealing with wood is the spacing of the floor joists or trusses? Are flooring problems—moisture. For further infor- they close enough together to support a flat floor? mation on moisture and wood flooring, refer to (For recommended joist or truss spacing, see the NWFA’s Technical Publication No. A100: Water NWFA Installation Guidelines.) and Wood. • In a crawl space, is the square footage of the pe- Questions for the client: rimeter vents through the foundation equal to 1.5 • When did you occupy the house/building? percent of the square footage of the area within the crawl space? Are vents open to allow proper cross • When was the HVAC system made operational? ventilation? Is the relative humidity in the crawl • Does the HVAC system operate year round? space no higher than it is in the house interior? • Do you monitor or control the humidity level of • Is the soil within the crawl space properly cov-

4 © 2011 NATIONAL WOOD FLOORING ASSOCIATION NATIONAL WOOD FLOORING ASSOCIATION TECHNICAL PUBLICATION No. C200 ered with 6- to 8-mil black polyfilm or equivalent? Questions about the history of the wood • Is there a 6-mil polyfilm or equivalent moisture flooring: retarder beneath the slab? • Who manufactured the products (wood flooring, finish, adhesive, etc.)? • What is the moisture content of the subfloor and what is the relative humidity of the job site? (Ide- • When were the products manufactured? ally, relative humidity should be between 30-50 • Does the manufacturer have records of the wood percent, although it may vary according to geo- flooring moisture content at time of shipment? graphic region.) • When was the wood flooring delivered to the dis- • Is the concrete slab’s moisture level suitable for tributor warehouse? installation? How old is the concrete slab? In a • Was the wood flooring unloaded in a covered new building, it must be at least 30 days old be- warehouse? fore you can consider moisture testing. • Was the wood flooring completely covered and • Are all major appliances and systems properly protected on the truck at time of arrival? vented to release warm, moist air? Visually inspect plumbing in the area where the floor is installed. • Did the distributor check the moisture content, grade, and appearance of the wood flooring at time • Is there a sense of damp, moist or stagnant air of delivery? when entering the home? Check the interior with a hygrometer. Are the heating and air conditioning • When was the wood flooring delivered to the job systems operational? Ideally, temperatures of the site? Was it in an enclosed delivery truck and pro- subfloor, adhesives and flooring should be over 60 tected during transfer to the job site? degrees Fahrenheit during installation. • What were the weather conditions when the • Are the HVAC systems in place and working? wood flooring was unloaded at the job site? The intent is for flooring be be installed as close to • What were the job-site conditions at time of delivery? normal living conditions as possible. • At time of delivery to the job site, what was the • What type of heating is it? Radiant, baseboard, moisture content and overall condition, grade and radiator, forced air (electric or gas)? (Baseboard appearance of the flooring? or radiator heat may overdry adjoining flooring; • Where was the wood flooring placed at the job radiant heat may cause problems if the correct site? Did it remain there until it was installed? procedures were not followed for wood flooring installation.) • Was the flooring acclimated correctly? • Is the heating system equipped with a humidifier? • Was the wood flooring completely unwrapped/ unpacked at time of delivery? Questions about the home’s exterior: • When did flooring installation begin and end? • Check the eave overhang on the building. Is all • At time of installation, was the job site at or near rain water funnelled away from the foundation? normal living conditions? What were the environmental conditions of the job site? • Check the gutters and downspouts. Is all rain water properly diverted away from the foundation? • At time of installation, what were the moisture During a rain, the depressions below the spouts can content and conditions/appearance of the flooring fill with water that eventually finds its way indoors. and the subflooring? • Are there raised flower beds or planter boxes • Where did flooring installation begin and how did adjoining the building’s foundation? If so, a special it proceed through the house? moisture membrane should be installed. Are land- • What are the fasteners? How far apart are they? scape sprinklers directed away from the house? Were the tools pneumatic or manual? • Is there an outdoor pool or body of water elevat- • What kind of adhesive was used? Was the correct ed above the home’s foundation that could over- spread rate followed? Was the right trowel used? flow or leak into the home’s foundation? • Is there a moisture retarder between the subfloor • What is the lot’s relationship to the street, to the and flooring? What is it? neighboring site, to a nearby hillside, to a nearby pool? The site should be properly graded to divert • Where did sanding and finishing of the flooring water away from the foundation. begin and end? • Does the driveway slope away from the house? • What is the finish? How was it applied? What was the sanding sequence and finishing process? • Are the roof, windows and doors all in place and weather-stripped? • When was the job site occupied? • Has any action been taken to correct the problem? What has been done?

