Wood floor finish problems can occur during the finishing of wood floors or at a later date. With both factory-applied finishes and site-applied finishes, the problem may be with the finish or a different cause.
Preventing and Correcting Wood Floor Finish Problems
Adhesion
With an adhesion concern, the coating is easily removed from the wood. Common causes include improper surface preparation, finishing over oil, grease, or other contaminants, improper curing schedule, poor substrate integrity, and incompatibility of one coat with another or with the substrate.
The solutions for adhesion include ensuring a proper pretreatment; the surface to be finished must be thoroughly clean and dry, adherence to a proper curing schedule, and ensuring that the substrate has good integrity, including proper sanding.
The correction for an adhesion problem is the replacement of damaged boards or sanding and refinishing as may be necessary. If the problem is caused by substrate integrity, the problem may not be solved.
Alligatoring
Alligatoring is a condition in which the finish pulls away from itself, causing ridges in the finish, similar to an alligator’s skin. This condition can occur in both water-based and oil-modified finishes. There are many possible causes, including poor wetting of the finish, contamination of the finish, application under cold temperatures, application of a new coat before the previous coat has dried, application of a heavier coat than is recommended, or the use of thinners that cause the finish to dry too quickly.
The solution is to screen and recoat after the finish has dried sufficiently.
Application Streaks
Application streaks are usually associated with water-based finishes. It often occurs when an improper spread rate is used – too much or too little finish is applied – or if the finish is not applied evenly. Excessive air movement and abnormally high temperatures can also be responsible for causing the finish to dry too quickly, so that a wet edge of finish is pulled over one that has already dried. The problem can also be caused by applying a satin or semi-gloss finish that has not been stirred properly.
The solution is to screen and recoat after the finish has dried sufficiently.
Blistering
Blistering has the appearance of small, swollen areas, like a water blister on the human skin. Pinpoint holes in the finish. Lack of gloss if blisters are minute. Broken edge craters if the blisters have burst. Blistering is caused by improper thinning solvent – too fast evaporating. Excessive film build-up traps solvents. Additional causes on prefinished floors include excessive temperature in the first oven zone. Insufficient flash off time before baking. Gases entrapped in the substrate during the manufacturing process are forced out through the coating when baked at high temperatures. Solutions include reducing with slower evaporating solvents. Reduce film build. Reduce the temperature in the first oven zone. Increase flash off time before baking. Reduce overall oven temperature.
The correction for blistering is to sand and refinish or replace blistered boards.
Crater (Fisheyes, Pitting)
Cratering and fisheyes have the same appearance but not caused by the same thing.
Cratering gives the appearance of small crater-like depressions in the film. Cratering is usually due to foaming of the finish coupled with fast setting conditions where the bubble but do not have enough time to flow smooth. Cratering is also caused by improper cleaning of the wood prior to finish application. Oil, water or other contaminants. Low film build. Overly wet application.
Fisheyes are caused by surface tension problems in the finish. The defoamers and/or wetting agents are affecting the surface and causing a difference from normal wetting of the finish.
Solutions for prevention include assuring that the surface to be finished is thoroughly clean and dry. Increase film build. Use proper maintenance to prevent contaminants. Eliminate contaminants from entering application areas. Corrections include replacement of cratered boards or sand and refinish as may be necessary.
Bleed Back
Bleed back is a condition associated with stain application. This condition occurs when excess stain seeps from the grain or from the spaces between boards. The most obvious cause is excessive stain application, but low-viscosity stain may also be the culprit. During application the solution is to wipe off the excess stain and let it dry thoroughly before applying another coat.
If finish has already been applied over bleed-back, a complete resand is often required.
Crawling
Crawling refers to the process of walking away from a given area on the substrate. When it is on an edge, it is referred to as non-wetting. When in the middle of the board, it is crawling. Crawling is not wetting the surface below. It can be caused by contamination, but also by incompatible finishes.
Brittleness
The brittle coating of the wood floor finish displays excessive rigidity and flakes off when scraped.
The more common causes of a prefinished floor include overbaking and excessive temperature, and/or excessive time in the oven.
Other common causes include excessive film build. Incompatibility of one coat with another or improper surface preparation.
Solutions for brittleness include avoiding overbaking. Reduce film build. Follow recommended practices using compatible materials and ensuring proper pretreatment.
Correction is to replace boards of concern or to sand and refinish.
Dirt
Dirt and foreign particles dried in the finish. The common causes for this include improper cleaning of the substrate, a dirty work area, or equipment.
Solutions for prevention include assuring that the surface to be finished is thoroughly clean. Be sure all equipment is clean. Keep all finished containers closed to prevent contamination. In the plant, ovens must also be kept clean.
Corrections include screening and coating or sanding and refinishing as may be necessary.
Discoloration
Some wood floor finishes are amber in appearance and will yellow even further over time. Wood lying in direct sunlight will fade over time.
These are natural changes – the former condition cannot be prevented, despite the pervasive myth that an oil-modified finish recoated with a water-based finish will stop ambering. The latter condition can be prevented by shading the light source.
Erratic discoloration can also occur, especially in white oak, if a good sealer is not used. This is called tannin pull.
