We’ve heard of some similar stories going around… make sure you shake that thing. Forgive us if it sounds patronising, but we all need reminding..!
From Hardwood Flooring Mag…
They applied one coat of penetrating finish stain and two coats of single-component satin water-based polyurethane. The next morning, some areas of the floor appeared almost gloss, while the hall appeared to be matte flat. The master bedroom area looked like semi-gloss.
The contractor and his foreman had left the finishing to one of their newer crews. New to water-base finishes, this crew rolled out two coats of single-component satin water-based polyurethane as told. Being new to using water-based finishes, the idea of thoroughly shaking a finish seemed foreign to them, and almost reckless. Having used an oil-based polyurethane for years, they knew that if you shake that finish, bubbles and foam would prevent a nice, smooth finish application for hours afterwards.
But most modern water-based finishes contain really effective anti-foaming additives that prevent the foaming and bubbling the crew had feared. When the label directions encourage shaking, it is to ensure that all of the contents become equally dispersed prior to pouring the first puddle and line on the floor. This includes the flattening agents, which may settle while in inventory. Gravity isn’t just a good idea, it’s a law.