or have compressed rubber. Also, BUCKLING - Poor splice/seams on the abrasive belt, drive What it is: belts and fan belts Excessive expansion - Running the big machine in the wrong direction causing the wood - Bad bearings in the fan housing. flooring to release • Most wave marks are caused by imperfections from the subfloor. already present on the floor that are transferred through the wheels of the big machine to the Cause: sanding job. • Moisture caused by: • Wheels on the big machine that are out of - Excessive job-site round or dirty. moisture (airborne, • Improper electrical hookup—voltage that is too subfloor or flooding). high or low. - A house left vacant • Undulation of the floor from joist truss deflection. with no HVAC operating or inadequate HVAC (“greenhouse effect”). Cure: - Grade conditions. First, the problem with the big machine must be - Pipe leaks. determined and fixed. Then, use a hard plate, - A wet slab. paper disc or multi-disc sander. A sanding screen - Excessive humidity. only highlights the chatter and causes the floor to Excessive moisture is always the main cause of dish out. Use a disc sander and hard plate while buckling. Factors that may aggravate the problem working right to left, traveling down and back in include these improper installation techniques: the same path and working the disc sander at • For nail down products, inadequate nailing, in- slight angles for the best cut of the unit. Repeat correct fasteners, incorrect subfloor construction. the same procedure, overlapping the last cut one- • For glue-down products, incorrect adhesive, half the size of the first disc. insufficient adhesive, the wrong trowel used, Another technique is to do a light sanding with inadequate adhesive transfer, subfloor separa- the big machine at a 7-15 degree angle, then go tion, improper subfloor preparation or subfloor over the floor again, this time straight. contamination. If using a multi-disc sander, walk slowly with • Inadequate expansion space. the grain from side to side, always overlapping the unit as you move from right to left. This Cure: blends in the floor and prevents deep scratches. Fix the high-moisture condition (including the If joist design or loose flooring is the problem, use of dehumidifiers) and allow the floor and the structural flaws must be corrected before the subfloor to dry to normal levels. Release stress on floor is resanded and refinished. the floor by providing relief at all vertical obstruc- tions (walls, cabinets, etc.) and possibly removing a row of flooring. If caught early, spot repair/ CHECKS replacement may be possible. In many cases, complete replacement is necessary. What it is: Separations of the wood that normally occur across or through CHATTER/WAVE MARKS the annual rings. What it is: Chatter marks are consistent sanding imperfec- Cause: 1 tions across the grain of the wood varying from ⁄4 • Loss of moisture inch to 1 inch apart. Wave marks are two or more due to drying pro- irregularities in a floor occurring along the direc- cesses during manu- tion of travel of a sander. They generally are 1 to facturing, or environ- 3 inches from peak to peak. mental conditions during storage or after installation. Cause: • Most chatter marks are caused by the sand- Cure: ing drum. It may be out of balance, out of round, Board replacement, with a recoat if necessary. have hard spots, have incorrect paper installation

• Excessive drying from below can cause a mois- COMPRESSION-SET ture imbalance that causes crowning. What it is: Boards being subjected to a substantial increase Cure: in moisture while being restrained from swell- First, determine if the moisture content in the ing by adjacent boards, resulting in a permanent subfloor and floor has stabilized and returned to narrowing of the boards due to the edges of the normal levels, and if all of the crowning from the boards being crushed. The gaps often begin original cupped condition has occurred. After the to darken with age and the edges may become floor has stabilized, resand and finish. slightly lifted and splintered. The compression is often exaggerated by debris becoming embedded in the gaps between boards. It is normally as- CUPPING sociated with flooring that has been installed for more than one year. What it is: Cupping occurs Cause: across the width of Any exposure to a substantial increase in mois- the individual pieces ture causing excessive expansion, which is fol- of flooring. The edges lowed by lower moisture levels and contraction are high and the that makes the gaps between boards apparent. center is lower. It Some examples of excessive moisture include: generally develops • Water leaks, such as those under a plant, by gradually. refrigerator icemakers and by dishwashers. • Flooded floors. Cause: • Excessive surface moisture during mainte- • A moisture differ- nance. ential within individual pieces of flooring, usually • Floors with high moisture content created by excessive moisture on the underside of the floor- high relative humidity. ing. More subtle cupping can be caused by lack Note that the look of a compression-set floor may of proper acclimation (this is generally permanent be similar to gaps from other causes, such as floor- cupping). Potential sources of excessive moisture ing that was milled and installed with a high mois- include: ture content. When they are at the same moisture - Building leaks content at which they were milled, compression-set - Poor drainage boards will be narrower than the milled width. - Plumbing leaks or overflows - Leaks from dishwashers or refrigerator ice- Cure: making units Correct the source of the high moisture and fol- - Wet or damp basements/crawlspaces low proper maintenance procedures. Fill gaps as - Concrete subfloors that have not cured necessary and sand, fill and refinish the floor if - Plywood subfloors with excessive moisture necessary. In some cases, some boards (or, occa- - Poor or no ventilation sionally, the whole floor) may need to be replaced. - HVAC system not operating. • Solid flooring also may cup when a wood floor experiences conditions that cause rapid drying on the surface. This condition occurs with gaps as CROWNING the flooring shrinks. What it is: • Low humidity levels can cause cupping in engi- The center of the neered flooring that is usually referred to as “dry pieces of flooring cupping.” With dry cupping, the wood in the top appears to be higher layer attempts to shrink across its face while the than the edges. shrinkage of the plywood backer is considerably less. (Dry cupping is also often accompanied by Cause: “face-checking”—cracks in the board faces; see • While it is pos- page 9.) sible that excessive moisture could cause Cure: crowning, it is more Never attempt to repair a cupped floor until all likely that the floor of the sources of excessive moisture have been previously cupped and was sanded before the located and eliminated. This can be verified only moisture content returned to normal. Sanding too with a moisture meter that takes readings of the soon removed the raised edges. When the boards underlying subfloor. As long as the wood is not eventually dried, their edges were lower than the permanently deformed or damaged, the flooring center.

will return to its original shape and size when the excessive moisture is removed. This may take DENTS weeks, months, or even an entire heating season. What it is: Attempting to sand a cupped floor while it A crushed spot in the is still too wet may cause subsequent crown- wood. ing when the floor dries. Flooring that does not return to its original shape, even after complet- Cause: ing an entire heating season, probably is perma- • High heels. nently deformed. (Taking moisture readings at • Dropped heavy different levels in the wood flooring also can help objects. determine this—if there is a difference of 1 per- • Metal tips on furni- cent or more between the top and bottom of the ture legs. boards, they probably are not done drying.) If the • Shipping damage. boards are permanently deformed, the cupped edges may be sanded off. Cure: For floors that have cupped due to drying, Remove and repair the damaged boards. The en- relative humidity should be increased. Relative tire floor may need to be resanded and refinished. humidity below 20 percent is considered very dry Institute good floor maintenance procedures, for wood flooring, and it is suggested that humid- such as removing high heels and using floor ification be provided under such conditions. protectors.

