Q: How long does waterbased polyurethane stay wet on a floor, so that I don’t have the risk of ridges forming?
A: It depends on the temperature and humidity, but even under the best of circumstances, waterbased finish sets up very fast. That means you must work quickly to avoid ridges, and do not go back over the finish once it starts setting up. Basically, warmer, drier conditions mean faster drying. If the finish is a simple evaporative waterbased (some are, some aren’t) you can extend the drying time with Floetrol, but in any case, you will have fewer problems with ridges if you apply several very thin coats instead of only a couple thicker ones. Besides, thinner, smaller ridges are easier to sand out, should you get them.