Wood Flooring Q&A: Why the Slippery Gym Floor?

Qa 421 Med

After being recoated with poly, our gym floors have a slippery film, and there's a hazy white film collecting on our basketball clear plastic backboards. Why?

Mike Hoy, sales director, Sports Flooring Division, at Jacksonville, Ark.-based PoloPlaz, answers:

Without knowing all the specifics, I can give you the most likely cause: "solvent rain back."

Solvent rain back occurs when a polyurethane is applied while the HVAC system is shut off and not restarted. The HVAC must be put back into operation within two or three hours of the coating being completed. This is done to introduce fresh air back into the space and vent out the solvents. When the system is not restarted, the solvents evaporating off of the coating hang in the air with nowhere to go. Eventually they fall back to the surface of the floor, leaving a film or hazy appearance. If the haze made it as high as your back boards, I must assume two things. First, you have a large floor space (a lot of solvents to linger), and second, the gym must be newer and fairly airtight for efficiency.

If the floor is walkable, tack-clean the floor with a clean towel soaked but not dripping with 100 percent mineral spirits and restore the HVAC to full operation, setting the temp to around 72°F for 48 hours. Make sure the fan is set to run constantly, and allow the heat to engage as needed. Also, if you are in a warmer region, you may need to set heat higher to get it to run.

After 48 hours, reevaluate the floor to see if the film appears to be diminishing. If so, continue for 48 hours and repeat. If there is no improvement, take a clean rag soaked with 100 percent pure mineral spirits and wipe a small area to see if that helps. If it improves, then repeat the tack cleaning and keep the system running for 48 more hours. This should clean up your situation.

If there has been no improvement, this indicates the solvent haze dried into, and became part of, the surface film. The only way to repair this is to repeat the entire screen-and-recoat process. The backboards should wipe right off with normal glass cleaner.

See a video of this problem floor here:


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