DELAMINATION DISH OUT What it is: What it is: The separation of a Areas on the wood layer from an adjoin- floor where softer ing one within a piece parts of the wood of engineered wood appear to have been flooring. sanded or hollowed out more than other Cause: areas. It is more evi- • When it happens on dent in wood species the job site: flooding that exhibit pro- or other excessive nounced spring (soft) moisture, or humidity and summer (hard) that fluctuates between extremes. grain patterns (see also “Shellout/Dishing of • Manufacturing error (when there is minimal or Springwood” on page 12) or between mixed spe- no wood tissue attached to adjoining layers due cies of varying hardness together on a floor, such to lack of glue). as in feature strips, borders and medallions.

Cure: Cause: Replace the affected boards. In most cases, the • Using the wrong angles while sanding with the delamination will affect only a small number of big machine. boards—not the entire floor. • Using a too-flexible pad on the buffer during the screening process.

Cure: Resand the floor using a slight angle with the big machine; do not cross borders at a right angle. A hard plate or multi-disc sander may be needed.

ENDLIFTING FLOODED FLOORS What it is: What it is: Ends of engineered Standing water on the wood floor. wood flooring boards appear raised. Cure: Remove the source of the water intrusion and Cause: dry the floor as quickly as possible. Elevate the • Too much moisture temperature, dehumidify and increase air flow during installation. using fans. In basement houses, dry from below. • improper spacing of In crawlspace homes, use exhaust fans. staples/cleats. Do not repair the floor until moisture meter • Adhesive not drying readings on the top and bottom of the boards and due to excessive slab subfloor are at normal levels. When flooring is moisture. stabilized, determine the damage. If the floor- • Wrong adhesive or trowel. ing has loosened from the subfloor, repair the • Manufacturing error. necessary areas or the entire floor. If it is cupped, • Improper maintenance. sand it flat. If the floor is flat, fill if necessary and abrade/screen and recoat. Cure: If the subfloor is plywood over concrete, it is Before any cure happens, any problems related unlikely that the plywood and concrete subfloor to excessive moisture must be resolved and then will dry out in a reasonable time. Full removal to affected areas repaired. For endlifting caused concrete usually is best to allow the slab to dry. by improper staple/cleat spacing or the wrong In some cases partial or full removal of the fin- adhesive or trowel, the affected areas must be ish may accelerate the dry time. repaired. In cases where you have determined that the flooring system has not returned to normal levels, do not succumb to pressure from involved parties FACE-CHECKING for a quick fix. What it is: Long cracks in the veneer that run along GAPS, ABNORMAL the length of the What it is: board in engineered Gaps in the floor flooring. that remain with seasonal change. If Cause: some boards appear • It typically occurs glued together by the when flooring is man- finish on the surface, ufactured with a MC see “Sidebonding” on incompatible with the page 18. environmental conditions where it is installed. Cause: Cure: • Edge crush/com- Correct the humidity levels and follow proper pression set from prior exposure to extreme mois- maintenance procedures. Fill gaps as necessary ture (especially for solid, flat-grained flooring). and sand, fill and refinish the floor if necessary • Hot spots in the subfloor, such as poorly insu- (this may not always restore the original appear- lated heating ducts, hot water plumbing lines, ance of the floor). In some cases, some boards radiant heating systems, register openings and (or, occasionally, the whole floor) may need to be appliance motors. replaced. • Debris between boards during installation. • Improper nailing/nail position. • Cracked tongues. • Flooring installed with an excessively high moisture content or over a subfloor with excessive moisture. • Flooring not installed tightly together to begin with. • Foundation settlement or subfloor movement. • Improper subfloor materials that will not hold nails.

• For glue-down floors, early foot traffic, incorrect adhesive, the wrong amount of adhesive trans- GREENHOUSE EFFECT ferred or used, the wrong amount of flash time for What it is: the adhesive, or not using a roller when recom- Floors that shrink or swell due to limited air mended. movement and inconsistent humidity levels.

Cure: Cause: Eliminate the cause, then restore normal humid- Buildings closed up with no air control or air ex- ity levels. After the floor has stabilized, use filler change. Sunlight through windows can generate in gaps that are small enough to be filled (typical- heat, creating condensation and abnormal hu- 3 midity levels. Noticeable shrinkage or expansion ly up to ⁄32 inch) and recoat the floor. For larger gaps, use a sliver/“Dutchman” or wider board to will occur when an attempt is made to stabilize fill in the gap. the atmosphere.

Cure: GAPS, NORMAL After the environment becomes stable, follow cures discussed for cupping floors, buckling or What it is: gaps. Controlling the atmosphere during and Gaps that appear between individual boards and after the installation is critical to avoid issues open and close with changes in humidity. caused by the greenhouse effect. Cause: • Most normal gaps are caused by seasonal fluctuations in relative humidity—the floor expands INSECTS with high humidity and contracts during periods What it is: of low humidity. This type of expansion and con- A sagging surface traction is considered to be normal and expected or small fresh holes for wood floors. Wider boards have even wider surrounded by a halo gaps. of fine dust or small • Square-edged floors show gaps more than bev- holes appearing in eled floors, and light-colored floors show gaps the surface of the more than dark floors. flooring.

Cure: Cause: Normal gaps can be minimized by using the • If the surface of the HVAC system to control fluctuations in humid- flooring is sagging, it ity in the building. The use of humidifiers and/ is likely that termites have created eating cor- or dehumidifiers can narrow the overall range of ridors beneath the surface. Termites are white or humidity fluctuation. cream-colored. • If fresh holes, often surrounded by a light- 1 colored powder, about ⁄16-inch wide are found, GRADE PROBLEMS powderpost (lyctid) beetles are probably the cause. • Small holes that are present at the time of What it is: installation or appear at a later date may be evi- Unhappiness with the floor due to the appearance dence of pin worms, which are often misidentified (i.e., knots, grain pattern, color variation, etc.) as powderpost beetles.

