The drum/belt sander has flattened the floor perfectly, the edges have been expertly blended, and that beautiful planetary sander has caressed the grain to make the floor look like polished glass. It is time for the finish to do its job and get you paid.
Now, the jobsite conditions are perfect, the floor is ready to be sealed/stained and finished and the perfect coats applied. But!
Problems can arise when manufacturers’ recommendations are not followed. Jobsite conditions are very important as temperature, humidity and air flow are all leading contributors to success. Hot spots on the floor from the sun or heating elements, excess air movement from refrigerators or HVAC systems can all cause problems. Clean, uncontaminated applicators and equipment are also vital to the proper application of your finish coats.
Thin to win?
Often, when a contractor calls me with complaints about their coatings, I find that the proper spread rate has not been achieved – sometimes on purpose! “I was taught to lay thin coats – thin to win my old boss used to say!”. With oil-based coatings having a longer open time than water-based coatings, folks would often get away with it. However, if water-based coatings do not get the necessary “open” or “wet edge time” to allow the flow and levelling agents, as well as the defoamers to work, problems can occur. This appears to be a common mistake I hear about.
Manufacturers’ recommendations and the math involved…
At our company, most of our canlak finishes are designed to be applied at the spread rate of 500 square feet per gallon. However, for the sake of easy math, let us talk about Canlak(our 2-part water-based poly) that applies at a 400 square feet per gallon spread rate.
- One coat of canlak applied at 400 square feet per gallon is 4 mils thick when wet.
- Canlak is 50% solids so that same coat has a dry film build of 2 mils (4 x 0.5 = 2)
- In normal conditions that coat has approximately 10-15 minutes of wet edge/open time
- This film has enough time to flow and level out as intended.
Now if we apply a coat at say 600 square feet per gallon the math changes somewhat:
- One coat of Canlak applied at 600 feet per gallon is 2.66 mils wet
- Dry film build is therefore 1.33 mils (2.66 x 0.5 = 1.3 mils)
- In normal conditions this coat has approximately 5-7 minutes of wet edge/open time
This film does not have enough time to flow and level out as intended.
The defoamers and leveling agents did not get the opportunity to do their job as time ran out!
You deserve your floors to look the way you want after all the hard physical work of sanding them, and you deserve to get referrals from past customers who love your work and recommend you to others, and of course, you deserve to get paid and call it a job well done. It is all possible when you follow the manufacturers’ recommended guidelines for application. You worked so hard to sand it well, finish it well so that your customers will be, well, floored…!