Excessive and Early Wear
Excessive and early wear is often caused by improper maintenance procedures that have either failed to fully remove grit from the floor’s surface or the introduction of water or strong cleaners. Dog nails, high heels, and chair legs also contribute to the problem. Make sure the customer understands proper maintenance procedures, including regular dust-mopping with an approved wood-floor cleaner. (Some cleaners may leave a residue that will prevent good adhesion on a recoat.) If recoating is necessary, the owner should pay for it.
Lifting (Peeling)
With lifting, there will be raising and sealing of the wet film or peeling when the surface is dry.
Common causes of peeling include the improper curing of the previous coating. Solvents in the topcoat are too strong. Application over improperly cleaned surfaces.
Solutions for peeling include proper surface preparation. Be sure the surface to be coated is properly cured. Use only recommended thinners.
Correction includes the removal and replacement of damaged board or sanding and refinishing as necessary.
Orange Peel
If the surface of the finish has a texture that resembles an orange peel, the problem may have been caused by rolling a finish, which then dries too quickly. When that happens, the texture is “frozen” into place before the finish has a chance to flow out and level. The solution is to screen and re-coat.
Peeling, Bubbles, Blisters, and Fish-Eyes
Any of these conditions can mean that the floor was not sufficiently screened between coats of finish, or that soap or some other contaminant substance was not removed before coating.
It’s also possible that the affected coat is incompatible with the finish or stain previously applied, or a contaminated applicator may be responsible.
Problems in the top-most finish coat can be screened and re-coated, although severe problems may require complete sanding and refinishing.
Pin Holes
Pin holes have the appearance of small, swelled areas like a water blister on human skin. Broken edge craters if the blisters have burst. Lack of gloss if blisters are minute.
Pin holes are caused by gases entrapped in the substrate during the manufacturing process that are forced out through the coating when baked at high temperatures.
Other common causes of pin holes include moisture in the finish during application, Improper thinning of solvent resulting in excessively fast evaporation, and excessive film build-up from trapped solvents.
An additional cause on factory finished floor includes excessive temperature in the first oven zone and insufficient flash off time before baking.
Solutions during site and factory application include using slower evaporating solvents and reducing film build. For factory applications, additional solutions include the reduction of temperature in the first oven zone. Increase flash off time prior to baking. Reduce overall oven temperature. The site-related correction is to sand and refinish.
Solvent Popping
Solvent popping on the finish of a wood floor appears as small, swollen areas like a water blister on the human skin, pinpoint holes in the finish, a lack of gloss when the blisters are minute, or broken edge craters if the blisters have burst.
Gases entrapped in the substrate during the manufacturing process are forced out through the coating when baked at high temperatures.
Solvent popping is caused by improper thinning solvent, resulting in excessively rapid evaporation, excessive film build, trapped solvents, excessive temperature in the first oven zone, and insufficient flash off time before baking.
Solutions for solvent popping include reducing with slower evaporating solvents, reducing’s film build, reducing of temperature in the first oven zone, increasing the flash off time prior to baking, and the reduction of the overall oven temperature. The correction for solvent popping is to sand and refinish.
Stains
Spilled water and other liquids, including the residue from incompatible cleaners, can stain the finish.
Cloudy surface finish can be fixed by lightly rubbing with a proper cleaner and buffing, although some stains require screening and recoating. Strong chemicals should not be used to remove stains.
Sticky Board Syndrome
Sticky board syndrome occurs when excessive tannic acid in the wood prevents the finish from adhering to the wood. This is most common with oil-modified finishes and with white oak. When one board or several boards scattered throughout the floor will not take stain or finish, the only solution is to repair the floor by replacing the boards.
Uneven Gloss or Sheen Levels
Insufficient stirring of the finish before application, a contaminated finish applicator, and uneven sanding or finish thickness are typical culprits. All require rescreening and re-coating. Great care should be taken when using different sheen levels. Sometimes, multiple coats of satin, three or more coats, will start to give a hazing look to the finish coat.
FAQs Wood Floor Finish Problems
How can I prevent and fix discoloration or uneven sheen in my hardwood floors?
Discoloration can be natural over time or from exposure to sunlight; shading windows helps prevent fading. Uneven sheen is usually due to improper stirring or sanding and can be corrected by rescreening and re-coating the floor.
What causes blistering in wood floor finishes, and how can it be corrected?
Blistering is caused by excessive evaporation of solvents, too much build-up, or high temperatures during application or baking. To fix this, sand the affected areas and refinish or replace the blistered boards.
Why do application streaks happen in wood floor finishes and how can I fix them?
Application streaks often occur with water-based finishes when not applied evenly or with the wrong spread rate. Allow the finish to dry fully, then screen and recoat to smooth out the streaks.
How do I fix alligatoring in my finished wood floors?
Alligatoring, which looks like the floor finish pulls apart creating ridges, can be fixed by screening the finish and applying a new coat once the existing finish has dried completely.
What causes wood floor finish to peel or lift off?
Peeling or lifting occurs when the finish is not properly cured, the surface was not correctly cleaned before application, or incompatible products were used. Proper surface preparation and using recommended materials are key to prevention.
Who should I call if I have a finish issue with my new hardwood floor?
Contact your dealer first and let them know about your concern so that they may address it for you. If you have a factory finished floor, follow the steps it gives for resolution. If you need an independent inspector, TW Group serves the states of Oregon and Washington and is available for travel.