Cause: Cure: • Unrealistic customer expectations. Almost all wood flooring is kiln-dried, and proper • Ordering mistake by supplier, distributor or kiln-drying will kill any insects and larvae in installer. the wood. However, new material quickly may • Poor grading at the mill. become infested by insects entering through • Improperly labeled product. windows, in firewood, etc., and the life cycle from eggs to live insects is very short. Also, check all Cure: surroundings for infested wood molding and fur- Replacing the offensive boards may be necessary. niture (especially bamboo, mesquite and ash). (See Technical Manual A500: Grading and Packag- For termites, a professional exterminator ing) should eliminate the insects. Then, structural damage should be repaired. Damaged floorboards should be pulled and replaced. Termite infesta- tion is not related to wood flooring manufacturing or installation; it is a site-specific condition.

For powderpost beetles, determine the extent of the contamination, and remove and replace PANELIZATION boards as necessary. Or, if only a few holes are What it is: found, fill them. If further evidence of insect con- A generally uniform appearance of gaps in the tamination occurs at a later date, follow the in- surfaces of the floor that represents the size of structions above. Note that holes appearing in the the subfloor panel beneath it. surface of the wood surrounded by a thin halo of powder (frass) indicate the end of a life cycle—the Cause: insect has bored out of the wood to fly and mate. Excessive movement, shrinkage or expansion of Filling the hole may prevent recurrence, as the subfloor panels. insect, once mated, will not be able to return to the bore hole to lay eggs. Powder post beetles do Cure: not mate and repopulate in the wood, and their Issues related to the subfloor must be resolved; life cycle is fairly short—generally 3 to 6 months. typically this is not the responsibility of the floor- All oak flooring grades allow the presence of ing contractor. Then, repair the wood floor as pinworm holes in the face of flooring strips. When necessary. flooring containing the pinworm holes is sanded and finished, sanding dust and/or filler sift into the holes. As the finish is applied, a film is PICTURE FRAMING (“HALO”) formed over the holes. With wear, the film breaks What it is: and the pinworm holes are revealed. They often The edges of the room are about the size of powderpost beetle emer- appear to be a slightly gence holes and sometimes are mistaken for real different color than infestations. Pinworms only occur in the living the rest of the room. tree, and they can typically be identified by ex- amining the hole with a magnifying glass for the Cause: presence of finish and filler within the hole. • Sanding the edges of a room with an improper grit sequence OVERWOOD/UNDERWOOD relative to the field. What it is: The edges are then A difference in height between boards. either smoother or rougher than the center of the floor, causing the finish and/or stain to appear Cause: different. • Insufficient subfloor holding power. • Applying more finish around the floor’s perimeter • Irregular subfloor. than in the field can sometimes cause a picture- • Incorrect nailing schedule or the wrong frame appearance. fasteners. • Tongue fracture. Cure: • The wrong type of adhesive, trowel and/or Resand the floor, being sure to use the proper grit spread rate. sequence on all parts of the floor. • Improper manufacturing.

Cure: For factory-finished flooring, correct the problem, then replace the affected boards. For unfinished flooring, correct the problem, then resand the floor if necessary.

SANDING MARKS SHAKE What it is: What it is: Sanding imper- Separation or weakness of wood’s fiber bond fections seen as between or through its annual rings. Shake is scratches, drum often confused with checks parallel to the face (as marks, dishouts, happen in quartersawn and riftsawn boards) or sanding scratches, raised grain. swirl marks and stop marks. Cause: Shake is usually considered to be naturally oc- Cause: curring in the tree. Changes in environmental • Problems with the humidity can make shake visible when it was not big machine. visible at the time of installation. • Drum out of balance. Cure: • Drum out of round. Shake should not be installed if visible at time • Hard spots on the of installation. If boards with shake appear in drum. the floor, it may be possible to repair the boards • Incorrect paper using low viscosity, CA (cyanoacrylate) adhesive. installation. Apply the adhesive under the seam of the shake. • Running the ma- The adhesive will wick down and hold the shake. chine in the wrong Or, the boards may need to be removed and direction. replaced. • Worn pulleys. • Bad bearings in the fan housing. SHELLOUT/DISHING OF • Wheels out of round and/or dirty. • Improper electrical hook-up. SPRINGWOOD • Poor splice/seams on the abrasive. What it is: • Damage to the abrasive. Uneven wear between • Poor workmanship. segments of annual • Dirt or grit on the buffer’s abrasive. rings. (For “Dishout,” • Using an abrasive that is too aggressive on the see page 8) buffer. Cause: Cure: • Heavy traffic. If the problem is with any equipment, it must • Repeated sliding of be determined and fixed. Check the abrasive for heavy furniture. any imperfections. Hand-scraping to remove very • Water used in deep scratches, drum or stop marks may be nec- maintenance. essary. Another technique is to do a light sanding • Seen especially in peeled-face engineered prod- with the big machine in the affected areas at a ucts under desks with heavy foot and caster wear. 7-15 degree angle, then go over the floor again, this time straight. Cure: If using a multi-disc sander, walk slowly with Sand and refinish, then implement better mainte- the grain side to side, always overlapping the unit nance practices. Change casters to wide, non- as you move from right to left. This blends in the marking rubber if necessary. floors and prevents deep scratches.

