By Brett Miller, NWFA Vice President Technical Standards, Training & Certification
Flooring contractors know that a perfect wood flooring installation and sanding job can be ruined with a bad finish application. Knowing how to identify and correct unacceptable finish issues can be a valuable service for your customers.
Poly beads are small round balls, beads or “BBs” that form along the joints of individual boards. They can be soft and sticky when first formed, and will harden when undisturbed.
- During application, finish can collect in voids/gaps, where it cures at a much slower Later, when the moisture content of the flooring increases, the uncured finish can squeeze out. This is most common with oil-based urethane finishes, higher solids/more viscous finishes and conversion varnishes.
- Slow drying conditions, where RH is high or the floor is too cold, can give finish the opportunity to seep into voids/gaps.
- The flow of water-based finishes over and into voids/gaps can result in slight finish pooling and appear as small bumps along board seams once the coating has dried.
- With on-site water-based UV coatings, during the curing process the heat can force excess product in gaps to bead up.
- Control seasonal RH fluctuations within the facility.
- Remove hardened beads with a scraper, putty knife or razor blade.
- Recoat the floor as necessary after successful removal of the hardened poly beads.
Bubbles are raised, air-filled bumps visible in the film of the finish, both popped and unpopped.
- Improper applicator used to apply finish.
- Improper tacking solvents used before or between coats.
- Overworking finish or sealer during application.
- Not mixing the finish or sealer properly.
- Finish or sealer that has been mixed and not allowed appropriate “rest” time before use.
- Finish or sealer applied too thick, which traps solvents.
- Air movement across the finished floor causing the finish or sealer to dry too rapidly and skin-over immediately after application, trapping air bubbles.
- Jobsite conditions that are too hot or too cold, causing the surface of the finish to dry too quickly, trapping bubbles at or below the surface.
- Applying finish or sealer over a hot surface (under a window with direct sunlight or over radiant heat) causing the finish or sealer to set up too quickly and not allowing it to flow properly.
- Prior coats not being abraded or sufficiently cleaned between coats of finish or sealer, as per manufacturer recommendations.
- Site-applied UV finishes cured prior to returning to the manufacturer-recommended moisture content levels.
- UV lamps left in one place for too long, resulting in burnt and blistered finish.
- Finish or sealer that had been exposed to temperatures outside of manufacturer-recommended ranges, prior to or during Extreme cold/freezing conditions often reduce the effectiveness of the defoamers in the finish.
- Expired finish, sealer or catalyst/hardener, which reduces the effectiveness of defoamers in the finish.
- Adding non-manufacturer-recommended substances to the finish, or manufacturer-recommended substances in improper amounts.
- Manufacturing defects, including being too thick, having ineffective defoamer(s) or inadequate reactive hardener.
- With factory-finished floors, the undried finishes, pigments, stains or colorants that are absorbed into open grain, knots, checks, burls or other open voids during the application process may sometimes not dry at the same rate as it does on the A gain in moisture can cause wood cell cavities to swell, squeezing out the undried residual to the surface of the boards.
- Address any jobsite conditions that may adversely affect the drying of the finish or Ambient conditions of the space must be at living conditions, and within the finish manufacturer recommendations prior to any repairs.
- Abrade and recoat the floor using the appropriate application tool and spread rates.
- Choose a scraper or abrasive to adequately remove the bubbles from the floor and proceed upward in grit sequence to appropriate grit for finish or sealer being used.
- Select a fresh batch of finish that has been stored under favorable conditions.
- Where bubbles are deep below the surface coating, it may be more effective to resand the affected area.
- Follow the finish manufacturer recommendations.
Crawling occurs when the finish film is repelled from areas of the surface, leaving the appearance of thin or uncoated areas, often in long, oval shapes.
- Insufficient removal of already-existing blemishes prior to subsequent coats.
- Contamination of the floor where foreign substances such as maintenance products, wax, grease, oils, polishes, soaps, overspray from other sources, or other contaminants are present before coating or have been introduced between coats.
- Foreign substances or other contaminants remaining between boards or within voids affecting the new finish application.
- Using finish that has been exposed to temperatures outside of manufacturer-recommended ranges, during storage or application.
- Expired finish or catalyst/hardener.
- Improper mixing of the finish.
- Hot-coating (recoating without abrading and/or before previous coat had adequate dry time) outside of manufacturer recommendations.
- Recoating a cured floor outside of the manufacturer-recommended preparation.
- Instability of defoamer or surfactant systems within the finish.
- Adding non-manufacturer-recommended substances to the finish or adding too much of manufacturer-recommended thinners, dry-time extenders, bond-enhancers or other products to the finish.
- Application related:
- Incompatible finish or sealer in the applicator from previous coatings not adequately cleaned out prior to application.
- Excess water in the applicator that may imbalance the finish defoamer system.
- Applicator cleaned with incompatible solvent for the finish being used.
- Coating over a not-yet-cured finish or sealer.
- Coating over an incompatible finish or sealer:
- Perfluorooctane sulfonate (such as Teflon/Scotchgard) infused finishes that cannot be recoated.
- Wax finished with urethanes or oils.
- Incompatible finishes from different manufacturers.
- Natural oils finished with incompatible urethanes.
- Abrade and recoat the floor using the appropriate application tool and spread rates.
- Sand or scrape the affected areas, then recoat as necessary.
- When the floor or finish has been contaminated, or when the problem is widespread, a resand and finish may be necessary.
- If the crawling is caused by contamination between the boards, trowel filling the floor may help prevent further issues.
Orange peel occurs when the surface of the dry finish film looks and feels like the texture of an orange peel.
- Using a roller to apply finish that is not suitable to be rolled, improper use of the roller or use of improper-size nap roller sleeve.
- Overworking finish or sealer during application, creating air bubbles/foaming to develop within the applicator, causing the finish to not flow out completely before the finish begins to set-up.
- Improper coverage rates where finish is applied too thin or too thick.
- Using a finish that has not been brought to room temperature and is too cold, causing poor flow and leveling.
- Solvent additives or dry-time-extending retarders not used when suggested by the finish manufacturer for unfavorable/drier coating conditions.
- With factory-finished flooring, orange peel may happen when the finish was applied by rollers, and the roller texture remains.
- Environmental conditions:
- Hot, dry conditions causing finish to dry/flash-off too quickly.
- Cool, damp conditions forcing the finish to dry at a slower rate than intended.
- A substrate that is too hot or too cold during finish application, causing poor flow and leveling.
- Airflow causing the surface of the finish to skin over, and not flow or level as necessary.
- Abrade and recoat using the appropriate application tool and spread rates, after the finish and jobsite conditions coincide and have been brought to a favorable range within the finish manufacturer recommendations. Ambient conditions of the space must be at living conditions and within the finish manufacturer recommendations prior to any repairs.
- In some situations, finish manufacturers may recommend adding solvent additives or dry-time-extenders to improve the finish flow and leveling properties.
- In some cases, a resand may be necessary.
- For factory-finished floors, replacement of affected boards may be necessary.
The National Wood Flooring Association has detailed information about wood flooring finish repairs available through NWFA University, an online training platform that is convenient and affordable. More information is available at nwfa.org/nwfa-university.aspx.