The NWFA Expo offers a wealth of educational opportunities for professionals looking to grow and expand their industry knowledge and technical expertise. “The Science Behind Finish Failures” is one of the education topics that will be covered during the Pre-Expo Symposium on Tuesday, April 15. A panel of finish experts will discuss common finish failure causes, and the scientific principles behind them.
The objective is to help flooring professionals better prevent failures at the jobsite, and to give inspectors a clear direction to begin investigating causes for failure. Finishing a floor correctly is not only an art, but a science.
Ethan Erickson, chemist for Arboritec, will be part of this panel discussion. Below, he previews the session by answering some common questions related to finish failures.
How has science contributed to increased durability and performance? There have been fabulously performing, very durable finish systems for decades. However, environmental concerns and other factors have pushed scientific innovation and the abandonment, or dramatic changes to, these formulations. There has been an increasing focus on, and innovations in, waterbased coatings, then into lower-volatile organic compound (VOC) versions of the same, then ones with more water-dispersible content (“PUDs,” including, where relevant, aliphatic diisocyanate cross-linkers/and with more water-dispersible content, other cross-linking options and developments), polymers prepared by methods other than isocyanates, cool combination polyurethane-acrylic hybrid dispersions (PUAs), innovations in matting technology and additives used in said coatings, faster cure times and properties advance the development of viable site-cured UV coatings (and increased hardness relative to conventional 2K and 1K coatings) and the equipment to cure them (including in the oil realm), the development of a range of wood “reactives,” expansion of sealers to accommodate a range of looks and uses, and others.
Scientific advancements have pushed oil-based coatings to continually trend lower in VOC, as well; polymers have been prepared to be faster-drying by modifications to the nature of and/or to increase the unsaturated content (“fatty acid” functionality/ability to cross-link), by modifications in dedicated “driers” themselves, and others. There has been huge growth in the natural/penetrating oil finish market, with low to no VOC offerings, fabulous coloring options, some with cross-linkers or UV-cured for enhanced properties, and others.
We cannot leave out the leaps in factory-finished flooring from the early days. From the clarity and durability of the finish systems (including the addition of oil options), to the flooring itself, which can be very high-tech.
These innovations have increased performance in a number of ways, including addressing a wider range of consumer demands, being friendlier to the environment, generally easier to use, and put into full use quicker. Have these innovations increased durability? From a strictly wear or hardness perspective of a specific coating or finish system, in some ways and situations, yes. However, if a specifier/contractor/consumer does not pick a finish system that is suitable for the use it will get or start with and follow manufacturer and/or NWFA guidelines for use and maintenance, it almost certainly will not be as durable as expected.
In what ways can improperly mixed finish impact results? Perhaps the easiest aspect of improper or inadequate mixing can be seen with any finish (water or oil-based) that has advertised sheen other than gloss – if there is no mixing of these, as in, open the lid and pour it out, the resulting dried sheen will usually be higher, maybe considerably higher with an ultra-matte or matte finish. Another component is insufficient mixing of a hardener or crosslinker, which can lead to incomplete development of or variableness of film properties like adhesion, chemical resistance, and hardness, which can translate to said variableness in a succeeding coat. These are not mixed or added in the factory; we rely on the contractor to do so on-site, while following manufacturer recommendations. We do NOT want you to have problems (it costs both of us time and money), so the recommendations on the back of the jugs and hardener/crosslinker bottles are based on our lab and field testing. Further, it is possible for components to separate over time, exacerbated by storage situations of abnormal heating/cooling cycles. This is one reason that manufacturers print a “best used by,” expiration date, etc. on each unit of coating product. In this case, effects could be uneven or higher/lower sheen, issues with flow and leveling, drying and curing, properties development, etc.
How critical is it to abide by cure/dry times? Manufacturers provide recommended dry and cure times to allow the finish to achieve maximum performance, including adhesion, flexibility, chemical resistance, hardness, etc. Said dry/cure times are based on lab, then field testing. Believe me, we do NOT want you to have problems, so we do our due diligence ahead-of-time. Remember, these times work in concert with our recommended temperature and RH ranges for storage, floor preparation, coating, use, and maintenance.
What causes chipping/flaking finish? There are numerous possible causes of chipping/flaking finish, including:
- Poor intercoat adhesion.
- Inadequate intercoat abrasion or surface preparation.
- Coating too early over a previous coat/lack of adhesion to stain at board edges, either remaining isolated along a seam or, once removed, migrating inward (more so in an overwood situation [see above.])
- Chemical damage. Think old-school nail polish remover (acetone) and others that can first swell or otherwise deform some finishes, after which said finish may flake/chip off; usually confined to the damaged area.
- Too large of a difference in the elasticity of adjacent coatings.
- Overwood. Overwood places a finish system in a geometric position that it is not designed for: concentrated force perpendicular to the coating system. Even the best coating system, with great adhesion, can fail in this situation.
- Combination(s) of the causes listed, exacerbated by excessive floor movement, exposure of the floor to too high/low of temperatures/RH.
What can be done if finish is peeling on a floor? The easiest solution is to place a rug (with the proper backing) over it; strange at first, but you get used to it. Seriously, folks, first identify the cause, then proceed accordingly.
For a true spot failure, like pulled tape or a chemical drip, resolution may be as simple as isolating a board or boards and applying another coat (after proper preparation). Or it may require resanding said boards and building them all the way back up. Obviously, matching the sheen of the surrounding floor can be a challenge, especially with matte finishes in low-angled light conditions.
If the cause is something that affects the entire floor, such as inadequate intercoat abrasion, then it is likely that more peeling will occur and unlikely that a buff-and-recoat will not “solve” the problem.
How could using the wrong maintenance products affect finish? Using the wrong maintenance products may leave a haze or residue, render the floor slick or sticky, temporarily or permanently alter the sheen, prevent the ability to buff-and-recoat, swell the wood via water absorption into the wood and (usually involving conventional wet mops and buckets) cause delamination from the wood or between coats, void a warranty, and other unpleasant consequences. This includes concentrated cleaners not diluted to the proper concentration: one such instance ruined the finish and, given the saturation in the end grain and down the seams, ultimately required complete floor tear-out and replacement. This also includes not following ALL manufacturer guidelines, like not changing out/cleaning mop heads frequently enough. Follow finish manufacturer recommendations for maintenance. If unsure of the finish manufacturer, refer to NWFA guidelines.
For additional information about finishes, check out the NWFA’s technical publications at nwfa.org/technical-guidelines/.