SLIVERS/SPLINTERS STICKER/STICK STAIN What it is: What it is: Slivers and/or splinters protrude from the surface of Light brown marks the floor, especially at the edges of the boards. that appear on the wood flooring surface. Cause: They occur across • Unevenness caused by expansion, cupping, edge the width of the strip, 3 crush/compression set from expansion, grain measure ⁄4 to 1 inch raise from moisture or subfloor irregularities. wide and occur about • Damage during installation. every 12 to 24 inches • Shake (see “Shake” on page 12). across the face of • May tend to occur more frequently with beveled the floor. (In photo prefinished products and wirebrushed products. shown, right side of • Improper grading. the strip is coated with oil-modified finish; left side is unfinished.) Cure: If a floor is producing rough/raised fibers, not Cause: splinters, buff vigorously with a commercial buf- • Discoloration of the rough sawn lumber while fer and tampico/soft brush attachment. air drying or being kiln-dried on stacking sticks For slivers along the sides or edges, shave off before being made into flooring. with a razor knife, then re-stain and putty as necessary. Cure: For expansion, cupping and grain raise, cor- Sticker stain is allowed in some grades. Sticker rect the moisture source, then wait for flooring to stain generally does not sand out. stabilize before making final repairs. . UNEVENNESS OF ENTIRE FLOOR What it is: SQUEAKY/LOOSE FLOORS The entire floor as a unit appears to be uneven. (“POPPING”) Cause: What it is: • In a wood joist system, causes include warped Objectionable squeaks or other noises. and loose subfloors, joists that are warped or Cause: fractured, settled support pillars, foundation settlement or installing flooring parallel to joists. • Movement of the wood flooring system, subfloor • In a concrete slab system, a cracked and/or system or underfloor supports. settled slab. • Improper joist spacing. • Uneven subfloor. • Inadequate or improper nailing. • Flooring installed over uneven screeds. • Weak subfloor. • Improper subfloor materials (thickness and/ Cure: or type). Structural integrity of the subfloor system is not • Insufficient or incorrect adhesive. the responsibility of a wood flooring contractor • Floor subjected to excessive moisture or exces- unless he or she installed the subfloor system. sively dry conditions. However, wood flooring contractors should check • Mismilled flooring. the floor for flatness before beginning an instal- • Old age of the floor. lation, and the party responsible for the subfloor Cure: installation should make necessary repairs prior to wood flooring installation. Noises in only certain areas may be fixed by in- jecting adhesive into the problem area, screwing the floor down from below, or strengthening the subfloor from below. For floors that are noisy and loose throughout, the cause must be identified and resolved.

lthough many problems can result with finish, the source is not necessarily the BLEED BACK A finish itself. Consult the following list for What it is: some of the most common problems and solu- Bleed back of oil- tions. If you have questions not covered here, based stain occurs members can call the NWFA’s technical hotline when excess stain at 800/422-4556 or 636/519-9663 (local and seeps up after it has international). been applied on open grain or from the gaps between boards.

APPLICATOR STREAKS Cause: What it is: • Excessive stain ap- After the floor dries, plication. marks still are vis- • High-viscosity or highly pigmented stain. ible from the path • Excessive heat during drying. of the applicator. It • Knots or burl areas. usually is associated more with water- Cure: based finishes If bleed back occurs before the finish is applied, than other types of wipe off the excess stain or burnish/buff the floor finishes, although it with a white pad to remove the excess and even may affect all other out the stain color. Then, let the stain dry thor- finish types, as well. oughly before applying another coat. If finish already has been applied over bleed Cause: back, a complete resand is often required. • Using an applicator that has hardened spots Trowel filling a floor may help reduce the poten- in the fibers. tial for bleed back from very grainy wood. Cover • Finish not applied evenly, with inconsistent windows during application to prevent hot spots finish thickness. on the floor. Make sure that stain is not left to • Excessive air movement and abnormally high puddle for a long time on a floor before it is wiped temperatures causing the finish to dry too off. quickly, resulting in a wet edge of finish being pulled over one that has already started to dry. • Applying a satin or semi-gloss finish that has not been stirred properly, resulting in flatten- BUBBLES ing agents leaving dull streaks when they are What it is: spread out. Dried bubbles are • Applying finish in directly sunlit areas that are visible on the surface too hot to be coated successfully. of a finish. • Areas where direct airflow dries the finish faster than on the remainder of the floor (for Cause: example, in front of heating registers or directly • Overworking finish in front of a refrigerator, where warm air blows during application. over the finish). • Too much air movement across the floor, Cure: drying bubbles into Abrade/screen and recoat under favorable ap- place before they plication conditions after the finish has dried have a chance to pop and flow out. sufficiently. Follow the finish manufacturers’ • Applying finish to a floor that is too warm, re- directions. sulting in the finish drying too fast. • Floor not being abraded/screened or sufficiently cleaned between coats of finish. • Using an improper applicator.

Cure: appears clear when it is dampened with water or Problems in the top finish coat can be abraded/ solvent, the problem can be fixed with an abrade/ screened and recoated. Cover windows during ap- screen and recoat (the cloudy/milky appearance plication to prevent hot spots on the floor. Do not will appear again when the spot dries). Be sure overwork the finish you are applying and reduce to do this when the application conditions are excessive airflow over the floor. Select an appli- favorable. cator that is less likely to induce excessive foam However, when the cloudy/whitish appearance formation; check with the manufacturer for the does not disappear upon wetting the substrate, recommended applicator. the problem is throughout the coating film and requires removal of the existing finish and application of a new finish to restore the appearance. CHIPPING What it is: Dried finish separates CRATERING from the surface in What it is: the form of flakes or The formation of chips. small bowl-shaped depressions in the Cause: finish. • Applying a less elastic finish on top Cause: of a more elastic one. • Contamination of • Improper adhesion the floor or finish. between coats. • Spot contamination. Cure: • Incomplete/insufficient abrasion between finish Sand the problem coats. areas by hand-sanding or using a small electric • For factory-finished products, edge chips may random orbital sander, and then abrade and be caused by rough handling, hitting edges with recoat. Often, hand-sanding out craters will installation tools or excessive finish on the edge. leave an unevenness/dip in the finish on the floor. To eliminate low spots, spot finishing the Cure: areas may be necessary before the entire floor is If the chipping is in an isolated area, spot-repair recoated (this will also prove if the fix takes care may be possible. When the chipping is wide- of the contamination problem). If the problem is spread, a sand and refinish may be required. widespread, the floor may need to be completely For factory-finished products, individual board resanded. replacement is an option. If it is determined that the problem is caused by contaminants between the boards, trowel- filling the floor may help prevent problems. When CLOUDY FINISH you suspect that there is a chance of contamination on the floor, make sure you first clean the What it is: floor thoroughly before attempting to abrade and The finish appears cloudy or milky. refinish the floor. Cause: • Applying finish over a coat that isn’t dry enough to be recoated yet. • Applying waterborne finish during very high relative humidity or over a floor that is too cold to be coated. • Applying an oil/solvent-based finish during very high relative humidity, causing condensation on the surface of the drying coating. This will leave a dull appearing finish once the finish is dry, often referred to as “blushing.”

