Although you may have been installing, sanding, and finishing floors for years, maybe even decades, it’s easy to forget how seasonal changes affect the drying times of finish products. Whether we are water-popping for a deeper color or applying stains, sealers, or finishes, drying conditions will affect the way the products dry. Understanding your conditions will help minimize issues you could have on the job.
First and foremost, always read the directions on the product being used. Even if it is a product you have used for years, double-check the recommended dry times. Manufacturers will not reach out to tell you they have changed their recommendations. Recommended dry times from manufacturers are usually “under ideal conditions,” and most times the jobsite is not ideal.
The No. 1 reason a technical department receives a call is due to a contractor rushing the job; for example, coating over a product before it was dry or allowing a jobsite to return to full service before the flooring system is completely cured. Most of us know the following items can skew the conditions and prolong dry times:
- Too heavy application rates
- Too high humidity levels
- Too low temperature
- Lack of airflow
- Coating a previous coat before it was dry
The National Wood Flooring Association (NWFA) states that flooring should be kept at 60 °F to 80 °F and 30 percent to 50 percent relative humidity. This happens to be similar to conditions in which many finish manufacturers claim their products perform the best. Even though we may be working in conditioned spaces, the weather outside can have an effect on how products dry, especially during the spring and fall when air conditioners/furnaces may not be running as often due to similar temperatures outside.
Those are the times of year in my market where the tech lines light up, and the question is asked, “Did the manufacturer change their product? It’s drying differently.” This is where we have to have the following conversation. In the Midwest, coating floors during these times of the year requires a little more attention to the conditions because HVAC systems do not kick on as often. Thus, in most cases, the indoor conditions will inherently see an increase in the humidity levels (a closed-up home with no air movement may increase in humidity). In addition, this is usually the time of year where the humidity levels rise and our dew-point becomes much closer to our temperatures.
This is why it is a good idea to have a thermo-hygrometer and to check the temperature and humidity as you start coating. This will give you an idea of how your products will dry that day, in that home. After a period of tracking this information, you will become very familiar with how your products will perform in the varying conditions.
In addition to the above-mentioned HVAC items, the amount of flooring in a home being coated can skew the dry times. This happens to be one of the most overlooked pieces of information when calculating drying conditions. For instance, a 200-square-foot floor being sanded and finished in a 2,000-square-foot home will have better drying conditions than an 1,800-square-foot floor in the same home.
With a larger amount of flooring being worked on, the amount of moisture/solvent being added to the home is greater, thus loading the air. This moisture/solvent that is being released from the finish system is heavier than the air and will sit at floor level, pretty much stopping the drying process, making it more important to exhaust the air, either by adding airflow or, even better, putting fans in the windows blowing out. This usually can be done without issue after the products have skinned over. And yes, this may require the finishing crew to hang around or return to the job to add this airflow once the products have flashed off. But what is worse, taking the time to make this happen or having to recoat/resand the project due to a finish issue?
Monitoring and understanding the changing drying conditions as the seasons change can prevent you from having to adjust your already-tight schedule to squeeze in another finish coat or a resand.
Matt Thrane is Training/Sales Manager at Gehl Flooring Supply Inc. in Wauwatosa, Wisconsin. He can be reached at firstname.lastname@example.org.