By Brett Miller, NWFA Vice President Technical Standards, Training & Certification
Flooring contractors know that installing real wood floors offers significant income opportunities. Real wood is an aspirational flooring product that requires specialized installation skills, which demands more money than some other flooring product installations. It also generally is installed in higher-income homes, and for larger projects, which often translates into higher-paying jobs.
Then there are the hundreds of millions of square feet of wood flooring that is already installed and will need to be refinished at some point. In fact, the 2020 U.S. FLOOReport states that wood flooring specialty contractors earn more than 30% of their total revenue from refinishing existing wood floors. If you are not offering these services to your customers, you could be leaving profits on the table.
Take care to ensure you have the right skills to fill this need, so you can have a big impact on your company, while being able to fix problems that occur with finish applications. This will increase not only your profitability, but your value to your customers as well.
There are two common issues that arise with finish inconsistencies: streaks and uneven sheen/gloss levels. Following are steps to first identify both issues, and then solutions for repairing them.
Streaks in the finish are defined as visible ridges, lines or marks left on the wood floor, representing the application tool used from any stage of the finishing process.
Finish streaks can have a variety of causes, as follows:
- Improper finish application (not feathering out or coating cross-grain).
- Improper applicator used to apply the finish.
- Using an applicator that has hardened spots in the fibers.
- Inconsistent finish film thickness or improper coverage rates, where the finish was applied too heavy or too thin.
- Matting agents in the finish not mixed adequately.
- Expired finish or expired hardeners/crosslinkers affecting the application and flow of the finish.
- Finish stored in or exposed to extreme temperatures outside of the manufacturer recommendations.
- Finish not acclimated to room temperature prior to application, where the jobsite conditions are too hot or too cold.
- Excessive air movement over the surface causing the finish to partially set up/skin over before it has a chance to flow and level.
- Applying finish over a hot surface (under a window with direct sunlight, or radiant heat) causing the finish to set up, dry too rapidly and not flow properly during the application process.
- Multiple coats of film-forming finish can sometimes exacerbate applicator marks left from otherwise properly applied finishes. This is seen most commonly with multiple coats of satin or semi-gloss sheen finishes.
- Inconsistent application of colorants (dyes, stains), reactives (bleach, iron acetate), or sealers.
- Finish applied over undried stains, colorants or like-solvent aniline dyes, unintentionally pulling or reconstituting the color into the rest of the floor.
- Finish applied over chemical reactives, pulling or reactivating the chemical.
- With factory-finished floors, inconsistent or uneven application of colorants, reactives or finishes from the manufacturing finishing processes.
- The ambient conditions of the jobsite must be at normal living conditions and within the finish manufacturer recommendations, prior to making repairs. Finish coats may require extended dry times dependent on many variables.
- Choose abrasives to adequately remove the marks from the floor, then proceed upward in grit sequence to the appropriate grit for the finish being used.
- Select an applicator better-suited for the type of finish being applied. For example, a roller application may be better-suited for flooring that is a multi-directional.
- Follow the finish manufacturer’s directions.
- With colorant/reactive application-related streaks, a resand may be necessary.
Uneven Sheen/Gloss Levels
Uneven sheen or gloss levels is defined as the sheen or gloss level of the final finish coat being inconsistent from one area of the floor to another. Note that as film-forming finish products decrease in gloss, they increase in the amount of matting agents. Lower sheen products have the most matting agents, and therefore more easily can result in uneven sheen levels. Sheen/gloss levels should not be assessed until all final coats have been applied and are cured fully.
Uneven sheen or gloss levels can have a variety of causes, as follows:
- Issues related to application can include the following:
- A contaminated finish applicator.
- Improper mixing of the finish prior to application where the matting agents are not mixed into the film-finish adequately.
- Allowing the finish to sit too long after mixing, and before applying.
- Not bundling/batching finish from multiple containers on the job.
- Finish film thickness inconsistencies from one area to another across the flooring surface, normally attributed to not being applied evenly, being applied at improper coverage rates, or leaving applicator ridges, puddles, lap-lines or pools in the top coat of the finish.
- The top-coat being applied over another coating that has not dried adequately, trapping solvents within the film.
- Flooring top-coated with lower-matte sheen film-finishes applied over higher-gloss base coats can exhibit sheen variations when the finish film thickness varies. This issue is more common with textured floors (wire brushed, scraped, heavy grain).
- Excessive air movement or high temperatures causing the finish to dry too rapidly during application.
- Ambient jobsite conditions being too cold for finish application.
- Hot spots on the wood floor during finish application affecting the drying conditions.
- Issues related to the finish itself can include the following:
- Expired finish and/or hardener or catalyst.
- Finish that has been exposed to temperatures outside of manufacturer-recommended ranges, during storage or application.
- After proper mixing, the matting agents within the finish inadequately disperse and are unable to remain suspended long enough to coat a floor.
- Improperly labeled finish.
- Sheen inconsistencies from one batch of finish to another.
- Adding non-manufacturer recommended substances to the finish, or adding too much of manufacturer-recommended thinners, dry-time extenders, bond-enhancers or other substances to the finish.
- Issues related to maintenance can include the following:
- Using cleaning products not recommended by the finish manufacturer.
- Residue left behind from maintenance products.
- Heavy foot traffic.
- Excessive or aggressive maintenance practices.
- Using steam cleaners.
- Issues related to factory-finished flooring can include the following:
- Factory-finished flooring being mislabeled.
- Factory-finished flooring sheen inconsistencies from one package to another.
- Factory finish applied improperly, inconsistently or at different thicknesses.
- Uneven sanding of the floor. Inconsistent scratch patterns and abrasive paths can adversely affect how the finish appears on the surface.
- Natural characteristics or porosity differences within the wood.
- Naturally occurring oils from various exotic wood species adversely affecting the drying process.
- The normal and expected appearance of natural oils or other non-film-forming finish systems.
- Unfilled cracks or voids taking the finish coats inconsistently and unevenly.
- Optical illusion caused by lighting conditions, height differences, elevation changes, floors that are sculpted, distressed, or otherwise possessing underwood/overwood, or by a floor that is not flat.
- Conditions within the jobsite affecting drying conditions should be taken into account prior to addressing the issue, or may not be addressable with repairs, and should be considered when evaluating the conditions.
- Correct improper maintenance practices. A deep clean and recoat may be necessary in some cases. Check with the finish manufacturer for processes and products to use in each scenario.
- Abrade and recoat to correct sheen inconsistencies when applicable.
- For naturally occurring characteristics in any wood species, the end-user should be made aware of the variability within each wood species and how they may affect the outcome of the finish being used.
- Check with the flooring manufacturer for discrepancies in sheen levels within the same floor for repair recommendations.
- Replace boards or sections as necessary and with manufacturer support when factory-finished flooring is mislabeled.
- If lighting or subflooring is the issue, address appropriate evaluation standards (normal lighting, standing position on the floor being assessed).
- In some cases, no corrections may be necessary.
The National Wood Flooring Association has detailed information about wood flooring finish inconsistencies available through NWFA University, an online training platform that is convenient and affordable. More information is available at https://nwfa.org/nwfa-university.aspx.