Cure: Abrade/screen and recoat, being sure to increase the dry time between coats. Check with a damp rag before abrading/reapplying finish to make sure the cloudiness has disappeared. If the finish

be informed that all wood species, particularly CRAWLING cherry, Brazilian cherry and many exotics, will What it is: change color greatly as they age and are exposed Defect in which the to light. finish recedes from To minimize changes, reduce the floor’s expo- small areas of the sure to light. surface, leaving them apparently uncoated. (Photo also shows EARLY FINISH WEAR fish eyes.) What it is: Cause: The appearance of • Contamination of too much (premature) the floor or finish. wear on a relatively Often the contamination presents itself in a pat- new finish. tern left by the cause of the contamination (often a footprint or hand print). Cause: • Improper mainte- Cure: nance procedures Sand the problem areas by hand-sanding or that may include using a small electric random orbital sander, failure to fully remove and then abrade and recoat. If the problem is grit from the floor’s widespread, the floor may need to be completely surface, using water resanded. to clean the floor, or If it is determined that the problem is caused using strong cleaners by contaminants between the boards, trowel- on the floor. filling the floor may help prevent problems. When • Pet nails and chair you suspect that there is a chance of contamina- legs may contribute tion on the floor, make sure you first clean the to the problem. floor thoroughly before attempting to abrade and • Inadequate film refinish the floor. build. • Wear caused during the construction process. DISCOLORATION • Applying finish over coats that have not had What it is: enough time to gas-off and dry, resulting in im- The floor changes proper (delayed or incomplete) curing. color (darkens or • Improper sanding procedures—when the floor is lightens) over time. left too rough, finish accumulates in the bottoms Some areas may of the grooves in the floor, leaving little cover- change color more age on the “peaks,” where the finish then wears than others. through. This may give the appearance of ridges in the flooring. Cause: • Oil-modified finish- Cure: es amber in appear- Institute proper maintenance procedures, includ- ance and will yellow ing regular vacuuming and dust-mopping using even further over time—this is to be expected. an approved wood floor cleaner. Use throw rugs • Wood lying in direct sunlight will change color at each entryway and use good floor protectors over time; this is a natural change. under the legs of furniture. (For complete main- • Wood also changes color through oxidation tenance directions, see publication Technical and/or photochemical exposure, which is a Manual C100: Maintenance and Recoating.) If the change that cannot be prevented. This is a natu- cause is improper sanding, then resand with the rally occurring phenomenon. proper grit sequence and recoat. If the finish is not worn through, just abrading/recoating may Cure: be an option. Despite the pervasive myth that an oil-modified finish recoated with waterborne finish will stop ambering, ambering of oil-modified finishes cannot be prevented. If marks are left on the floor by area rugs or furniture, moving them around can equalize the change in color. Customers should

FISH EYES PEELING What it is: What it is: Defect that manifests The finish releases itself by the crawl- from the wood floor ing of wet finish or previous finish into a recognized coat. pattern resembling small “dimples” or Cause: “fish eyes.” They can • Stain or previous measure up to about finish coat that was 1 inch in diameter. not dry. You may find a tiny • Skipping abrasion particle in the middle or using too fine of a of some fish eyes, which may be the cause for grit abrasive between finish coats. some to form. • Stain not sufficiently wiped up. • Improper tacking between coats. Cause: • Surface contamination such as wax or oil-soap • Contamination in the surface. cleaners. • If the finish container has sat undisturbed for • Finishes that are not compatible. some time and has not been properly agitated, a disproportionate amount of flow and leveling Cure: agents may be put on the floor, causing a fish- Resand and recoat. Be sure to abrade well using eyed appearance. the recommended grit size between coats until completely dull. Cure: Abrade/screen and recoat. Assure that the finish used is well stirred/mixed up as directed by the PIN HOLES finish manufacturer. What it is: A defect similar to fish eyes, but very, ORANGE PEEL very small. What it is: The surface of the Cause: finish has a texture • A coat of finish that resembles an being applied over orange peel. a coat that was not dry, or a finish coat Cause: applied too thick. Sol- • A finish that dries vents are still evapo- too quickly. rating and pushing through the finish that has • A finish or sub- already started to form a skin, leaving pinhole- strate that is too cold, sized openings in the finish. This may also show causing poor flow in areas where finish has puddled. and leveling. • Use of an improper applicator that causes small Cure: bubbles to form in the finish. The bubbles then Give the floor sufficient time to totally dry, then pop, leaving small dimples in the finish. abrade/screen and recoat using correct dry times • Covering a floor before the finish has fully between coats. Follow the finish manufacturer’s cured. recommendations, including spread rates.

Cure: Abrade/screen and recoat. Select the recommended applicator for the product being applied. Make sure that the floor and the product applied have adjusted to proper temperature; consult with the finish manufacturer. A wood floor may take a few days to warm up in very cold climates, so allow for this.

POLY BEADS Cure: What it is: If a roughness problem is evident, abrad- Beads or “BBs” of ing/screening and finish that form along recoating may fix the the edges of the floor- problem. However, ing pieces. They can resanding may be be soft and sticky necessary. when first formed, but will become quite hard if left undisturbed.

Cause: • Generally, poly beads are associated with oil- SIDEBONDING based polyurethane finish, particularly higher What it is: solids/viscosity products, with a slow drying With sidebonding, the condition and excessive amount of sealer and/or edges of the individu- finish that seeps into small gaps between boards. al boards are “glued” When the product dries/skins over, the solvent together by the fin- may be trapped in the still-wet finish between the ish. It can occur with boards and tries to evaporate, forming beads on all types of finish, the surface where the wet finish oozes out. although it happens more frequently with Cure: water-based prod- Check with the finish manufacturer for its recom- ucts. (Panelization mendation. Time will allow the floor to expand and sidebonding may and contract, eventually allowing all of the un- appear similar but are different problems. For dried finish to surface. When soft, the beads can panelization, see page 11.) smear, leaving an unsightly appearance; consult with the manufacturer regarding how to remove Cause: the beads when soft. For hardened beads, the so- • Sidebonding results from the finish seeping lution is to first gently remove them with a sharp- down into the spaces between boards and gluing edged tool (i.e., scraper, plastic putty knife or the boards together. It is usually noticeable only the edge of an old credit card) and, if necessary, after a drastic decrease in humidity. abrade/screen and recoat. Do not attempt to just abrade/screen the hardened beads, as that may Cure: easily cause circular scratches within the finish. Restoring normal humidity levels may return the floor to an acceptable appearance. If there are still gaps, see the “Cure” for “Gaps, Abnormal” on ROUGHNESS/GRAIN RAISE page 9. What it is: Staining or sealing floors with a specifically designed sealer may reduce sidebonding. Consult The surface of the your finish manufacturer for other preventive wood floor is rough to steps. the touch.

Cause: • Inadequate sanding, including skipping too many grits. • Contamination of the finish during dry time. • Not allowing sufficient dry time for waterborne sealers to flatten. • Moisture causing the wood grain to rise. • Not using enough coats of finish. • Not abrading well enough between coats. • Insufficient cleaning between coats.

STAINS TANNIC ACID DISCOLORATION/ What it is: PULL/BLEEDING Discoloration on one What it is: area of the floor. Tannic acid discol- Cause: oration/pull (also sometimes called • Spilled liquids. tannic acid bleeding) • Pet stains (shown is a dark/greenish/ at left). brown discoloration • Residue from im- that may occur with proper cleaners. a freshly applied coat • Continual moisture of waterborne floor leading to mildew finish on a wood spe- (black), decay (brown/white) or alkaline condi- cies containing high tions (white). levels of tannic acid (in the wood flooring busi- Cure: ness, typically oak). This discoloration develops in the surface of the wood and may partially bleed Cloudy surface finish can be fixed by lightly rub- up in the applied finish. Tannic acid discolors bing with a proper cleaner and buffing, although when it gets in contact with materials that are al- some stains require abrading/screening and re- kaline by nature, such as ammonia. Tannic acid coating. Pet stains frequently require total board is water-soluble and may discolor when it gets replacement. For moisture problems, eliminate in contact with iron (carpet staples) and water, the source of moisture, then evaluate the condi- which usually appears as a bluish/dark grey dis- tion of the flooring before deciding on corrective coloration in the wood. Waterborne finishes are action. typically manufactured with pH adjuster (such as ammonia) and therefore are known to potentially contribute to tannic acid discoloration on woods STICKY BOARD SYNDROME containing higher levels of tannic acid. What it is: The finish will not adhere or cure properly on one Cause: or more boards. • Excessively thick applied finish in localized areas (puddles, heavy streaks, etc.). Cause: • Not using a sealer well-suited for blocking or • Excessive tannic acid or pH imbalance in the reducing tannic acid discoloration. wood. This is most common with oil-modified • Sealer applied thin in localized areas or areas finishes and white oak. missed by the sealer (“holidays”). • Too much stain, and then finish, applied over • Applying a finish over a sealer that has not suf- very open grain. ficiently dried.

Cure: Cure: When one board or several boards scattered • The coating and the discoloration needs to be throughout the floor will not take stain or finish, removed down to bare wood in the affected area the most common solution is to repair the floor before recoating. Small areas can be taken care of by replacing the boards. using a sharp scraper and sandpaper, but when the discoloration is widespread across the floor, it is often best to resand the floor. • First apply a specially designed sealer (as recommended by the manufacturer of the finish) for reducing/preventing tannic acid discoloration. Apply this consistently, without leaving heavy spots or thin spots. • When the sealer is abraded, abrade it lightly, moving along swiftly without abrading through the sealer coat. • Apply waterborne finish coats evenly without leaving puddles of finish in one area for too long, as puddles may cause an adverse reaction with tannic acid in the wood. • A thinner first coat of finish will reduce the like- lihood of adverse reactions with tannic acid in the

wood. Subsequent coats may be applied as thick Cure: as recommended by the manufacturer. • Small affected areas should be scraped down carefully to a dry surface, allowed to dry/cure further and the transition sanded smooth before UNEVEN SHEEN LEVELS touching up and recoating. • When large areas are affected, it is best to (see also “Applicator Streaks”) resand the floor before recoating (be careful with What it is: sanding dust from fresh coats of oil-modified The sheen of the fin- polyurethane, which is extremely combustible). ish is inconsistent. • When applying finish, use the recommended spread rate for the product being applied and be Cause: sure that the ambient temperatures of both the • Insufficient mixing floor and air are at the recommended tempera- of finish prior to ap- ture. (Note that hardwood floors do not heat up plication. instantly when the heat gets turned on; it is best • Uneven sanding. to turn up the heat a few days before starting a • Uneven finish thick- job. Cold crawl spaces can be a serious problem.) ness. • If needed, allow more dry/cure time between • Illusion caused by coats. lighting. • A contaminated finish applicator, such as a lanolin-rich lambswool applicator that hasn’t been thoroughly cleaned.

Cure: Abrade/screen and recoat. If lighting is the cause, discuss with the customer the reasonable inspection position for looking at a hardwood floor—from a standing position under normal lighting conditions.

WRINKLING What it is: Once the finish starts to dry, it takes on the appearance of the skin of a dried prune. Wrinkling may happen with all types of floor finish, but is more likely to occur with oil-modified polyurethane.

Cause: • A coat of finish applied over a previous coat that has not dried/cured sufficiently for recoating. • Solvent in the applied coat softening the layer beneath, such that when the newly applied finish coat starts to dry, it begins to move along with the coat below, causing wrinkling. • A finish coat applied in excess, creating puddles. • A floor too cold for application, such as over a cold crawl space. • An incompatible finish applied over another finish, such as conversion varnish over waterborne or oil-modified polyurethane finish.

Applicator Streaks ...... 14 Insects ...... 10

Bleed Back ...... 14 Loose Floors (see “Squeaky/Loose Floors/ Popping) ...... 13 Bubbles ...... 14 Orange Peel ...... 17 Buckling ...... 6 Overwood/Underwood ...... 11 Chatter/Wave Marks ...... 6 Panelization ...... 11 Checks ...... 6 Peeling ...... 17 Chipping ...... 15 Picture Framing (“Halo”) ...... 11 Cloudy Finish ...... 15 Pin Holes ...... 17 Compression Set ...... 7 Poly Beads ...... 18 Cratering ...... 15 Popping (see “Squeaky/Loose Floors/ Crawling ...... 16 Popping) ...... 13

Crowning ...... 7 Roughness/Grain Raise ...... 18

Cupping ...... 7 Sanding Marks ...... 12

Delamination ...... 8 Shake ...... 12 Dents ...... 8 Shellout/Dishout of Springwood ...... 12 Discoloration...... 16 Sidebonding ...... 18 Dish Out ...... 8 Slivers/Splinters ...... 13 Dishout of Springwood (see “Shellout/ Splinters (see “Slivers/Splinters”) ...... 13 Dishout of Springwood” ...... 12

Early Finish Wear ...... 16 Squeaky/Loose Floors (“Popping”) ...... 13

Endlifting ...... 9 Stains ...... 19

Face-Checking ...... 9 Sticker/Stick Stain ...... 13

Fish Eyes ...... 17 Sticky Board Syndrome ...... 19

Flooded Floors ...... 9 Tannic Acid Discoloration/Pull/Bleeding ....19

Gaps, Abnormal ...... 9 Uneven Sheen Levels ...... 20

Gaps, Normal ...... 10 Unevenness of Entire Floor ...... 13

Grade Problems ...... 10 Wave (see “Chatter/Wave Marks”) ...... 6

Greenhouse Effect ...... 10 Wrinkling ...... 20

NWFA Technical Manual Committee • Page 16: Crawling photo courtesy of Johannes Members 2010-2011 Boonstra, Synteko Floor Finishes. Discoloration • Janet Sullivan, Lenmar Inc., Chair photo courtesy of Rick Jones, Swiff-Train • Sprigg Lynn, Universal Floors Inc., Board of Company. Top early finish wear photo Directors Liaison courtesy of Wayne Lee, Cardinal Hardwoods • Johannes Boonstra, Synteko Floor Finishes & Tile. Bottom early finish wear photo by Kim • Craig Dupra, Installers Warehouse Inc. Wahlgren, Hardwood Floors. • John Freeto, WoodCraft Wood Floors Inc. • Page 17: Fish eyes photo courtesy of Johannes • Mike Johns, Bostik Inc. Boonstra, Synteko Floor Finishes. Pin holes • Mike Kearns, Primatech Inc. photo courtesy of Craig Dupra, Installers • Neil Moss, Armstrong Floor Products N.A. Warehouse Inc. • Kevin Mullany, Benchmark Wood Floors Inc. • Page 18: Poly beads photo courtesy of Craig • Jim Schumacher, 3M DeWitt, RLC Engineering. Roughness/grain raise and sidebonding photos by Kim Wahlgren, Publication Editors Hardwood Floors. • Kim Wahlgren, Hardwood Floors • Page 19: Tannic acid discoloration/pull/ • Doug Dalsing, Hardwood Floors bleeding photo courtesy of Johannes Boonstra, Synteko Floor Finishes. Art Director • Page 20: Wrinkling photo courtesy of Johannes • Scott Maurer, Hardwood Floors Boonstra, Synteko Floor Finishes.

Photo Credits • Cover: Background photo courtesy of Harris- Tarkett. Inset photo by Dale Hall Photography. • Page 6: Buckling photo courtesy of Action Inspection Service. Checks photo by Kim Wahlgren, Hardwood Floors. • Page 7: Crowning photo courtesy of Craig DeWitt, RLC Engineering. Cupping photo courtesy of Genia Smith, Accent Hardwood Flooring. • Page 8: Dents photo by Kim Wahlgren, Hardwood Floors. Dish out photo by Steve Tregeagle Photography. • Page 9: Face-checking photo courtesy of Roy Reichow, National Wood Floor Consultants. • Page 10: Photo courtesy of Matt Skowron, The Floor Detective. • Page 12: Sanding marks photos by Kim Wahlgren, Hardwood Floors. Shellout/dishing of springwood photos by Steve Tregeagle Photography. • Page 14: Applicator streaks photo by Steve Tregeagle Photography. Bleed back and bubbles photos by Kim Wahlgren, Hardwood Floors. • Page 15: Chipping photo by Steve Tregeagle Photography. Cratering photo courtesy of Craig Dupra, Installers Warehouse Inc.

For more technical information, consult the other chapters in the NWFA’s Technical Manual Series:

National Wood Flooring Association 111 Chesterfield Industrial Blvd. • Chesterfield, MO 63005 800/422-4556 • 636/519-9663 (local and int’l) fax: 636/519-9664 [email protected] • www.nwfa.org